Skip to content

DataFrame#

Most DataFrame methods are lazy, meaning that they do not execute computation immediately when invoked. Instead, these operations are enqueued in the DataFrame's internal query plan, and are only executed when Execution DataFrame methods are called. Learn more about DataFrames in Daft User Guide.

DataFrame #

DataFrame(builder: LogicalPlanBuilder)

A Daft DataFrame is a table of data.

It has columns, where each column has a type and the same number of items (rows) as all other columns.

Constructs a DataFrame according to a given LogicalPlan.

Users are expected instead to call the classmethods on DataFrame to create a DataFrame.

Parameters:

Name Type Description Default
plan

LogicalPlan describing the steps required to arrive at this DataFrame

required

Methods:

Name Description
__contains__

Returns whether the column exists in the dataframe.

__getitem__

Gets a column from the DataFrame as an Expression (df["mycol"]).

__iter__

Alias of self.iter_rows() with default arguments for convenient access of data.

__len__

Returns the count of rows when dataframe is materialized.

agg

Perform aggregations on this DataFrame.

agg_concat

Performs a global list concatenation agg on the DataFrame.

agg_list

Performs a global list agg on the DataFrame.

agg_set

Performs a global set agg on the DataFrame (ignoring nulls).

any_value

Returns an arbitrary value on this DataFrame.

collect

Executes the entire DataFrame and materializes the results.

concat

Concatenates two DataFrames together in a "vertical" concatenation.

count

Performs a global count on the DataFrame.

count_rows

Executes the Dataframe to count the number of rows.

describe

Returns the Schema of the DataFrame, which provides information about each column, as a new DataFrame.

distinct

Computes distinct rows, dropping duplicates.

drop_nan

Drops rows that contains NaNs. If cols is None it will drop rows with any NaN value.

drop_null

Drops rows that contains NaNs or NULLs. If cols is None it will drop rows with any NULL value.

except_all

Returns the set difference of two DataFrames, considering duplicates.

except_distinct

Returns the set difference of two DataFrames.

exclude

Drops columns from the current DataFrame by name.

explain

Prints the (logical and physical) plans that will be executed to produce this DataFrame.

explode

Explodes a List column, where every element in each row's List becomes its own row, and all other columns in the DataFrame are duplicated across rows.

filter

Filters rows via a predicate expression, similar to SQL WHERE.

groupby

Performs a GroupBy on the DataFrame for aggregation.

intersect

Returns the intersection of two DataFrames.

intersect_all

Returns the intersection of two DataFrames, including duplicates.

into_partitions

Splits or coalesces DataFrame to num partitions. Order is preserved.

iter_partitions

Begin executing this dataframe and return an iterator over the partitions.

iter_rows

Return an iterator of rows for this dataframe.

join

Column-wise join of the current DataFrame with an other DataFrame, similar to a SQL JOIN.

limit

Limits the rows in the DataFrame to the first N rows, similar to a SQL LIMIT.

max

Performs a global max on the DataFrame.

mean

Performs a global mean on the DataFrame.

melt

Alias for unpivot.

min

Performs a global min on the DataFrame.

num_partitions
pipe

Apply the function to this DataFrame.

pivot

Pivots a column of the DataFrame and performs an aggregation on the values.

repartition

Repartitions DataFrame to num partitions.

sample

Samples a fraction of rows from the DataFrame.

schema

Returns the Schema of the DataFrame, which provides information about each column, as a Python object.

select

Creates a new DataFrame from the provided expressions, similar to a SQL SELECT.

show

Executes enough of the DataFrame in order to display the first n rows.

sort

Sorts DataFrame globally.

stddev

Performs a global standard deviation on the DataFrame.

sum

Performs a global sum on the DataFrame.

summarize

Returns column statistics for the DataFrame.

to_arrow

Converts the current DataFrame to a pyarrow Table.

to_arrow_iter

Return an iterator of pyarrow recordbatches for this dataframe.

to_dask_dataframe

Converts the current Daft DataFrame to a Dask DataFrame.

to_pandas

Converts the current DataFrame to a pandas DataFrame.

to_pydict

Converts the current DataFrame to a python dictionary. The dictionary contains Python lists of Python objects for each column.

to_pylist

Converts the current Dataframe into a python list.

to_ray_dataset

Converts the current DataFrame to a Ray Dataset which is useful for running distributed ML model training in Ray.

to_torch_iter_dataset

Convert the current DataFrame into a Torch IterableDataset <https://pytorch.org/docs/stable/data.html#torch.utils.data.IterableDataset>__ for use with PyTorch.

to_torch_map_dataset

Convert the current DataFrame into a map-style Torch Dataset for use with PyTorch.

transform

Apply a function that takes and returns a DataFrame.

union

Returns the distinct union of two DataFrames.

union_all

Returns the union of two DataFrames, including duplicates.

union_all_by_name

Returns the union of two DataFrames, including duplicates, with columns matched by name.

union_by_name

Returns the distinct union by name.

unique

Computes distinct rows, dropping duplicates.

unpivot

Unpivots a DataFrame from wide to long format.

where

Filters rows via a predicate expression, similar to SQL WHERE.

with_column

Adds a column to the current DataFrame with an Expression, equivalent to a select with all current columns and the new one.

with_column_renamed

Renames a column in the current DataFrame.

with_columns

Adds columns to the current DataFrame with Expressions, equivalent to a select with all current columns and the new ones.

with_columns_renamed

Renames multiple columns in the current DataFrame.

write_csv

Writes the DataFrame as CSV files, returning a new DataFrame with paths to the files that were written.

write_deltalake

Writes the DataFrame to a Delta Lake table, returning a new DataFrame with the operations that occurred.

write_iceberg

Writes the DataFrame to an Iceberg table, returning a new DataFrame with the operations that occurred.

write_lance

Writes the DataFrame to a Lance table.

write_parquet

Writes the DataFrame as parquet files, returning a new DataFrame with paths to the files that were written.

write_sink

Writes the DataFrame to the given DataSink.

Attributes:

Name Type Description
column_names List[str]

Returns column names of DataFrame as a list of strings.

columns List[Expression]

Returns column of DataFrame as a list of Expressions.

Source code in daft/dataframe/dataframe.py
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
def __init__(self, builder: LogicalPlanBuilder) -> None:
    """Constructs a DataFrame according to a given LogicalPlan.

    Users are expected instead to call the classmethods on DataFrame to create a DataFrame.

    Args:
        plan: LogicalPlan describing the steps required to arrive at this DataFrame
    """
    if not isinstance(builder, LogicalPlanBuilder):
        if isinstance(builder, dict):
            raise ValueError(
                "DataFrames should be constructed with a dictionary of columns using `daft.from_pydict`"
            )
        if isinstance(builder, list):
            raise ValueError(
                "DataFrames should be constructed with a list of dictionaries using `daft.from_pylist`"
            )
        raise ValueError(f"Expected DataFrame to be constructed with a LogicalPlanBuilder, received: {builder}")

    self.__builder = builder
    self._result_cache: Optional[PartitionCacheEntry] = None
    self._preview = Preview(partition=None, total_rows=None)
    self._num_preview_rows = get_context().daft_execution_config.num_preview_rows

column_names #

column_names: List[str]

Returns column names of DataFrame as a list of strings.

Returns:

Type Description
List[str]

List[str]: Column names of this DataFrame.

columns #

columns: List[Expression]

Returns column of DataFrame as a list of Expressions.

Returns:

Type Description
List[Expression]

List[Expression]: Columns of this DataFrame.

__contains__ #

__contains__(col_name: str) -> bool

Returns whether the column exists in the dataframe.

Parameters:

Name Type Description Default
col_name str

column name

required

Returns:

Name Type Description
bool bool

whether the column exists in the dataframe.

Examples:

1
2
3
4
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> "x" in df
True
Source code in daft/dataframe/dataframe.py
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
def __contains__(self, col_name: str) -> bool:
    """Returns whether the column exists in the dataframe.

    Args:
        col_name (str): column name

    Returns:
        bool: whether the column exists in the dataframe.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> "x" in df
        True

    """
    return col_name in self.column_names

__getitem__ #

__getitem__(
    item: Union[slice, int, str, Iterable[Union[str, int]]],
) -> Union[Expression, DataFrame]

Gets a column from the DataFrame as an Expression (df["mycol"]).

Source code in daft/dataframe/dataframe.py
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
def __getitem__(self, item: Union[slice, int, str, Iterable[Union[str, int]]]) -> Union[Expression, "DataFrame"]:
    """Gets a column from the DataFrame as an Expression (``df["mycol"]``)."""
    result: Optional[Expression]

    if isinstance(item, int):
        schema = self._builder.schema()
        if item < -len(schema) or item >= len(schema):
            raise ValueError(f"{item} out of bounds for {schema}")
        result = ExpressionsProjection.from_schema(schema)[item]
        assert result is not None
        return result
    elif isinstance(item, str):
        schema = self._builder.schema()
        if item not in schema.column_names() and item != "*":
            raise ValueError(f"{item} does not exist in schema {schema}")

        return col(item)
    elif isinstance(item, Iterable):
        schema = self._builder.schema()

        columns = []
        for it in item:
            if isinstance(it, str):
                result = col(schema[it].name)
                columns.append(result)
            elif isinstance(it, int):
                if it < -len(schema) or it >= len(schema):
                    raise ValueError(f"{it} out of bounds for {schema}")
                field = list(self._builder.schema())[it]
                columns.append(col(field.name))
            else:
                raise ValueError(f"unknown indexing type: {type(it)}")
        return self.select(*columns)
    elif isinstance(item, slice):
        schema = self._builder.schema()
        columns_exprs: ExpressionsProjection = ExpressionsProjection.from_schema(schema)
        selected_columns = columns_exprs[item]
        return self.select(*selected_columns)
    else:
        raise ValueError(f"unknown indexing type: {type(item)}")

__iter__ #

__iter__() -> Iterator[Dict[str, Any]]

Alias of self.iter_rows() with default arguments for convenient access of data.

Source code in daft/dataframe/dataframe.py
329
330
331
332
@DataframePublicAPI
def __iter__(self) -> Iterator[Dict[str, Any]]:
    """Alias of `self.iter_rows()` with default arguments for convenient access of data."""
    return self.iter_rows(results_buffer_size=None)

__len__ #

__len__()

Returns the count of rows when dataframe is materialized.

If dataframe is not materialized yet, raises a runtime error.

Returns:

Name Type Description
int

count of rows.

Source code in daft/dataframe/dataframe.py
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
def __len__(self):
    """Returns the count of rows when dataframe is materialized.

    If dataframe is not materialized yet, raises a runtime error.

    Returns:
        int: count of rows.

    """
    if self._result is not None:
        return len(self._result)

    message = (
        "Cannot call len() on an unmaterialized dataframe:"
        " either materialize your dataframe with df.collect() first before calling len(),"
        " or use `df.count_rows()` instead which will calculate the total number of rows."
    )
    raise RuntimeError(message)

agg #

agg(
    *to_agg: Union[Expression, Iterable[Expression]],
) -> DataFrame

Perform aggregations on this DataFrame.

Allows for mixed aggregations for multiple columns and will return a single row that aggregated the entire DataFrame.

Parameters:

Name Type Description Default
*to_agg Expression

aggregation expressions

()

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with aggregated results

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
>>> import daft
>>> from daft import col
>>> df = daft.from_pydict(
...     {"student_id": [1, 2, 3, 4], "test1": [0.5, 0.4, 0.6, 0.7], "test2": [0.9, 0.8, 0.7, 1.0]}
... )
>>> agg_df = df.agg(
...     col("test1").mean(),
...     col("test2").mean(),
...     ((col("test1") + col("test2")) / 2).min().alias("total_min"),
...     ((col("test1") + col("test2")) / 2).max().alias("total_max"),
... )
>>> agg_df.show()
╭─────────┬────────────────────┬────────────────────┬───────────╮
│ test1   ┆ test2              ┆ total_min          ┆ total_max │
│ ---     ┆ ---                ┆ ---                ┆ ---       │
│ Float64 ┆ Float64            ┆ Float64            ┆ Float64   │
╞═════════╪════════════════════╪════════════════════╪═══════════╡
│ 0.55    ┆ 0.8500000000000001 ┆ 0.6000000000000001 ┆ 0.85      │
╰─────────┴────────────────────┴────────────────────┴───────────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
@DataframePublicAPI
def agg(self, *to_agg: Union[Expression, Iterable[Expression]]) -> "DataFrame":
    """Perform aggregations on this DataFrame.

    Allows for mixed aggregations for multiple columns and will return a single row that aggregated the entire DataFrame.

    Args:
        *to_agg (Expression): aggregation expressions

    Returns:
        DataFrame: DataFrame with aggregated results

    Examples:
        >>> import daft
        >>> from daft import col
        >>> df = daft.from_pydict(
        ...     {"student_id": [1, 2, 3, 4], "test1": [0.5, 0.4, 0.6, 0.7], "test2": [0.9, 0.8, 0.7, 1.0]}
        ... )
        >>> agg_df = df.agg(
        ...     col("test1").mean(),
        ...     col("test2").mean(),
        ...     ((col("test1") + col("test2")) / 2).min().alias("total_min"),
        ...     ((col("test1") + col("test2")) / 2).max().alias("total_max"),
        ... )
        >>> agg_df.show()
        ╭─────────┬────────────────────┬────────────────────┬───────────╮
        │ test1   ┆ test2              ┆ total_min          ┆ total_max │
        │ ---     ┆ ---                ┆ ---                ┆ ---       │
        │ Float64 ┆ Float64            ┆ Float64            ┆ Float64   │
        ╞═════════╪════════════════════╪════════════════════╪═══════════╡
        │ 0.55    ┆ 0.8500000000000001 ┆ 0.6000000000000001 ┆ 0.85      │
        ╰─────────┴────────────────────┴────────────────────┴───────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

    """
    to_agg_list = (
        list(to_agg[0])
        if (len(to_agg) == 1 and not isinstance(to_agg[0], Expression))
        else list(typing.cast("Tuple[Expression]", to_agg))
    )

    for expr in to_agg_list:
        if not isinstance(expr, Expression):
            raise ValueError(f"DataFrame.agg() only accepts expression type, received: {type(expr)}")

    return self._agg(to_agg_list, group_by=None)

agg_concat #

agg_concat(*cols: ColumnInputType) -> DataFrame

Performs a global list concatenation agg on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns that are lists to concatenate

()

Returns: DataFrame: Globally aggregated list. Should be a single row.

Source code in daft/dataframe/dataframe.py
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
@DataframePublicAPI
def agg_concat(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global list concatenation agg on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns that are lists to concatenate
    Returns:
        DataFrame: Globally aggregated list. Should be a single row.
    """
    return self._apply_agg_fn(Expression.agg_concat, cols)

agg_list #

agg_list(*cols: ColumnInputType) -> DataFrame

Performs a global list agg on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to form into a list

()

Returns: DataFrame: Globally aggregated list. Should be a single row.

Source code in daft/dataframe/dataframe.py
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
@DataframePublicAPI
def agg_list(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global list agg on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to form into a list
    Returns:
        DataFrame: Globally aggregated list. Should be a single row.
    """
    return self._apply_agg_fn(Expression.agg_list, cols)

agg_set #

agg_set(*cols: ColumnInputType) -> DataFrame

Performs a global set agg on the DataFrame (ignoring nulls).

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to form into a set

()

Returns:

Name Type Description
DataFrame DataFrame

Globally aggregated set. Should be a single row.

Source code in daft/dataframe/dataframe.py
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
@DataframePublicAPI
def agg_set(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global set agg on the DataFrame (ignoring nulls).

    Args:
        *cols (Union[str, Expression]): columns to form into a set

    Returns:
        DataFrame: Globally aggregated set. Should be a single row.
    """
    return self._apply_agg_fn(Expression.agg_set, cols)

any_value #

any_value(*cols: ColumnInputType) -> DataFrame

Returns an arbitrary value on this DataFrame.

Values for each column are not guaranteed to be from the same row.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to get an arbitrary value from

()

Returns: DataFrame: DataFrame with any values.

Source code in daft/dataframe/dataframe.py
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
@DataframePublicAPI
def any_value(self, *cols: ColumnInputType) -> "DataFrame":
    """Returns an arbitrary value on this DataFrame.

    Values for each column are not guaranteed to be from the same row.

    Args:
        *cols (Union[str, Expression]): columns to get an arbitrary value from
    Returns:
        DataFrame: DataFrame with any values.
    """
    return self._apply_agg_fn(Expression.any_value, cols)

collect #

collect(num_preview_rows: Optional[int] = 8) -> DataFrame

Executes the entire DataFrame and materializes the results.

Parameters:

Name Type Description Default
num_preview_rows Optional[int]

Number of rows to preview. Defaults to 8.

8

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with materialized results.

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
@DataframePublicAPI
def collect(self, num_preview_rows: Optional[int] = 8) -> "DataFrame":
    """Executes the entire DataFrame and materializes the results.

    Args:
        num_preview_rows: Number of rows to preview. Defaults to 8.

    Returns:
        DataFrame: DataFrame with materialized results.

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    plan_time_start = _utc_now()
    self._materialize_results()
    plan_time_end = _utc_now()
    self._broadcast_query_plan(plan_time_start, plan_time_end)
    assert self._result is not None
    dataframe_len = len(self._result)
    if num_preview_rows is not None:
        self._num_preview_rows = num_preview_rows
    else:
        self._num_preview_rows = dataframe_len
    return self

concat #

concat(other: DataFrame) -> DataFrame

Concatenates two DataFrames together in a "vertical" concatenation.

The resulting DataFrame has number of rows equal to the sum of the number of rows of the input DataFrames.

Parameters:

Name Type Description Default
other DataFrame

other DataFrame to concatenate

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with rows from self on top and rows from other at the bottom.

Note

DataFrames being concatenated must have exactly the same schema. You may wish to use the df.select() and expr.cast() methods to ensure schema compatibility before concatenation.

Source code in daft/dataframe/dataframe.py
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
@DataframePublicAPI
def concat(self, other: "DataFrame") -> "DataFrame":
    """Concatenates two DataFrames together in a "vertical" concatenation.

    The resulting DataFrame has number of rows equal to the sum of the number of rows of the input DataFrames.

    Args:
        other (DataFrame): other DataFrame to concatenate

    Returns:
        DataFrame: DataFrame with rows from `self` on top and rows from `other` at the bottom.

    Note:
        DataFrames being concatenated **must have exactly the same schema**. You may wish to use the
        [df.select()][daft.DataFrame.select] and [expr.cast()][daft.expressions.Expression.cast] methods
        to ensure schema compatibility before concatenation.
    """
    if self.schema() != other.schema():
        raise ValueError(
            f"DataFrames must have exactly the same schema for concatenation!\nExpected:\n{self.schema()}\n\nReceived:\n{other.schema()}"
        )
    builder = self._builder.concat(other._builder)
    return DataFrame(builder)

count #

count(*cols: ColumnInputType) -> DataFrame

Performs a global count on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to count

()

Returns: DataFrame: Globally aggregated count. Should be a single row.

Examples:

If no columns are specified (i.e. in the case you call df.count()), or only the literal string "", this functions very similarly to a COUNT() operation in SQL and will return a new dataframe with a single column with the name "count".

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
>>> import daft
>>> from daft import col
>>> df = daft.from_pydict({"foo": [1, None, None], "bar": [None, 2, 2], "baz": [3, 4, 5]})
>>> df.count().show()  # equivalent to df.count("*").show()
╭────────╮
│ count  │
│ ---    │
│ UInt64 │
╞════════╡
│ 3      │
╰────────╯

(Showing first 1 of 1 rows)

However, specifying some column names would instead change the behavior to count all non-null values, similar to a SQL command for SELECT COUNT(foo), COUNT(bar) FROM df. Also, using df.count(col("*")) will expand out into count() for each column.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
>>> df.count("foo", "bar").show()
╭────────┬────────╮
│ foo    ┆ bar    │
│ ---    ┆ ---    │
│ UInt64 ┆ UInt64 │
╞════════╪════════╡
│ 1      ┆ 2      │
╰────────┴────────╯

(Showing first 1 of 1 rows)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
>>> df.count(col("*")).show()
╭────────┬────────┬────────╮
│ foo    ┆ bar    ┆ baz    │
│ ---    ┆ ---    ┆ ---    │
│ UInt64 ┆ UInt64 ┆ UInt64 │
╞════════╪════════╪════════╡
│ 1      ┆ 2      ┆ 3      │
╰────────┴────────┴────────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
@DataframePublicAPI
def count(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global count on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to count
    Returns:
        DataFrame: Globally aggregated count. Should be a single row.

    Examples:
        If no columns are specified (i.e. in the case you call `df.count()`), or only the literal string "*",
        this functions very similarly to a COUNT(*) operation in SQL and will return a new dataframe with a
        single column with the name "count".

        >>> import daft
        >>> from daft import col
        >>> df = daft.from_pydict({"foo": [1, None, None], "bar": [None, 2, 2], "baz": [3, 4, 5]})
        >>> df.count().show()  # equivalent to df.count("*").show()
        ╭────────╮
        │ count  │
        │ ---    │
        │ UInt64 │
        ╞════════╡
        │ 3      │
        ╰────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

        However, specifying some column names would instead change the behavior to count all non-null values,
        similar to a SQL command for `SELECT COUNT(foo), COUNT(bar) FROM df`. Also, using `df.count(col("*"))`
        will expand out into count() for each column.

        >>> df.count("foo", "bar").show()
        ╭────────┬────────╮
        │ foo    ┆ bar    │
        │ ---    ┆ ---    │
        │ UInt64 ┆ UInt64 │
        ╞════════╪════════╡
        │ 1      ┆ 2      │
        ╰────────┴────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

        >>> df.count(col("*")).show()
        ╭────────┬────────┬────────╮
        │ foo    ┆ bar    ┆ baz    │
        │ ---    ┆ ---    ┆ ---    │
        │ UInt64 ┆ UInt64 ┆ UInt64 │
        ╞════════╪════════╪════════╡
        │ 1      ┆ 2      ┆ 3      │
        ╰────────┴────────┴────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

    """
    # Special case: treat this as a COUNT(*) operation which is likely what most people would expect
    # If user passes in "*", also do this behavior (by default it would count each column individually)
    if len(cols) == 0 or (len(cols) == 1 and isinstance(cols[0], str) and cols[0] == "*"):
        builder = self._builder.count()
        return DataFrame(builder)

    if any(isinstance(c, str) and c == "*" for c in cols):
        # we do not support hybrid count-all and count-nonnull
        raise ValueError("Cannot call count() with both * and column names")

    # Otherwise, perform a column-wise count on the specified columns
    return self._apply_agg_fn(Expression.count, cols)

count_rows #

count_rows() -> int

Executes the Dataframe to count the number of rows.

Returns:

Name Type Description
int int

count of the number of rows in this DataFrame.

Source code in daft/dataframe/dataframe.py
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
@DataframePublicAPI
def count_rows(self) -> int:
    """Executes the Dataframe to count the number of rows.

    Returns:
        int: count of the number of rows in this DataFrame.
    """
    builder = self._builder.count()
    count_df = DataFrame(builder)
    # Expects builder to produce a single-partition, single-row DataFrame containing
    # a "count" column, where the lone value represents the row count for the DataFrame.
    return count_df.to_pydict()["count"][0]

describe #

describe() -> DataFrame

Returns the Schema of the DataFrame, which provides information about each column, as a new DataFrame.

Returns:

Name Type Description
DataFrame DataFrame

A dataframe where each row is a column name and its corresponding type.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
>>> import daft
>>> df = daft.from_pydict({"a": [1, 2, 3], "b": ["x", "y", "z"]})
>>> df.describe().show()
╭─────────────┬───────╮
│ column_name ┆ type  │
│ ---         ┆ ---   │
│ Utf8        ┆ Utf8  │
╞═════════════╪═══════╡
│ a           ┆ Int64 │
├╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ b           ┆ Utf8  │
╰─────────────┴───────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
@DataframePublicAPI
def describe(self) -> "DataFrame":
    """Returns the Schema of the DataFrame, which provides information about each column, as a new DataFrame.

    Returns:
        DataFrame: A dataframe where each row is a column name and its corresponding type.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"a": [1, 2, 3], "b": ["x", "y", "z"]})
        >>> df.describe().show()
        ╭─────────────┬───────╮
        │ column_name ┆ type  │
        │ ---         ┆ ---   │
        │ Utf8        ┆ Utf8  │
        ╞═════════════╪═══════╡
        │ a           ┆ Int64 │
        ├╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ b           ┆ Utf8  │
        ╰─────────────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)
    """
    builder = self.__builder.describe()
    return DataFrame(builder)

distinct #

distinct() -> DataFrame

Computes distinct rows, dropping duplicates.

Returns:

Name Type Description
DataFrame DataFrame

DataFrame that has only distinct rows.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 2], "y": [4, 5, 5], "z": [7, 8, 8]})
>>> distinct_df = df.distinct()
>>> distinct_df = distinct_df.sort("x")
>>> distinct_df.show()
╭───────┬───────┬───────╮
│ x     ┆ y     ┆ z     │
│ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1     ┆ 4     ┆ 7     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 8     │
╰───────┴───────┴───────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
@DataframePublicAPI
def distinct(self) -> "DataFrame":
    """Computes distinct rows, dropping duplicates.

    Returns:
        DataFrame: DataFrame that has only distinct rows.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 2], "y": [4, 5, 5], "z": [7, 8, 8]})
        >>> distinct_df = df.distinct()
        >>> distinct_df = distinct_df.sort("x")
        >>> distinct_df.show()
        ╭───────┬───────┬───────╮
        │ x     ┆ y     ┆ z     │
        │ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╡
        │ 1     ┆ 4     ┆ 7     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 8     │
        ╰───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)
    """
    ExpressionsProjection.from_schema(self._builder.schema())
    builder = self._builder.distinct()
    return DataFrame(builder)

drop_nan #

drop_nan(*cols: ColumnInputType)

Drops rows that contains NaNs. If cols is None it will drop rows with any NaN value.

If column names are supplied, it will drop only those rows that contains NaNs in one of these columns.

Parameters:

Name Type Description Default
*cols str

column names by which rows containing nans/NULLs should be filtered

()

Returns:

Name Type Description
DataFrame

DataFrame without NaNs in specified/all columns

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"a": [1.0, 2.2, 3.5, float("nan")]})
>>> df.drop_nan().collect()  # drops rows where any column contains NaN values
╭─────────╮
│ a       │
│ ---     │
│ Float64 │
╞═════════╡
│ 1       │
├╌╌╌╌╌╌╌╌╌┤
│ 2.2     │
├╌╌╌╌╌╌╌╌╌┤
│ 3.5     │
╰─────────╯

(Showing first 3 of 3 rows)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"a": [1.6, 2.5, 3.3, float("nan")]})
>>> df.drop_nan("a").collect()  # drops rows where column `a` contains NaN values
╭─────────╮
│ a       │
│ ---     │
│ Float64 │
╞═════════╡
│ 1.6     │
├╌╌╌╌╌╌╌╌╌┤
│ 2.5     │
├╌╌╌╌╌╌╌╌╌┤
│ 3.3     │
╰─────────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
@DataframePublicAPI
def drop_nan(self, *cols: ColumnInputType):
    """Drops rows that contains NaNs. If cols is None it will drop rows with any NaN value.

    If column names are supplied, it will drop only those rows that contains NaNs in one of these columns.

    Args:
        *cols (str): column names by which rows containing nans/NULLs should be filtered

    Returns:
        DataFrame: DataFrame without NaNs in specified/all columns

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"a": [1.0, 2.2, 3.5, float("nan")]})
        >>> df.drop_nan().collect()  # drops rows where any column contains NaN values
        ╭─────────╮
        │ a       │
        │ ---     │
        │ Float64 │
        ╞═════════╡
        │ 1       │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 2.2     │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 3.5     │
        ╰─────────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

        >>> import daft
        >>> df = daft.from_pydict({"a": [1.6, 2.5, 3.3, float("nan")]})
        >>> df.drop_nan("a").collect()  # drops rows where column `a` contains NaN values
        ╭─────────╮
        │ a       │
        │ ---     │
        │ Float64 │
        ╞═════════╡
        │ 1.6     │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 2.5     │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 3.3     │
        ╰─────────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

    """
    if len(cols) == 0:
        columns = self.__column_input_to_expression(self.column_names)
    else:
        columns = self.__column_input_to_expression(cols)
    float_columns = [
        column
        for column in columns
        if (
            column._to_field(self.schema()).dtype == DataType.float32()
            or column._to_field(self.schema()).dtype == DataType.float64()
        )
    ]

    # avoid superfluous .where with empty iterable when nothing to filter.
    if not float_columns:
        return self

    return self.where(
        ~reduce(
            lambda x, y: x.is_null().if_else(lit(False), x) | y.is_null().if_else(lit(False), y),
            (x.float.is_nan() for x in float_columns),
        )
    )

drop_null #

drop_null(*cols: ColumnInputType)

Drops rows that contains NaNs or NULLs. If cols is None it will drop rows with any NULL value.

If column names are supplied, it will drop only those rows that contains NULLs in one of these columns.

Parameters:

Name Type Description Default
*cols str

column names by which rows containing nans should be filtered

()

Returns:

Name Type Description
DataFrame

DataFrame without missing values in specified/all columns

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"a": [1.6, 2.5, None, float("NaN")]})
>>> df.drop_null("a").collect()
╭─────────╮
│ a       │
│ ---     │
│ Float64 │
╞═════════╡
│ 1.6     │
├╌╌╌╌╌╌╌╌╌┤
│ 2.5     │
├╌╌╌╌╌╌╌╌╌┤
│ NaN     │
╰─────────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
@DataframePublicAPI
def drop_null(self, *cols: ColumnInputType):
    """Drops rows that contains NaNs or NULLs. If cols is None it will drop rows with any NULL value.

    If column names are supplied, it will drop only those rows that contains NULLs in one of these columns.

    Args:
        *cols (str): column names by which rows containing nans should be filtered

    Returns:
        DataFrame: DataFrame without missing values in specified/all columns

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"a": [1.6, 2.5, None, float("NaN")]})
        >>> df.drop_null("a").collect()
        ╭─────────╮
        │ a       │
        │ ---     │
        │ Float64 │
        ╞═════════╡
        │ 1.6     │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 2.5     │
        ├╌╌╌╌╌╌╌╌╌┤
        │ NaN     │
        ╰─────────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)


    """
    if len(cols) == 0:
        columns = self.__column_input_to_expression(self.column_names)
    else:
        columns = self.__column_input_to_expression(cols)
    return self.where(~reduce(lambda x, y: x | y, (x.is_null() for x in columns)))

except_all #

except_all(other: DataFrame) -> DataFrame

Returns the set difference of two DataFrames, considering duplicates.

Parameters:

Name Type Description Default
other DataFrame

DataFrame to except with

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the set difference of the two DataFrames, considering duplicates

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
>>> import daft
>>> df1 = daft.from_pydict({"a": [1, 1, 2, 2], "b": [4, 4, 6, 6]})
>>> df2 = daft.from_pydict({"a": [1, 2, 2], "b": [4, 6, 6]})
>>> df1.except_all(df2).collect()
╭───────┬───────╮
│ a     ┆ b     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
╰───────┴───────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
@DataframePublicAPI
def except_all(self, other: "DataFrame") -> "DataFrame":
    """Returns the set difference of two DataFrames, considering duplicates.

    Args:
        other (DataFrame): DataFrame to except with

    Returns:
        DataFrame: DataFrame with the set difference of the two DataFrames, considering duplicates

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"a": [1, 1, 2, 2], "b": [4, 4, 6, 6]})
        >>> df2 = daft.from_pydict({"a": [1, 2, 2], "b": [4, 6, 6]})
        >>> df1.except_all(df2).collect()
        ╭───────┬───────╮
        │ a     ┆ b     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

    """
    builder = self._builder.except_all(other._builder)
    return DataFrame(builder)

except_distinct #

except_distinct(other: DataFrame) -> DataFrame

Returns the set difference of two DataFrames.

Parameters:

Name Type Description Default
other DataFrame

DataFrame to except with

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the set difference of the two DataFrames

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
>>> import daft
>>> df1 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 5, 6]})
>>> df2 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 8, 6]})
>>> df1.except_distinct(df2).collect()
╭───────┬───────╮
│ a     ┆ b     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2     ┆ 5     │
╰───────┴───────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
@DataframePublicAPI
def except_distinct(self, other: "DataFrame") -> "DataFrame":
    """Returns the set difference of two DataFrames.

    Args:
        other (DataFrame): DataFrame to except with

    Returns:
        DataFrame: DataFrame with the set difference of the two DataFrames

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 5, 6]})
        >>> df2 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 8, 6]})
        >>> df1.except_distinct(df2).collect()
        ╭───────┬───────╮
        │ a     ┆ b     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 2     ┆ 5     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

    """
    builder = self._builder.except_distinct(other._builder)
    return DataFrame(builder)

exclude #

exclude(*names: str) -> DataFrame

Drops columns from the current DataFrame by name.

This is equivalent of performing a select with all the columns but the ones excluded.

Parameters:

Name Type Description Default
*names str

names to exclude

()

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with some columns excluded.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> df_without_x = df.exclude("x")
>>> df_without_x.show()
╭───────┬───────╮
│ y     ┆ z     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 4     ┆ 7     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 5     ┆ 8     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 6     ┆ 9     │
╰───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
@DataframePublicAPI
def exclude(self, *names: str) -> "DataFrame":
    """Drops columns from the current DataFrame by name.

    This is equivalent of performing a select with all the columns but the ones excluded.

    Args:
        *names (str): names to exclude

    Returns:
        DataFrame: DataFrame with some columns excluded.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> df_without_x = df.exclude("x")
        >>> df_without_x.show()
        ╭───────┬───────╮
        │ y     ┆ z     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 4     ┆ 7     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 5     ┆ 8     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 6     ┆ 9     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    builder = self._builder.exclude(list(names))
    return DataFrame(builder)

explain #

explain(
    show_all: bool = False,
    format: str = "ascii",
    simple: bool = False,
    file: Optional[IOBase] = None,
) -> Any

Prints the (logical and physical) plans that will be executed to produce this DataFrame.

Defaults to showing the unoptimized logical plan. Use show_all=True to show the unoptimized logical plan, the optimized logical plan, and the physical plan.

Parameters:

Name Type Description Default
show_all bool

Whether to show the optimized logical plan and the physical plan in addition to the unoptimized logical plan.

False
format str

The format to print the plan in. one of 'ascii' or 'mermaid'

'ascii'
simple bool

Whether to only show the type of op for each node in the plan, rather than showing details of how each op is configured.

False
file Optional[IOBase]

Location to print the output to, or defaults to None which defaults to the default location for print (in Python, that should be sys.stdout)

None
Source code in daft/dataframe/dataframe.py
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
@DataframePublicAPI
def explain(
    self, show_all: bool = False, format: str = "ascii", simple: bool = False, file: Optional[io.IOBase] = None
) -> Any:
    """Prints the (logical and physical) plans that will be executed to produce this DataFrame.

    Defaults to showing the unoptimized logical plan. Use `show_all=True` to show the unoptimized logical plan,
    the optimized logical plan, and the physical plan.

    Args:
        show_all (bool): Whether to show the optimized logical plan and the physical plan in addition to the
            unoptimized logical plan.
        format (str): The format to print the plan in. one of 'ascii' or 'mermaid'
        simple (bool): Whether to only show the type of op for each node in the plan, rather than showing details
            of how each op is configured.

        file (Optional[io.IOBase]): Location to print the output to, or defaults to None which defaults to the default location for
            print (in Python, that should be sys.stdout)
    """
    is_cached = self._result_cache is not None
    if format == "mermaid":
        from daft.dataframe.display import MermaidFormatter
        from daft.utils import in_notebook

        instance = MermaidFormatter(self.__builder, show_all, simple, is_cached)
        if file is not None:
            # if we are printing to a file, we print the markdown representation of the plan
            text = instance._repr_markdown_()
            print(text, file=file)
        if in_notebook():
            # if in a notebook, we return the class instance and let jupyter display it
            return instance
        else:
            # if we are not in a notebook, we return the raw markdown instead of the class instance
            return repr(instance)

    print_to_file = partial(print, file=file)

    if self._result_cache is not None:
        print_to_file("Result is cached and will skip computation\n")
        print_to_file(self._builder.pretty_print(simple, format=format))

        print_to_file("However here is the logical plan used to produce this result:\n", file=file)

    builder = self.__builder
    print_to_file("== Unoptimized Logical Plan ==\n")
    print_to_file(builder.pretty_print(simple, format=format))
    if show_all:
        print_to_file("\n== Optimized Logical Plan ==\n")
        builder = builder.optimize()
        print_to_file(builder.pretty_print(simple))
        print_to_file("\n== Physical Plan ==\n")
        if get_context().get_or_create_runner().name != "native":
            physical_plan_scheduler = builder.to_physical_plan_scheduler(get_context().daft_execution_config)
            print_to_file(physical_plan_scheduler.pretty_print(simple, format=format))
        else:
            native_executor = NativeExecutor()
            print_to_file(
                native_executor.pretty_print(builder, get_context().daft_execution_config, simple, format=format)
            )
    else:
        print_to_file(
            "\n \nSet `show_all=True` to also see the Optimized and Physical plans. This will run the query optimizer.",
        )
    return None

explode #

explode(*columns: ColumnInputType) -> DataFrame

Explodes a List column, where every element in each row's List becomes its own row, and all other columns in the DataFrame are duplicated across rows.

If multiple columns are specified, each row must contain the same number of items in each specified column.

Exploding Null values or empty lists will create a single Null entry (see example below).

Parameters:

Name Type Description Default
*columns ColumnInputType

columns to explode

()

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with exploded column

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
>>> import daft
>>> df = daft.from_pydict(
...     {
...         "x": [[1], [2, 3]],
...         "y": [["a"], ["b", "c"]],
...         "z": [
...             [1.0],
...             [2.0, 2.0],
...         ],
...     }
... )
>>> df.explode(col("x"), col("y")).collect()
╭───────┬──────┬───────────────╮
│ x     ┆ y    ┆ z             │
│ ---   ┆ ---  ┆ ---           │
│ Int64 ┆ Utf8 ┆ List[Float64] │
╞═══════╪══════╪═══════════════╡
│ 1     ┆ a    ┆ [1]           │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 2     ┆ b    ┆ [2, 2]        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 3     ┆ c    ┆ [2, 2]        │
╰───────┴──────┴───────────────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
@DataframePublicAPI
def explode(self, *columns: ColumnInputType) -> "DataFrame":
    """Explodes a List column, where every element in each row's List becomes its own row, and all other columns in the DataFrame are duplicated across rows.

    If multiple columns are specified, each row must contain the same number of items in each specified column.

    Exploding Null values or empty lists will create a single Null entry (see example below).

    Args:
        *columns (ColumnInputType): columns to explode

    Returns:
        DataFrame: DataFrame with exploded column

    Examples:
        >>> import daft
        >>> df = daft.from_pydict(
        ...     {
        ...         "x": [[1], [2, 3]],
        ...         "y": [["a"], ["b", "c"]],
        ...         "z": [
        ...             [1.0],
        ...             [2.0, 2.0],
        ...         ],
        ...     }
        ... )
        >>> df.explode(col("x"), col("y")).collect()
        ╭───────┬──────┬───────────────╮
        │ x     ┆ y    ┆ z             │
        │ ---   ┆ ---  ┆ ---           │
        │ Int64 ┆ Utf8 ┆ List[Float64] │
        ╞═══════╪══════╪═══════════════╡
        │ 1     ┆ a    ┆ [1]           │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2     ┆ b    ┆ [2, 2]        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ 3     ┆ c    ┆ [2, 2]        │
        ╰───────┴──────┴───────────────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

    """
    parsed_exprs = self.__column_input_to_expression(columns)
    builder = self._builder.explode(parsed_exprs)
    return DataFrame(builder)

filter #

filter(predicate: Union[Expression, str]) -> DataFrame

Filters rows via a predicate expression, similar to SQL WHERE.

Alias for daft.DataFrame.where.

Parameters:

Name Type Description Default
predicate Expression

expression that keeps row if evaluates to True.

required

Returns:

Name Type Description
DataFrame DataFrame

Filtered DataFrame.

Tip

See also .where(predicate)

Source code in daft/dataframe/dataframe.py
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
@DataframePublicAPI
def filter(self, predicate: Union[Expression, str]) -> "DataFrame":
    """Filters rows via a predicate expression, similar to SQL ``WHERE``.

    Alias for [daft.DataFrame.where][daft.DataFrame.where].

    Args:
        predicate (Expression): expression that keeps row if evaluates to True.

    Returns:
        DataFrame: Filtered DataFrame.

    Tip:
        See also [.where(predicate)][daft.DataFrame.where]

    """
    return self.where(predicate)

groupby #

groupby(
    *group_by: ManyColumnsInputType,
) -> GroupedDataFrame

Performs a GroupBy on the DataFrame for aggregation.

Parameters:

Name Type Description Default
*group_by Union[str, Expression]

columns to group by

()

Returns:

Name Type Description
GroupedDataFrame GroupedDataFrame

DataFrame to Aggregate

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
>>> import daft
>>> from daft import col
>>> df = daft.from_pydict(
...     {
...         "pet": ["cat", "dog", "dog", "cat"],
...         "age": [1, 2, 3, 4],
...         "name": ["Alex", "Jordan", "Sam", "Riley"],
...     }
... )
>>> grouped_df = df.groupby("pet").agg(
...     col("age").min().alias("min_age"),
...     col("age").max().alias("max_age"),
...     col("pet").count().alias("count"),
...     col("name").any_value(),
... )
>>> grouped_df = grouped_df.sort("pet")
>>> grouped_df.show()
╭──────┬─────────┬─────────┬────────┬────────╮
│ pet  ┆ min_age ┆ max_age ┆ count  ┆ name   │
│ ---  ┆ ---     ┆ ---     ┆ ---    ┆ ---    │
│ Utf8 ┆ Int64   ┆ Int64   ┆ UInt64 ┆ Utf8   │
╞══════╪═════════╪═════════╪════════╪════════╡
│ cat  ┆ 1       ┆ 4       ┆ 2      ┆ Alex   │
├╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ dog  ┆ 2       ┆ 3       ┆ 2      ┆ Jordan │
╰──────┴─────────┴─────────┴────────┴────────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
@DataframePublicAPI
def groupby(self, *group_by: ManyColumnsInputType) -> "GroupedDataFrame":
    """Performs a GroupBy on the DataFrame for aggregation.

    Args:
        *group_by (Union[str, Expression]): columns to group by

    Returns:
        GroupedDataFrame: DataFrame to Aggregate

    Examples:
        >>> import daft
        >>> from daft import col
        >>> df = daft.from_pydict(
        ...     {
        ...         "pet": ["cat", "dog", "dog", "cat"],
        ...         "age": [1, 2, 3, 4],
        ...         "name": ["Alex", "Jordan", "Sam", "Riley"],
        ...     }
        ... )
        >>> grouped_df = df.groupby("pet").agg(
        ...     col("age").min().alias("min_age"),
        ...     col("age").max().alias("max_age"),
        ...     col("pet").count().alias("count"),
        ...     col("name").any_value(),
        ... )
        >>> grouped_df = grouped_df.sort("pet")
        >>> grouped_df.show()
        ╭──────┬─────────┬─────────┬────────┬────────╮
        │ pet  ┆ min_age ┆ max_age ┆ count  ┆ name   │
        │ ---  ┆ ---     ┆ ---     ┆ ---    ┆ ---    │
        │ Utf8 ┆ Int64   ┆ Int64   ┆ UInt64 ┆ Utf8   │
        ╞══════╪═════════╪═════════╪════════╪════════╡
        │ cat  ┆ 1       ┆ 4       ┆ 2      ┆ Alex   │
        ├╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
        │ dog  ┆ 2       ┆ 3       ┆ 2      ┆ Jordan │
        ╰──────┴─────────┴─────────┴────────┴────────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

    """
    return GroupedDataFrame(self, ExpressionsProjection(self._wildcard_inputs_to_expressions(group_by)))

intersect #

intersect(other: DataFrame) -> DataFrame

Returns the intersection of two DataFrames.

Parameters:

Name Type Description Default
other DataFrame

DataFrame to intersect with

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the intersection of the two DataFrames

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df1 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 5, 6]})
>>> df2 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 8, 6]})
>>> df = df1.intersect(df2)
>>> df = df.sort("a")
>>> df.show()
╭───────┬───────╮
│ a     ┆ b     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
╰───────┴───────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
@DataframePublicAPI
def intersect(self, other: "DataFrame") -> "DataFrame":
    """Returns the intersection of two DataFrames.

    Args:
        other (DataFrame): DataFrame to intersect with

    Returns:
        DataFrame: DataFrame with the intersection of the two DataFrames

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 5, 6]})
        >>> df2 = daft.from_pydict({"a": [1, 2, 3], "b": [4, 8, 6]})
        >>> df = df1.intersect(df2)
        >>> df = df.sort("a")
        >>> df.show()
        ╭───────┬───────╮
        │ a     ┆ b     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

    """
    builder = self._builder.intersect(other._builder)
    return DataFrame(builder)

intersect_all #

intersect_all(other: DataFrame) -> DataFrame

Returns the intersection of two DataFrames, including duplicates.

Parameters:

Name Type Description Default
other DataFrame

DataFrame to intersect with

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the intersection of the two DataFrames, including duplicates

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df1 = daft.from_pydict({"a": [1, 2, 2], "b": [4, 6, 6]})
>>> df2 = daft.from_pydict({"a": [1, 1, 2, 2], "b": [4, 4, 6, 6]})
>>> df1.intersect_all(df2).sort("a").collect()
╭───────┬───────╮
│ a     ┆ b     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 6     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 6     │
╰───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
@DataframePublicAPI
def intersect_all(self, other: "DataFrame") -> "DataFrame":
    """Returns the intersection of two DataFrames, including duplicates.

    Args:
        other (DataFrame): DataFrame to intersect with

    Returns:
        DataFrame: DataFrame with the intersection of the two DataFrames, including duplicates

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"a": [1, 2, 2], "b": [4, 6, 6]})
        >>> df2 = daft.from_pydict({"a": [1, 1, 2, 2], "b": [4, 4, 6, 6]})
        >>> df1.intersect_all(df2).sort("a").collect()
        ╭───────┬───────╮
        │ a     ┆ b     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 6     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

    """
    builder = self._builder.intersect_all(other._builder)
    return DataFrame(builder)

into_partitions #

into_partitions(num: int) -> DataFrame

Splits or coalesces DataFrame to num partitions. Order is preserved.

This will naively greedily split partitions in a round-robin fashion to hit the targeted number of partitions. The number of rows/size in a given partition is not taken into account during the splitting.

Parameters:

Name Type Description Default
num int

number of target partitions.

required

Returns:

Name Type Description
DataFrame DataFrame

Dataframe with num partitions.

Examples:

1
2
3
4
5
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> df_with_5_partitions = df.into_partitions(5)
>>> df_with_5_partitions.num_partitions()
5
Source code in daft/dataframe/dataframe.py
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
@DataframePublicAPI
def into_partitions(self, num: int) -> "DataFrame":
    """Splits or coalesces DataFrame to ``num`` partitions. Order is preserved.

    This will naively greedily split partitions in a round-robin fashion to hit the targeted number of partitions.
    The number of rows/size in a given partition is not taken into account during the splitting.

    Args:
        num (int): number of target partitions.

    Returns:
        DataFrame: Dataframe with `num` partitions.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> df_with_5_partitions = df.into_partitions(5)
        >>> df_with_5_partitions.num_partitions()
        5
    """
    builder = self._builder.into_partitions(num)
    return DataFrame(builder)

iter_partitions #

iter_partitions(
    results_buffer_size: Union[
        Optional[int], Literal["num_cpus"]
    ] = "num_cpus",
) -> Iterator[
    Union[MicroPartition, ObjectRef[MicroPartition]]
]

Begin executing this dataframe and return an iterator over the partitions.

Each partition will be returned as a daft.recordbatch object (if using Python runner backend) or a ray ObjectRef (if using Ray runner backend).

Parameters:

Name Type Description Default
results_buffer_size Union[Optional[int], Literal['num_cpus']]

how many partitions to allow in the results buffer (defaults to the total number of CPUs available on the machine).

'num_cpus'
A quick note on configuring asynchronous/parallel execution using results_buffer_size.

The results_buffer_size kwarg controls how many results Daft will allow to be in the buffer while iterating. Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.

  • Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
  • Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
  • Setting this value to None means the iterator will consume as much resources as it deems appropriate per-iteration

The default value is the total number of CPUs available on the current machine.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
>>> import daft
>>>
>>> daft.context.set_runner_ray()
>>>
>>> df = daft.from_pydict({"foo": [1, 2, 3], "bar": ["a", "b", "c"]}).into_partitions(2)
>>> for part in df.iter_partitions():
...     print(part)
MicroPartition with 2 rows:
TableState: Loaded. 1 tables
╭───────┬──────╮
│ foo   ┆ bar  │
│ ---   ┆ ---  │
│ Int64 ┆ Utf8 │
╞═══════╪══════╡
│ 1     ┆ a    │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ 2     ┆ b    │
╰───────┴──────╯


Statistics: missing

MicroPartition with 1 rows:
TableState: Loaded. 1 tables
╭───────┬──────╮
│ foo   ┆ bar  │
│ ---   ┆ ---  │
│ Int64 ┆ Utf8 │
╞═══════╪══════╡
│ 3     ┆ c    │
╰───────┴──────╯


Statistics: missing
Source code in daft/dataframe/dataframe.py
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
@DataframePublicAPI
def iter_partitions(
    self, results_buffer_size: Union[Optional[int], Literal["num_cpus"]] = "num_cpus"
) -> Iterator[Union[MicroPartition, "ray.ObjectRef[MicroPartition]"]]:
    """Begin executing this dataframe and return an iterator over the partitions.

    Each partition will be returned as a daft.recordbatch object (if using Python runner backend)
    or a ray ObjectRef (if using Ray runner backend).

    Args:
        results_buffer_size: how many partitions to allow in the results buffer (defaults to the total number of CPUs
            available on the machine).

    Note: A quick note on configuring asynchronous/parallel execution using `results_buffer_size`.
        The `results_buffer_size` kwarg controls how many results Daft will allow to be in the buffer while iterating.
        Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.

        * Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
        * Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
        * Setting this value to `None` means the iterator will consume as much resources as it deems appropriate per-iteration

        The default value is the total number of CPUs available on the current machine.

    Examples:
        >>> import daft
        >>>
        >>> daft.context.set_runner_ray()  # doctest: +SKIP
        >>>
        >>> df = daft.from_pydict({"foo": [1, 2, 3], "bar": ["a", "b", "c"]}).into_partitions(2)
        >>> for part in df.iter_partitions():
        ...     print(part)  # doctest: +SKIP
        MicroPartition with 2 rows:
        TableState: Loaded. 1 tables
        ╭───────┬──────╮
        │ foo   ┆ bar  │
        │ ---   ┆ ---  │
        │ Int64 ┆ Utf8 │
        ╞═══════╪══════╡
        │ 1     ┆ a    │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ 2     ┆ b    │
        ╰───────┴──────╯
        <BLANKLINE>
        <BLANKLINE>
        Statistics: missing
        <BLANKLINE>
        MicroPartition with 1 rows:
        TableState: Loaded. 1 tables
        ╭───────┬──────╮
        │ foo   ┆ bar  │
        │ ---   ┆ ---  │
        │ Int64 ┆ Utf8 │
        ╞═══════╪══════╡
        │ 3     ┆ c    │
        ╰───────┴──────╯
        <BLANKLINE>
        <BLANKLINE>
        Statistics: missing
        <BLANKLINE>
    """
    if results_buffer_size == "num_cpus":
        results_buffer_size = multiprocessing.cpu_count()
    elif results_buffer_size is not None and not results_buffer_size > 0:
        raise ValueError(f"Provided `results_buffer_size` value must be > 0, received: {results_buffer_size}")

    if self._result is not None:
        # If the dataframe has already finished executing,
        # use the precomputed results.
        for mat_result in self._result.values():
            yield mat_result.partition()

    else:
        # Execute the dataframe in a streaming fashion.
        context = get_context()
        results_iter = context.get_or_create_runner().run_iter(
            self._builder, results_buffer_size=results_buffer_size
        )
        for result in results_iter:
            yield result.partition()

iter_rows #

iter_rows(
    results_buffer_size: Union[
        Optional[int], Literal["num_cpus"]
    ] = "num_cpus",
    column_format: Literal["python", "arrow"] = "python",
) -> Iterator[Dict[str, Any]]

Return an iterator of rows for this dataframe.

Each row will be a Python dictionary of the form { "key" : value, ...}. If you are instead looking to iterate over entire partitions of data, see df.iter_partitions().

By default, Daft will convert the columns to Python lists for easy consumption. Datatypes with Python equivalents will be converted accordingly, e.g. timestamps to datetime, tensors to numpy arrays. For nested data such as List or Struct arrays, however, this can be expensive. You may wish to set column_format to "arrow" such that the nested data is returned as Arrow scalars.

Parameters:

Name Type Description Default
results_buffer_size Union[Optional[int], Literal['num_cpus']]

how many partitions to allow in the results buffer (defaults to the total number of CPUs available on the machine).

'num_cpus'
column_format Literal['python', 'arrow']

the format of the columns to iterate over. One of "python" or "arrow". Defaults to "python".

'python'
A quick note on configuring asynchronous/parallel execution using results_buffer_size.

The results_buffer_size kwarg controls how many results Daft will allow to be in the buffer while iterating. Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.

  • Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
  • Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
  • Setting this value to None means the iterator will consume as much resources as it deems appropriate per-iteration

The default value is the total number of CPUs available on the current machine.

Examples:

1
2
3
4
5
6
7
8
>>> import daft
>>>
>>> df = daft.from_pydict({"foo": [1, 2, 3], "bar": ["a", "b", "c"]})
>>> for row in df.iter_rows():
...     print(row)
{'foo': 1, 'bar': 'a'}
{'foo': 2, 'bar': 'b'}
{'foo': 3, 'bar': 'c'}

See also df.iter_partitions(): iterator over entire partitions instead of single rows

Source code in daft/dataframe/dataframe.py
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
@DataframePublicAPI
def iter_rows(
    self,
    results_buffer_size: Union[Optional[int], Literal["num_cpus"]] = "num_cpus",
    column_format: Literal["python", "arrow"] = "python",
) -> Iterator[Dict[str, Any]]:
    """Return an iterator of rows for this dataframe.

    Each row will be a Python dictionary of the form `{ "key" : value, ...}`. If you are instead looking to iterate over
    entire partitions of data, see [`df.iter_partitions()`][daft.DataFrame.iter_partitions].

    By default, Daft will convert the columns to Python lists for easy consumption. Datatypes with Python equivalents will be converted accordingly, e.g. timestamps to datetime, tensors to numpy arrays.
    For nested data such as List or Struct arrays, however, this can be expensive. You may wish to set `column_format` to "arrow" such that the nested data is returned as Arrow scalars.

    Args:
        results_buffer_size: how many partitions to allow in the results buffer (defaults to the total number of CPUs
            available on the machine).
        column_format: the format of the columns to iterate over. One of "python" or "arrow". Defaults to "python".

    Note: A quick note on configuring asynchronous/parallel execution using `results_buffer_size`.
        The `results_buffer_size` kwarg controls how many results Daft will allow to be in the buffer while iterating.
        Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.

        * Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
        * Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
        * Setting this value to `None` means the iterator will consume as much resources as it deems appropriate per-iteration

        The default value is the total number of CPUs available on the current machine.

    Examples:
        >>> import daft
        >>>
        >>> df = daft.from_pydict({"foo": [1, 2, 3], "bar": ["a", "b", "c"]})
        >>> for row in df.iter_rows():
        ...     print(row)
        {'foo': 1, 'bar': 'a'}
        {'foo': 2, 'bar': 'b'}
        {'foo': 3, 'bar': 'c'}

    !!! tip "See also [`df.iter_partitions()`][daft.DataFrame.iter_partitions]: iterator over entire partitions instead of single rows"
    """
    if results_buffer_size == "num_cpus":
        results_buffer_size = multiprocessing.cpu_count()

    def arrow_iter_rows(table: "pyarrow.Table") -> Iterator[Dict[str, Any]]:
        columns = table.columns
        for i in range(len(table)):
            row = {col._name: col[i] for col in columns}
            yield row

    def python_iter_rows(pydict: Dict[str, List[Any]], num_rows: int) -> Iterator[Dict[str, Any]]:
        for i in range(num_rows):
            row = {key: value[i] for (key, value) in pydict.items()}
            yield row

    if self._result is not None:
        # If the dataframe has already finished executing,
        # use the precomputed results.
        if column_format == "python":
            yield from python_iter_rows(self.to_pydict(), len(self))
        elif column_format == "arrow":
            yield from arrow_iter_rows(self.to_arrow())
        else:
            raise ValueError(
                f"Unsupported column_format: {column_format}, supported formats are 'python' and 'arrow'"
            )
    else:
        # Execute the dataframe in a streaming fashion.
        context = get_context()
        partitions_iter = context.get_or_create_runner().run_iter_tables(
            self._builder, results_buffer_size=results_buffer_size
        )

        # Iterate through partitions.
        for partition in partitions_iter:
            if column_format == "python":
                yield from python_iter_rows(partition.to_pydict(), len(partition))
            elif column_format == "arrow":
                yield from arrow_iter_rows(partition.to_arrow())
            else:
                raise ValueError(
                    f"Unsupported column_format: {column_format}, supported formats are 'python' and 'arrow'"
                )

join #

join(
    other: DataFrame,
    on: Optional[
        Union[List[ColumnInputType], ColumnInputType]
    ] = None,
    left_on: Optional[
        Union[List[ColumnInputType], ColumnInputType]
    ] = None,
    right_on: Optional[
        Union[List[ColumnInputType], ColumnInputType]
    ] = None,
    how: Literal[
        "inner",
        "inner",
        "left",
        "right",
        "outer",
        "anti",
        "semi",
        "cross",
    ] = "inner",
    strategy: Optional[
        Literal["hash", "sort_merge", "broadcast"]
    ] = None,
    prefix: Optional[str] = None,
    suffix: Optional[str] = None,
) -> DataFrame

Column-wise join of the current DataFrame with an other DataFrame, similar to a SQL JOIN.

If the two DataFrames have duplicate non-join key column names, "right." will be prepended to the conflicting right columns. You can change the behavior by passing either (or both) prefix or suffix to the function. If prefix is passed, it will be prepended to the conflicting right columns. If suffix is passed, it will be appended to the conflicting right columns.

Parameters:

Name Type Description Default
other DataFrame

the right DataFrame to join on.

required
on Optional[Union[List[ColumnInputType], ColumnInputType]]

key or keys to join on [use if the keys on the left and right side match.]. Defaults to None.

None
left_on Optional[Union[List[ColumnInputType], ColumnInputType]]

key or keys to join on left DataFrame. Defaults to None.

None
right_on Optional[Union[List[ColumnInputType], ColumnInputType]]

key or keys to join on right DataFrame. Defaults to None.

None
how str

what type of join to perform; currently "inner", "left", "right", "outer", "anti", "semi", and "cross" are supported. Defaults to "inner".

'inner'
strategy Optional[str]

The join strategy (algorithm) to use; currently "hash", "sort_merge", "broadcast", and None are supported, where None chooses the join strategy automatically during query optimization. The default is None.

None
suffix Optional[str]

Suffix to add to the column names in case of a name collision. Defaults to "".

None
prefix Optional[str]

Prefix to add to the column names in case of a name collision. Defaults to "right.".

None

Returns:

Name Type Description
DataFrame DataFrame

Joined DataFrame.

Raises:

Type Description
ValueError

if on is passed in and left_on or right_on is not None.

ValueError

if on is None but both left_on and right_on are not defined.

Note

Although self joins are supported, we currently duplicate the logical plan for the right side and recompute the entire tree. Caching for this is on the roadmap.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> from daft import col
>>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
>>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
>>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10])
>>> joined_df.show()
╭──────┬───────┬─────────╮
│ a    ┆ b     ┆ right.b │
│ ---  ┆ ---   ┆ ---     │
│ Utf8 ┆ Int64 ┆ Int64   │
╞══════╪═══════╪═════════╡
│ x    ┆ 2     ┆ 20      │
├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ y    ┆ 3     ┆ 30      │
╰──────┴───────┴─────────╯

(Showing first 2 of 2 rows)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> from daft import col
>>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
>>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
>>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10], prefix="right_")
>>> joined_df.show()
╭──────┬───────┬─────────╮
│ a    ┆ b     ┆ right_b │
│ ---  ┆ ---   ┆ ---     │
│ Utf8 ┆ Int64 ┆ Int64   │
╞══════╪═══════╪═════════╡
│ x    ┆ 2     ┆ 20      │
├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ y    ┆ 3     ┆ 30      │
╰──────┴───────┴─────────╯

(Showing first 2 of 2 rows)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> from daft import col
>>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
>>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
>>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10], suffix="_right")
>>> joined_df.show()
╭──────┬───────┬─────────╮
│ a    ┆ b     ┆ b_right │
│ ---  ┆ ---   ┆ ---     │
│ Utf8 ┆ Int64 ┆ Int64   │
╞══════╪═══════╪═════════╡
│ x    ┆ 2     ┆ 20      │
├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ y    ┆ 3     ┆ 30      │
╰──────┴───────┴─────────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
@DataframePublicAPI
def join(
    self,
    other: "DataFrame",
    on: Optional[Union[List[ColumnInputType], ColumnInputType]] = None,
    left_on: Optional[Union[List[ColumnInputType], ColumnInputType]] = None,
    right_on: Optional[Union[List[ColumnInputType], ColumnInputType]] = None,
    how: Literal["inner", "inner", "left", "right", "outer", "anti", "semi", "cross"] = "inner",
    strategy: Optional[Literal["hash", "sort_merge", "broadcast"]] = None,
    prefix: Optional[str] = None,
    suffix: Optional[str] = None,
) -> "DataFrame":
    """Column-wise join of the current DataFrame with an ``other`` DataFrame, similar to a SQL ``JOIN``.

    If the two DataFrames have duplicate non-join key column names, "right." will be prepended to the conflicting right columns. You can change the behavior by passing either (or both) `prefix` or `suffix` to the function.
    If `prefix` is passed, it will be prepended to the conflicting right columns. If `suffix` is passed, it will be appended to the conflicting right columns.

    Args:
        other (DataFrame): the right DataFrame to join on.
        on (Optional[Union[List[ColumnInputType], ColumnInputType]], optional): key or keys to join on [use if the keys on the left and right side match.]. Defaults to None.
        left_on (Optional[Union[List[ColumnInputType], ColumnInputType]], optional): key or keys to join on left DataFrame. Defaults to None.
        right_on (Optional[Union[List[ColumnInputType], ColumnInputType]], optional): key or keys to join on right DataFrame. Defaults to None.
        how (str, optional): what type of join to perform; currently "inner", "left", "right", "outer", "anti", "semi", and "cross" are supported. Defaults to "inner".
        strategy (Optional[str]): The join strategy (algorithm) to use; currently "hash", "sort_merge", "broadcast", and None are supported, where None
            chooses the join strategy automatically during query optimization. The default is None.
        suffix (Optional[str], optional): Suffix to add to the column names in case of a name collision. Defaults to "".
        prefix (Optional[str], optional): Prefix to add to the column names in case of a name collision. Defaults to "right.".

    Returns:
        DataFrame: Joined DataFrame.

    Raises:
        ValueError: if `on` is passed in and `left_on` or `right_on` is not None.
        ValueError: if `on` is None but both `left_on` and `right_on` are not defined.

    Note:
        Although self joins are supported, we currently duplicate the logical plan for the right side
        and recompute the entire tree. Caching for this is on the roadmap.

    Examples:
        >>> import daft
        >>> from daft import col
        >>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
        >>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
        >>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10])
        >>> joined_df.show()
        ╭──────┬───────┬─────────╮
        │ a    ┆ b     ┆ right.b │
        │ ---  ┆ ---   ┆ ---     │
        │ Utf8 ┆ Int64 ┆ Int64   │
        ╞══════╪═══════╪═════════╡
        │ x    ┆ 2     ┆ 20      │
        ├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
        │ y    ┆ 3     ┆ 30      │
        ╰──────┴───────┴─────────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

        >>> import daft
        >>> from daft import col
        >>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
        >>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
        >>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10], prefix="right_")
        >>> joined_df.show()
        ╭──────┬───────┬─────────╮
        │ a    ┆ b     ┆ right_b │
        │ ---  ┆ ---   ┆ ---     │
        │ Utf8 ┆ Int64 ┆ Int64   │
        ╞══════╪═══════╪═════════╡
        │ x    ┆ 2     ┆ 20      │
        ├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
        │ y    ┆ 3     ┆ 30      │
        ╰──────┴───────┴─────────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

        >>> import daft
        >>> from daft import col
        >>> df1 = daft.from_pydict({"a": ["w", "x", "y"], "b": [1, 2, 3]})
        >>> df2 = daft.from_pydict({"a": ["x", "y", "z"], "b": [20, 30, 40]})
        >>> joined_df = df1.join(df2, left_on=[col("a"), col("b")], right_on=[col("a"), col("b") / 10], suffix="_right")
        >>> joined_df.show()
        ╭──────┬───────┬─────────╮
        │ a    ┆ b     ┆ b_right │
        │ ---  ┆ ---   ┆ ---     │
        │ Utf8 ┆ Int64 ┆ Int64   │
        ╞══════╪═══════╪═════════╡
        │ x    ┆ 2     ┆ 20      │
        ├╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
        │ y    ┆ 3     ┆ 30      │
        ╰──────┴───────┴─────────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)
    """
    if how == "cross":
        if any(side_on is not None for side_on in [on, left_on, right_on]):
            raise ValueError("In a cross join, `on`, `left_on`, and `right_on` cannot be set")

        left_on = []
        right_on = []
    elif on is None:
        if left_on is None or right_on is None:
            raise ValueError("If `on` is None then both `left_on` and `right_on` must not be None")
    else:
        if left_on is not None or right_on is not None:
            raise ValueError("If `on` is not None then both `left_on` and `right_on` must be None")
        left_on = on
        right_on = on

    join_type = JoinType.from_join_type_str(how)
    join_strategy = JoinStrategy.from_join_strategy_str(strategy) if strategy is not None else None

    if join_strategy == JoinStrategy.SortMerge and join_type != JoinType.Inner:
        raise ValueError("Sort merge join only supports inner joins")
    elif join_strategy == JoinStrategy.Broadcast and join_type == JoinType.Outer:
        raise ValueError("Broadcast join does not support outer joins")

    left_exprs = self.__column_input_to_expression(tuple(left_on) if isinstance(left_on, list) else (left_on,))
    right_exprs = self.__column_input_to_expression(tuple(right_on) if isinstance(right_on, list) else (right_on,))
    builder = self._builder.join(
        other._builder,
        left_on=left_exprs,
        right_on=right_exprs,
        how=join_type,
        strategy=join_strategy,
        prefix=prefix,
        suffix=suffix,
    )
    return DataFrame(builder)

limit #

limit(num: int) -> DataFrame

Limits the rows in the DataFrame to the first N rows, similar to a SQL LIMIT.

Parameters:

Name Type Description Default
num int

maximum rows to allow.

required
eager bool

whether to maximize for latency (time to first result) by eagerly executing only one partition at a time, or throughput by executing multiple limits at a time

required

Returns:

Name Type Description
DataFrame DataFrame

Limited DataFrame

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
>>> import daft
>>> df = df = daft.from_pydict({"x": [1, 2, 3, 4, 5, 6, 7]})
>>> df_limited = df.limit(5)  # returns 5 rows
>>> df_limited.show()
╭───────╮
│ x     │
│ ---   │
│ Int64 │
╞═══════╡
│ 1     │
├╌╌╌╌╌╌╌┤
│ 2     │
├╌╌╌╌╌╌╌┤
│ 3     │
├╌╌╌╌╌╌╌┤
│ 4     │
├╌╌╌╌╌╌╌┤
│ 5     │
╰───────╯

(Showing first 5 of 5 rows)
Source code in daft/dataframe/dataframe.py
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
@DataframePublicAPI
def limit(self, num: int) -> "DataFrame":
    """Limits the rows in the DataFrame to the first ``N`` rows, similar to a SQL ``LIMIT``.

    Args:
        num (int): maximum rows to allow.
        eager (bool): whether to maximize for latency (time to first result) by eagerly executing
            only one partition at a time, or throughput by executing multiple limits at a time

    Returns:
        DataFrame: Limited DataFrame

    Examples:
        >>> import daft
        >>> df = df = daft.from_pydict({"x": [1, 2, 3, 4, 5, 6, 7]})
        >>> df_limited = df.limit(5)  # returns 5 rows
        >>> df_limited.show()
        ╭───────╮
        │ x     │
        │ ---   │
        │ Int64 │
        ╞═══════╡
        │ 1     │
        ├╌╌╌╌╌╌╌┤
        │ 2     │
        ├╌╌╌╌╌╌╌┤
        │ 3     │
        ├╌╌╌╌╌╌╌┤
        │ 4     │
        ├╌╌╌╌╌╌╌┤
        │ 5     │
        ╰───────╯
        <BLANKLINE>
        (Showing first 5 of 5 rows)

    """
    builder = self._builder.limit(num, eager=False)
    return DataFrame(builder)

max #

max(*cols: ColumnInputType) -> DataFrame

Performs a global max on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to max

()

Returns: DataFrame: Globally aggregated max. Should be a single row.

Source code in daft/dataframe/dataframe.py
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
@DataframePublicAPI
def max(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global max on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to max
    Returns:
        DataFrame: Globally aggregated max. Should be a single row.
    """
    return self._apply_agg_fn(Expression.max, cols)

mean #

mean(*cols: ColumnInputType) -> DataFrame

Performs a global mean on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to mean

()

Returns: DataFrame: Globally aggregated mean. Should be a single row.

Source code in daft/dataframe/dataframe.py
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
@DataframePublicAPI
def mean(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global mean on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to mean
    Returns:
        DataFrame: Globally aggregated mean. Should be a single row.
    """
    return self._apply_agg_fn(Expression.mean, cols)

melt #

melt(
    ids: ManyColumnsInputType,
    values: ManyColumnsInputType = [],
    variable_name: str = "variable",
    value_name: str = "value",
) -> DataFrame

Alias for unpivot.

Tip

See also unpivot

Source code in daft/dataframe/dataframe.py
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
@DataframePublicAPI
def melt(
    self,
    ids: ManyColumnsInputType,
    values: ManyColumnsInputType = [],
    variable_name: str = "variable",
    value_name: str = "value",
) -> "DataFrame":
    """Alias for unpivot.

    Tip:
        See also [unpivot][daft.DataFrame.unpivot]
    """
    return self.unpivot(ids, values, variable_name, value_name)

min #

min(*cols: ColumnInputType) -> DataFrame

Performs a global min on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to min

()

Returns: DataFrame: Globally aggregated min. Should be a single row.

Source code in daft/dataframe/dataframe.py
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
@DataframePublicAPI
def min(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global min on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to min
    Returns:
        DataFrame: Globally aggregated min. Should be a single row.
    """
    return self._apply_agg_fn(Expression.min, cols)

num_partitions #

num_partitions() -> int
Source code in daft/dataframe/dataframe.py
296
297
298
299
300
def num_partitions(self) -> int:
    # We need to run the optimizer since that could change the number of partitions
    return (
        self.__builder.optimize().to_physical_plan_scheduler(get_context().daft_execution_config).num_partitions()
    )

pipe #

pipe(
    function: Callable[Concatenate[DataFrame, P], T],
    *args: args,
    **kwargs: kwargs,
) -> T

Apply the function to this DataFrame.

Parameters:

Name Type Description Default
function Callable[Concatenate[DataFrame, P], T]

Function to apply.

required
*args args

Positional arguments to pass to the function.

()
**kwargs kwargs

Keyword arguments to pass to the function.

{}

Returns:

Type Description
T

Result of applying the function on this DataFrame.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
>>> import daft
>>>
>>> df = daft.from_pydict({"x": [1, 2, 3]})
>>>
>>> def double(df, column: str):
...     return df.select((df[column] * df[column]).alias(column))
>>>
>>> df.pipe(double, "x").show()
╭───────╮
│ x     │
│ ---   │
│ Int64 │
╞═══════╡
│ 1     │
├╌╌╌╌╌╌╌┤
│ 4     │
├╌╌╌╌╌╌╌┤
│ 9     │
╰───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
def pipe(
    self,
    function: Callable[Concatenate["DataFrame", P], T],
    *args: P.args,
    **kwargs: P.kwargs,
) -> T:
    """Apply the function to this DataFrame.

    Args:
        function (Callable[Concatenate["DataFrame", P], T]): Function to apply.
        *args (P.args): Positional arguments to pass to the function.
        **kwargs (P.kwargs): Keyword arguments to pass to the function.

    Returns:
        Result of applying the function on this DataFrame.

    Examples:
        >>> import daft
        >>>
        >>> df = daft.from_pydict({"x": [1, 2, 3]})
        >>>
        >>> def double(df, column: str):
        ...     return df.select((df[column] * df[column]).alias(column))
        >>>
        >>> df.pipe(double, "x").show()
        ╭───────╮
        │ x     │
        │ ---   │
        │ Int64 │
        ╞═══════╡
        │ 1     │
        ├╌╌╌╌╌╌╌┤
        │ 4     │
        ├╌╌╌╌╌╌╌┤
        │ 9     │
        ╰───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    return function(self, *args, **kwargs)

pivot #

pivot(
    group_by: ManyColumnsInputType,
    pivot_col: ColumnInputType,
    value_col: ColumnInputType,
    agg_fn: str,
    names: Optional[List[str]] = None,
) -> DataFrame

Pivots a column of the DataFrame and performs an aggregation on the values.

Parameters:

Name Type Description Default
group_by ManyColumnsInputType

columns to group by

required
pivot_col Union[str, Expression]

column to pivot

required
value_col Union[str, Expression]

column to aggregate

required
agg_fn str

aggregation function to apply

required
names Optional[List[str]]

names of the pivoted columns

None

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with pivoted columns

Note

You may wish to provide a list of distinct values to pivot on, which is more efficient as it avoids a distinct operation. Without this list, Daft will perform a distinct operation on the pivot column to determine the unique values to pivot on.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
>>> import daft
>>> data = {
...     "id": [1, 2, 3, 4],
...     "version": ["3.8", "3.8", "3.9", "3.9"],
...     "platform": ["macos", "macos", "macos", "windows"],
...     "downloads": [100, 200, 150, 250],
... }
>>> df = daft.from_pydict(data)
>>> df = df.pivot("version", "platform", "downloads", "sum")
>>>
>>> df = df.sort("version").select("version", "windows", "macos")
>>> df.show()
╭─────────┬─────────┬───────╮
│ version ┆ windows ┆ macos │
│ ---     ┆ ---     ┆ ---   │
│ Utf8    ┆ Int64   ┆ Int64 │
╞═════════╪═════════╪═══════╡
│ 3.8     ┆ None    ┆ 300   │
├╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3.9     ┆ 250     ┆ 150   │
╰─────────┴─────────┴───────╯

(Showing first 2 of 2 rows)
Source code in daft/dataframe/dataframe.py
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
@DataframePublicAPI
def pivot(
    self,
    group_by: ManyColumnsInputType,
    pivot_col: ColumnInputType,
    value_col: ColumnInputType,
    agg_fn: str,
    names: Optional[List[str]] = None,
) -> "DataFrame":
    """Pivots a column of the DataFrame and performs an aggregation on the values.

    Args:
        group_by (ManyColumnsInputType): columns to group by
        pivot_col (Union[str, Expression]): column to pivot
        value_col (Union[str, Expression]): column to aggregate
        agg_fn (str): aggregation function to apply
        names (Optional[List[str]]): names of the pivoted columns

    Returns:
        DataFrame: DataFrame with pivoted columns

    Note:
        You may wish to provide a list of distinct values to pivot on, which is more efficient as it avoids
        a distinct operation. Without this list, Daft will perform a distinct operation on the pivot column to
        determine the unique values to pivot on.

    Examples:
        >>> import daft
        >>> data = {
        ...     "id": [1, 2, 3, 4],
        ...     "version": ["3.8", "3.8", "3.9", "3.9"],
        ...     "platform": ["macos", "macos", "macos", "windows"],
        ...     "downloads": [100, 200, 150, 250],
        ... }
        >>> df = daft.from_pydict(data)
        >>> df = df.pivot("version", "platform", "downloads", "sum")
        >>>
        >>> df = df.sort("version").select("version", "windows", "macos")
        >>> df.show()
        ╭─────────┬─────────┬───────╮
        │ version ┆ windows ┆ macos │
        │ ---     ┆ ---     ┆ ---   │
        │ Utf8    ┆ Int64   ┆ Int64 │
        ╞═════════╪═════════╪═══════╡
        │ 3.8     ┆ None    ┆ 300   │
        ├╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3.9     ┆ 250     ┆ 150   │
        ╰─────────┴─────────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)


    """
    group_by_expr = column_inputs_to_expressions(group_by)
    [pivot_col_expr, value_col_expr] = column_inputs_to_expressions([pivot_col, value_col])
    agg_expr = self._map_agg_string_to_expr(value_col_expr, agg_fn)

    if names is None:
        names = self.select(pivot_col_expr).distinct().to_pydict()[pivot_col_expr.name()]
        names = [str(x) for x in names]
    builder = self._builder.pivot(group_by_expr, pivot_col_expr, value_col_expr, agg_expr, names)
    return DataFrame(builder)

repartition #

repartition(
    num: Optional[int], *partition_by: ColumnInputType
) -> DataFrame

Repartitions DataFrame to num partitions.

If columns are passed in, then DataFrame will be repartitioned by those, otherwise random repartitioning will occur.

Parameters:

Name Type Description Default
num Optional[int]

Number of target partitions; if None, the number of partitions will not be changed.

required
*partition_by Union[str, Expression]

Optional columns to partition by.

()

Returns:

Name Type Description
DataFrame DataFrame

Repartitioned DataFrame.

This function will globally shuffle your data, which is potentially a very expensive operation.

If instead you merely wish to "split" or "coalesce" partitions to obtain a target number of partitions, you mean instead wish to consider using DataFrame.into_partitions which avoids shuffling of data in favor of splitting/coalescing adjacent partitions where appropriate.

Examples:

1
2
3
4
5
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> repartitioned_df = df.repartition(3)
>>> repartitioned_df.num_partitions()
3
Source code in daft/dataframe/dataframe.py
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
@DataframePublicAPI
def repartition(self, num: Optional[int], *partition_by: ColumnInputType) -> "DataFrame":
    """Repartitions DataFrame to ``num`` partitions.

    If columns are passed in, then DataFrame will be repartitioned by those, otherwise
    random repartitioning will occur.

    Args:
        num (Optional[int]): Number of target partitions; if None, the number of partitions will not be changed.
        *partition_by (Union[str, Expression]): Optional columns to partition by.

    Returns:
        DataFrame: Repartitioned DataFrame.

    Note: This function will globally shuffle your data, which is potentially a very expensive operation.
        If instead you merely wish to "split" or "coalesce" partitions to obtain a target number of partitions,
        you mean instead wish to consider using [DataFrame.into_partitions][daft.DataFrame.into_partitions] which
        avoids shuffling of data in favor of splitting/coalescing adjacent partitions where appropriate.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> repartitioned_df = df.repartition(3)
        >>> repartitioned_df.num_partitions()
        3

    """
    if len(partition_by) == 0:
        warnings.warn(
            "No columns specified for repartition, so doing a random shuffle. If you do not require rebalancing of "
            "partitions, you may instead prefer using `df.into_partitions(N)` which is a cheaper operation that "
            "avoids shuffling data."
        )
        builder = self._builder.random_shuffle(num)
    else:
        builder = self._builder.hash_repartition(num, self.__column_input_to_expression(partition_by))
    return DataFrame(builder)

sample #

sample(
    fraction: float,
    with_replacement: bool = False,
    seed: Optional[int] = None,
) -> DataFrame

Samples a fraction of rows from the DataFrame.

Parameters:

Name Type Description Default
fraction float

fraction of rows to sample.

required
with_replacement bool

whether to sample with replacement. Defaults to False.

False
seed Optional[int]

random seed. Defaults to None.

None

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with a fraction of rows.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> sampled_df = df.sample(0.5)
>>> # Samples will vary from output to output
>>> # here is a sample output
>>> # ╭───────┬───────┬───────╮
>>> # │ x     ┆ y     ┆ z     │
>>> # │ ---   ┆ ---   ┆ ---   │
>>> # │ Int64 ┆ Int64 ┆ Int64 │
>>> # |═══════╪═══════╪═══════╡
>>> # │ 2     ┆ 5     ┆ 8     │
>>> # ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
>>> # │ 3     ┆ 6     ┆ 9     │
>>> # ╰───────┴───────┴───────╯
Source code in daft/dataframe/dataframe.py
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
@DataframePublicAPI
def sample(
    self,
    fraction: float,
    with_replacement: bool = False,
    seed: Optional[int] = None,
) -> "DataFrame":
    """Samples a fraction of rows from the DataFrame.

    Args:
        fraction (float): fraction of rows to sample.
        with_replacement (bool, optional): whether to sample with replacement. Defaults to False.
        seed (Optional[int], optional): random seed. Defaults to None.

    Returns:
        DataFrame: DataFrame with a fraction of rows.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> sampled_df = df.sample(0.5)
        >>> # Samples will vary from output to output
        >>> # here is a sample output
        >>> # ╭───────┬───────┬───────╮
        >>> # │ x     ┆ y     ┆ z     │
        >>> # │ ---   ┆ ---   ┆ ---   │
        >>> # │ Int64 ┆ Int64 ┆ Int64 │
        >>> # |═══════╪═══════╪═══════╡
        >>> # │ 2     ┆ 5     ┆ 8     │
        >>> # ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        >>> # │ 3     ┆ 6     ┆ 9     │
        >>> # ╰───────┴───────┴───────╯
    """
    if fraction < 0.0 or fraction > 1.0:
        raise ValueError(f"fraction should be between 0.0 and 1.0, but got {fraction}")

    builder = self._builder.sample(fraction, with_replacement, seed)
    return DataFrame(builder)

schema #

schema() -> Schema

Returns the Schema of the DataFrame, which provides information about each column, as a Python object.

Returns:

Name Type Description
Schema Schema

schema of the DataFrame

Source code in daft/dataframe/dataframe.py
302
303
304
305
306
307
308
309
@DataframePublicAPI
def schema(self) -> Schema:
    """Returns the Schema of the DataFrame, which provides information about each column, as a Python object.

    Returns:
        Schema: schema of the DataFrame
    """
    return self.__builder.schema()

select #

select(*columns: ColumnInputType) -> DataFrame

Creates a new DataFrame from the provided expressions, similar to a SQL SELECT.

Parameters:

Name Type Description Default
*columns Union[str, Expression]

columns to select from the current DataFrame

()

Returns:

Name Type Description
DataFrame DataFrame

new DataFrame that will select the passed in columns

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> df = df.select("x", daft.col("y"), daft.col("z") + 1)
>>> df.show()
╭───────┬───────┬───────╮
│ x     ┆ y     ┆ z     │
│ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1     ┆ 4     ┆ 8     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 9     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     ┆ 10    │
╰───────┴───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
@DataframePublicAPI
def select(self, *columns: ColumnInputType) -> "DataFrame":
    """Creates a new DataFrame from the provided expressions, similar to a SQL ``SELECT``.

    Args:
        *columns (Union[str, Expression]): columns to select from the current DataFrame

    Returns:
        DataFrame: new DataFrame that will select the passed in columns

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> df = df.select("x", daft.col("y"), daft.col("z") + 1)
        >>> df.show()
        ╭───────┬───────┬───────╮
        │ x     ┆ y     ┆ z     │
        │ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╡
        │ 1     ┆ 4     ┆ 8     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 9     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     ┆ 10    │
        ╰───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    assert len(columns) > 0
    builder = self._builder.select(self.__column_input_to_expression(columns))
    return DataFrame(builder)

show #

show(
    n: int = 8,
    format: Optional[PreviewFormat] = None,
    verbose: bool = False,
    max_width: int = 30,
    align: PreviewAlign = "left",
    columns: Optional[List[PreviewColumn]] = None,
) -> None

Executes enough of the DataFrame in order to display the first n rows.

If IPython is installed, this will use IPython's display utility to pretty-print in a notebook/REPL environment. Otherwise, this will fall back onto a naive Python print.

If no format is given, then daft's truncating preview format is used. - The output is a 'fancy' table with rounded corners. - Headers contain the column's data type. - Columns are truncated to 30 characters. - The table's overall width is limited to 10 columns.

Parameters:

Name Type Description Default
n int

number of rows to show. Defaults to 8.

8
format PreviewFormat

the box-drawing format e.g. "fancy" or "markdown".

None
**options

keyword arguments to modify the formatting, please see the options section.

required
Options

verbose (bool) : verbose will print header info max_width (int) : global max column width align (PreviewAlign) : global column align columns (list[PreviewColumn]) : column overrides

Note

This call is blocking and will execute the DataFrame when called

Examples:

1
2
3
4
5
6
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
>>> df.show()
>>> df.show(format="markdown")
>>> df.show(max_width=50)
>>> df.show(align="left")
Usage
  • If columns are given, their length MUST match the schema.
  • If columns are given, their settings override any global settings.
Source code in daft/dataframe/dataframe.py
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
@DataframePublicAPI
def show(
    self,
    n: int = 8,
    format: Optional[PreviewFormat] = None,
    verbose: bool = False,
    max_width: int = 30,
    align: PreviewAlign = "left",
    columns: Optional[List[PreviewColumn]] = None,
) -> None:
    """Executes enough of the DataFrame in order to display the first ``n`` rows.

    If IPython is installed, this will use IPython's `display` utility to pretty-print in a
    notebook/REPL environment. Otherwise, this will fall back onto a naive Python `print`.

    If no format is given, then daft's truncating preview format is used.
        - The output is a 'fancy' table with rounded corners.
        - Headers contain the column's data type.
        - Columns are truncated to 30 characters.
        - The table's overall width is limited to 10 columns.

    Args:
        n: number of rows to show. Defaults to 8.
        format (PreviewFormat): the box-drawing format e.g. "fancy" or "markdown".
        **options: keyword arguments to modify the formatting, please see the options section.

    Options:
        verbose     (bool)                      : verbose will print header info
        max_width   (int)                       : global max column width
        align       (PreviewAlign)              : global column align
        columns     (list[PreviewColumn])       : column overrides

    Note:
        This call is **blocking** and will execute the DataFrame when called

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 8, 9]})
        >>> df.show()  # doctest: +SKIP
        >>> df.show(format="markdown")  # doctest: +SKIP
        >>> df.show(max_width=50)  # doctest: +SKIP
        >>> df.show(align="left")  # doctest: +SKIP

    Tip: Usage
        - If columns are given, their length MUST match the schema.
        - If columns are given, their settings override any global settings.

    """
    schema = self.schema()
    preview = self._construct_show_preview(n)
    preview_formatter = PreviewFormatter(
        preview,
        schema,
        format,
        **{
            "verbose": verbose,
            "max_width": max_width,
            "align": align,
            "columns": columns,
        },
    )

    try:
        from IPython.display import display

        display(preview_formatter, clear=True)
    except ImportError:
        print(preview_formatter)
    return None

sort #

sort(
    by: Union[ColumnInputType, List[ColumnInputType]],
    desc: Union[bool, List[bool]] = False,
    nulls_first: Optional[Union[bool, List[bool]]] = None,
) -> DataFrame

Sorts DataFrame globally.

Parameters:

Name Type Description Default
column Union[ColumnInputType, List[ColumnInputType]]

column to sort by. Can be str or expression as well as a list of either.

required
desc Union[bool, List[bool])

Sort by descending order. Defaults to False.

False

Returns:

Name Type Description
DataFrame DataFrame

Sorted DataFrame.

Note
  • Since this a global sort, this requires an expensive repartition which can be quite slow.
  • Supports multicolumn sorts and can have unique descending flag per column.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df = daft.from_pydict({"x": [3, 2, 1], "y": [6, 4, 5]})
>>> sorted_df = df.sort(col("x") + col("y"))
>>> sorted_df.show()
╭───────┬───────╮
│ x     ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
╰───────┴───────╯

(Showing first 3 of 3 rows)

You can also sort by multiple columns, and specify the 'descending' flag for each column:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
>>> df = daft.from_pydict({"x": [1, 2, 1, 2], "y": [9, 8, 7, 6]})
>>> sorted_df = df.sort(["x", "y"], [True, False])
>>> sorted_df.show()
╭───────┬───────╮
│ x     ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2     ┆ 6     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 8     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ 7     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ 9     │
╰───────┴───────╯

(Showing first 4 of 4 rows)

You can also specify null positioning (first/last) for each column

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
>>> df = daft.from_pydict({"x": [1, 2, 1, 2, None], "y": [9, 8, None, 6, None]})
>>> sorted_df = df.sort(["x", "y"], [True, False], nulls_first=[True, True])
>>> sorted_df.show()
╭───────┬───────╮
│ x     ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ None  ┆ None  │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 6     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 8     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ None  │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ 9     │
╰───────┴───────╯

(Showing first 5 of 5 rows)

Parameters:

Name Type Description Default
column Union[ColumnInputType, List[ColumnInputType]]

column to sort by. Can be str or expression as well as a list of either.

required
desc Union[bool, List[bool])

Sort by descending order. Defaults to False.

False
nulls_first Union[bool, List[bool])

Sort by nulls first. Defaults to nulls being treated as the greatest value.

None

Returns:

Name Type Description
DataFrame DataFrame

Sorted DataFrame.

Source code in daft/dataframe/dataframe.py
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
@DataframePublicAPI
def sort(
    self,
    by: Union[ColumnInputType, List[ColumnInputType]],
    desc: Union[bool, List[bool]] = False,
    nulls_first: Optional[Union[bool, List[bool]]] = None,
) -> "DataFrame":
    """Sorts DataFrame globally.

    Args:
        column (Union[ColumnInputType, List[ColumnInputType]]): column to sort by. Can be `str` or expression as well as a list of either.
        desc (Union[bool, List[bool]), optional): Sort by descending order. Defaults to False.

    Returns:
        DataFrame: Sorted DataFrame.

    Note:
        * Since this a global sort, this requires an expensive repartition which can be quite slow.
        * Supports multicolumn sorts and can have unique `descending` flag per column.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [3, 2, 1], "y": [6, 4, 5]})
        >>> sorted_df = df.sort(col("x") + col("y"))
        >>> sorted_df.show()
        ╭───────┬───────╮
        │ x     ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 2     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

        You can also sort by multiple columns, and specify the 'descending' flag for each column:

        >>> df = daft.from_pydict({"x": [1, 2, 1, 2], "y": [9, 8, 7, 6]})
        >>> sorted_df = df.sort(["x", "y"], [True, False])
        >>> sorted_df.show()
        ╭───────┬───────╮
        │ x     ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 2     ┆ 6     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 8     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ 7     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ 9     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)

        You can also specify null positioning (first/last) for each column

        >>> df = daft.from_pydict({"x": [1, 2, 1, 2, None], "y": [9, 8, None, 6, None]})
        >>> sorted_df = df.sort(["x", "y"], [True, False], nulls_first=[True, True])
        >>> sorted_df.show()
        ╭───────┬───────╮
        │ x     ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ None  ┆ None  │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 6     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 8     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ None  │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ 9     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 5 of 5 rows)

    Args:
        column (Union[ColumnInputType, List[ColumnInputType]]): column to sort by. Can be `str` or expression as well as a list of either.
        desc (Union[bool, List[bool]), optional): Sort by descending order. Defaults to False.
        nulls_first (Union[bool, List[bool]), optional): Sort by nulls first. Defaults to nulls being treated as the greatest value.

    Returns:
        DataFrame: Sorted DataFrame.
    """
    if not isinstance(by, list):
        by = [
            by,
        ]

    if nulls_first is None:
        nulls_first = desc

    sort_by = self.__column_input_to_expression(by)

    builder = self._builder.sort(sort_by=sort_by, descending=desc, nulls_first=nulls_first)
    return DataFrame(builder)

stddev #

stddev(*cols: ColumnInputType) -> DataFrame

Performs a global standard deviation on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to stddev

()

Returns: DataFrame: Globally aggregated standard deviation. Should be a single row.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
>>> import daft
>>> df = daft.from_pydict({"col_a": [0, 1, 2]})
>>> df = df.stddev("col_a")
>>> df.show()
╭───────────────────╮
│ col_a             │
│ ---               │
│ Float64           │
╞═══════════════════╡
│ 0.816496580927726 │
╰───────────────────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
@DataframePublicAPI
def stddev(self, *cols: ColumnInputType) -> "DataFrame":
    """Performs a global standard deviation on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to stddev
    Returns:
        DataFrame: Globally aggregated standard deviation. Should be a single row.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"col_a": [0, 1, 2]})
        >>> df = df.stddev("col_a")
        >>> df.show()
        ╭───────────────────╮
        │ col_a             │
        │ ---               │
        │ Float64           │
        ╞═══════════════════╡
        │ 0.816496580927726 │
        ╰───────────────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)

    """
    return self._apply_agg_fn(Expression.stddev, cols)

sum #

sum(*cols: ManyColumnsInputType) -> DataFrame

Performs a global sum on the DataFrame.

Parameters:

Name Type Description Default
*cols Union[str, Expression]

columns to sum

()

Returns: DataFrame: Globally aggregated sums. Should be a single row.

Source code in daft/dataframe/dataframe.py
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
@DataframePublicAPI
def sum(self, *cols: ManyColumnsInputType) -> "DataFrame":
    """Performs a global sum on the DataFrame.

    Args:
        *cols (Union[str, Expression]): columns to sum
    Returns:
        DataFrame: Globally aggregated sums. Should be a single row.
    """
    return self._apply_agg_fn(Expression.sum, cols)

summarize #

summarize() -> DataFrame

Returns column statistics for the DataFrame.

Returns:

Name Type Description
DataFrame DataFrame

new DataFrame with the computed column statistics.

Source code in daft/dataframe/dataframe.py
1427
1428
1429
1430
1431
1432
1433
1434
1435
@DataframePublicAPI
def summarize(self) -> "DataFrame":
    """Returns column statistics for the DataFrame.

    Returns:
        DataFrame: new DataFrame with the computed column statistics.
    """
    builder = self._builder.summarize()
    return DataFrame(builder)

to_arrow #

to_arrow() -> Table

Converts the current DataFrame to a pyarrow Table.

If results have not computed yet, collect will be called.

Returns:

Type Description
Table

pyarrow.Table: pyarrow Table converted from a Daft DataFrame

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
@DataframePublicAPI
def to_arrow(self) -> "pyarrow.Table":
    """Converts the current DataFrame to a [pyarrow Table](https://arrow.apache.org/docs/python/generated/pyarrow.Table.html).

    If results have not computed yet, collect will be called.

    Returns:
        pyarrow.Table: [pyarrow Table](https://arrow.apache.org/docs/python/generated/pyarrow.Table.html) converted from a Daft DataFrame

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    import pyarrow as pa

    arrow_rb_iter = self.to_arrow_iter(results_buffer_size=None)
    return pa.Table.from_batches(arrow_rb_iter, schema=self.schema().to_pyarrow_schema())

to_arrow_iter #

to_arrow_iter(
    results_buffer_size: Union[
        Optional[int], Literal["num_cpus"]
    ] = "num_cpus",
) -> Iterator[RecordBatch]

Return an iterator of pyarrow recordbatches for this dataframe.

Source code in daft/dataframe/dataframe.py
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
@DataframePublicAPI
def to_arrow_iter(
    self,
    results_buffer_size: Union[Optional[int], Literal["num_cpus"]] = "num_cpus",
) -> Iterator["pyarrow.RecordBatch"]:
    """Return an iterator of pyarrow recordbatches for this dataframe."""
    for name in self.schema().column_names():
        if self.schema()[name].dtype.is_python():
            raise ValueError(
                f"Cannot convert column {name} to Arrow type, found Python type: {self.schema()[name].dtype}"
            )

    if results_buffer_size == "num_cpus":
        results_buffer_size = multiprocessing.cpu_count()
    if results_buffer_size is not None and not results_buffer_size > 0:
        raise ValueError(f"Provided `results_buffer_size` value must be > 0, received: {results_buffer_size}")
    if self._result is not None:
        # If the dataframe has already finished executing,
        # use the precomputed results.
        for _, result in self._result.items():
            yield from (result.micropartition().to_arrow().to_batches())
    else:
        # Execute the dataframe in a streaming fashion.
        context = get_context()
        partitions_iter = context.get_or_create_runner().run_iter_tables(
            self._builder, results_buffer_size=results_buffer_size
        )

        # Iterate through partitions.
        for partition in partitions_iter:
            yield from partition.to_arrow().to_batches()

to_dask_dataframe #

to_dask_dataframe(
    meta: Union[
        DataFrame,
        Series,
        Dict[str, Any],
        Iterable[Any],
        Tuple[Any],
        None,
    ] = None,
) -> DataFrame

Converts the current Daft DataFrame to a Dask DataFrame.

The returned Dask DataFrame will use Dask-on-Ray to execute operations on a Ray cluster.

Parameters:

Name Type Description Default
meta Union[DataFrame, Series, Dict[str, Any], Iterable[Any], Tuple[Any], None]

An empty pandas DataFrameor Series that matches the dtypes and column names of the stream. This metadata is necessary for many algorithms in dask dataframe to work. For ease of use, some alternative inputs are also available. Instead of a DataFrame, a dict of {name: dtype} or iterable of (name, dtype) can be provided (note that the order of the names should match the order of the columns). Instead of a series, a tuple of (name, dtype) can be used. By default, this will be inferred from the underlying Daft DataFrame schema, with this argument supplying an optional override.

None

Returns:

Type Description
DataFrame

dask.DataFrame: A Dask DataFrame stored on a Ray cluster.

Note

This function can only work if Daft is running using the RayRunner.

Source code in daft/dataframe/dataframe.py
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
@DataframePublicAPI
def to_dask_dataframe(
    self,
    meta: Union[
        "pandas.DataFrame",
        "pandas.Series",
        Dict[str, Any],
        Iterable[Any],
        Tuple[Any],
        None,
    ] = None,
) -> "dask.DataFrame":
    """Converts the current Daft DataFrame to a Dask DataFrame.

    The returned Dask DataFrame will use [Dask-on-Ray](https://docs.ray.io/en/latest/ray-more-libs/dask-on-ray.html)
    to execute operations on a Ray cluster.

    Args:
        meta: An empty [pandas DataFrame](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.html)or [Series](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.html) that matches the dtypes and column
            names of the stream. This metadata is necessary for many algorithms in
            dask dataframe to work. For ease of use, some alternative inputs are
            also available. Instead of a DataFrame, a dict of ``{name: dtype}`` or
            iterable of ``(name, dtype)`` can be provided (note that the order of
            the names should match the order of the columns). Instead of a series, a
            tuple of ``(name, dtype)`` can be used.
            By default, this will be inferred from the underlying Daft DataFrame schema,
            with this argument supplying an optional override.

    Returns:
        dask.DataFrame: A Dask DataFrame stored on a Ray cluster.

    Note:
        This function can only work if Daft is running using the RayRunner.

    """
    from daft.runners.ray_runner import RayPartitionSet

    self.collect()
    partition_set = self._result
    assert partition_set is not None
    # TODO(Clark): Support Dask DataFrame conversion for the local runner if
    # Dask is using a non-distributed scheduler.
    if not isinstance(partition_set, RayPartitionSet):
        raise ValueError("Cannot convert to Dask DataFrame if not running on Ray backend")
    return partition_set.to_dask_dataframe(meta)

to_pandas #

to_pandas(
    coerce_temporal_nanoseconds: bool = False,
) -> DataFrame

Converts the current DataFrame to a pandas DataFrame.

If results have not computed yet, collect will be called.

Parameters:

Name Type Description Default
coerce_temporal_nanoseconds bool

Whether to coerce temporal columns to nanoseconds. Only applicable to pandas version >= 2.0 and pyarrow version >= 13.0.0. Defaults to False. See pyarrow.Table.to_pandas <https://arrow.apache.org/docs/python/generated/pyarrow.Table.html#pyarrow.Table.to_pandas>__ for more information.

False

Returns:

Type Description
DataFrame

pandas.DataFrame: pandas DataFrame converted from a Daft DataFrame

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
@DataframePublicAPI
def to_pandas(self, coerce_temporal_nanoseconds: bool = False) -> "pandas.DataFrame":
    """Converts the current DataFrame to a [pandas DataFrame](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.html).

    If results have not computed yet, collect will be called.

    Args:
        coerce_temporal_nanoseconds (bool): Whether to coerce temporal columns to nanoseconds. Only applicable to pandas version >= 2.0 and pyarrow version >= 13.0.0. Defaults to False. See `pyarrow.Table.to_pandas <https://arrow.apache.org/docs/python/generated/pyarrow.Table.html#pyarrow.Table.to_pandas>`__ for more information.

    Returns:
        pandas.DataFrame: [pandas DataFrame](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.html) converted from a Daft DataFrame

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    self.collect()
    result = self._result
    assert result is not None

    pd_df = result.to_pandas(
        schema=self._builder.schema(),
        coerce_temporal_nanoseconds=coerce_temporal_nanoseconds,
    )
    return pd_df

to_pydict #

to_pydict() -> Dict[str, List[Any]]

Converts the current DataFrame to a python dictionary. The dictionary contains Python lists of Python objects for each column.

If results have not computed yet, collect will be called.

Returns:

Type Description
Dict[str, List[Any]]

dict[str, list[Any]]: python dict converted from a Daft DataFrame

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
@DataframePublicAPI
def to_pydict(self) -> Dict[str, List[Any]]:
    """Converts the current DataFrame to a python dictionary. The dictionary contains Python lists of Python objects for each column.

    If results have not computed yet, collect will be called.

    Returns:
        dict[str, list[Any]]: python dict converted from a Daft DataFrame

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    self.collect()
    result = self._result
    assert result is not None
    return result.to_pydict()

to_pylist #

to_pylist() -> List[Any]

Converts the current Dataframe into a python list.

Returns:

Type Description
List[Any]

List[dict[str, Any]]: List of python dict objects.

Warning

This is a convenience method over DataFrame.iter_rows(). Users should prefer using .iter_rows() directly instead for lower memory utilization if they are streaming rows out of a DataFrame and don't require full materialization of the Python list.

Examples:

1
2
3
4
5
>>> import daft
>>> from daft import col
>>> df = daft.from_pydict({"a": [1, 2, 3, 4], "b": [2, 4, 3, 1]})
>>> print(df.to_pylist())
[{'a': 1, 'b': 2}, {'a': 2, 'b': 4}, {'a': 3, 'b': 3}, {'a': 4, 'b': 1}]
See also

df.iter_rows(): streaming iterator over individual rows in a DataFrame

Source code in daft/dataframe/dataframe.py
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
@DataframePublicAPI
def to_pylist(self) -> List[Any]:
    """Converts the current Dataframe into a python list.

    Returns:
        List[dict[str, Any]]: List of python dict objects.

    Warning:
        This is a convenience method over [DataFrame.iter_rows()][daft.DataFrame.iter_rows]. Users should prefer using `.iter_rows()` directly instead for lower memory utilization if they are streaming rows out of a DataFrame and don't require full materialization of the Python list.

    Examples:
        >>> import daft
        >>> from daft import col
        >>> df = daft.from_pydict({"a": [1, 2, 3, 4], "b": [2, 4, 3, 1]})
        >>> print(df.to_pylist())
        [{'a': 1, 'b': 2}, {'a': 2, 'b': 4}, {'a': 3, 'b': 3}, {'a': 4, 'b': 1}]

    Tip: See also
        [df.iter_rows()][daft.DataFrame.iter_rows]: streaming iterator over individual rows in a DataFrame
    """
    return list(self.iter_rows())

to_ray_dataset #

to_ray_dataset() -> DataSet

Converts the current DataFrame to a Ray Dataset which is useful for running distributed ML model training in Ray.

Returns:

Type Description
DataSet

ray.data.dataset.DataSet: Ray dataset

Note

This function can only work if Daft is running using the RayRunner

Source code in daft/dataframe/dataframe.py
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
@DataframePublicAPI
def to_ray_dataset(self) -> "ray.data.dataset.DataSet":
    """Converts the current DataFrame to a [Ray Dataset](https://docs.ray.io/en/latest/data/api/dataset.html#ray.data.Dataset) which is useful for running distributed ML model training in Ray.

    Returns:
        ray.data.dataset.DataSet: [Ray dataset](https://docs.ray.io/en/latest/data/api/dataset.html#ray.data.Dataset)

    Note:
        This function can only work if Daft is running using the RayRunner
    """
    from daft.runners.ray_runner import RayPartitionSet

    self.collect()
    partition_set = self._result
    assert partition_set is not None
    if not isinstance(partition_set, RayPartitionSet):
        raise ValueError("Cannot convert to Ray Dataset if not running on Ray backend")
    return partition_set.to_ray_dataset()

to_torch_iter_dataset #

to_torch_iter_dataset() -> IterableDataset

Convert the current DataFrame into a Torch IterableDataset <https://pytorch.org/docs/stable/data.html#torch.utils.data.IterableDataset>__ for use with PyTorch.

Begins execution of the DataFrame if it is not yet executed.

Items will be returned in pydict format: a dict of {"column name": value} for each row in the data.

Note

The produced dataset is meant to be used with the single-process DataLoader, and does not support data sharding hooks for multi-process data loading.

Do keep in mind that Daft is already using multithreading or multiprocessing under the hood to compute the data stream that feeds this dataset.

Tip

This method returns results locally. For distributed training, you may want to use DataFrame.to_ray_dataset().

Source code in daft/dataframe/dataframe.py
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
@DataframePublicAPI
def to_torch_iter_dataset(self) -> "torch.utils.data.IterableDataset":
    """Convert the current DataFrame into a `Torch IterableDataset <https://pytorch.org/docs/stable/data.html#torch.utils.data.IterableDataset>`__ for use with PyTorch.

    Begins execution of the DataFrame if it is not yet executed.

    Items will be returned in pydict format: a dict of `{"column name": value}` for each row in the data.

    Note:
        The produced dataset is meant to be used with the single-process DataLoader,
        and does not support data sharding hooks for multi-process data loading.

        Do keep in mind that Daft is already using multithreading or multiprocessing under the hood
        to compute the data stream that feeds this dataset.

    Tip:
        This method returns results locally.
        For distributed training, you may want to use [DataFrame.to_ray_dataset()][daft.DataFrame.to_ray_dataset].
    """
    from daft.dataframe.to_torch import DaftTorchIterableDataset

    return DaftTorchIterableDataset(self)

to_torch_map_dataset #

to_torch_map_dataset() -> Dataset

Convert the current DataFrame into a map-style Torch Dataset for use with PyTorch.

This method will materialize the entire DataFrame and block on completion.

Items will be returned in pydict format: a dict of {"column name": value} for each row in the data.

Note

If you do not need random access, you may get better performance out of an IterableDataset, which streams data items in as soon as they are ready and does not block on full materialization.

Tip

This method returns results locally. For distributed training, you may want to use DataFrame.to_ray_dataset().

Source code in daft/dataframe/dataframe.py
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
@DataframePublicAPI
def to_torch_map_dataset(self) -> "torch.utils.data.Dataset":
    """Convert the current DataFrame into a map-style [Torch Dataset](https://pytorch.org/docs/stable/data.html#map-style-datasets) for use with PyTorch.

    This method will materialize the entire DataFrame and block on completion.

    Items will be returned in pydict format: a dict of `{"column name": value}` for each row in the data.

    Note:
        If you do not need random access, you may get better performance out of an IterableDataset,
        which streams data items in as soon as they are ready and does not block on full materialization.

    Tip:
        This method returns results locally.
        For distributed training, you may want to use [DataFrame.to_ray_dataset()][daft.DataFrame.to_ray_dataset].
    """
    from daft.dataframe.to_torch import DaftTorchDataset

    return DaftTorchDataset(self.to_pydict(), len(self))

transform #

transform(
    func: Callable[..., DataFrame],
    *args: Any,
    **kwargs: Any,
) -> DataFrame

Apply a function that takes and returns a DataFrame.

Allow splitting your transformation into different units of work (functions) while preserving the syntax for chaining transformations.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
>>> import daft
>>> df = daft.from_pydict({"col_a": [1, 2, 3, 4]})
>>> def add_1(df):
...     df = df.select(daft.col("col_a") + 1)
...     return df
>>> def multiply_x(df, x):
...     df = df.select(daft.col("col_a") * x)
...     return df
>>> df = df.transform(add_1).transform(multiply_x, 4)
>>> df.show()
╭───────╮
│ col_a │
│ ---   │
│ Int64 │
╞═══════╡
│ 8     │
├╌╌╌╌╌╌╌┤
│ 12    │
├╌╌╌╌╌╌╌┤
│ 16    │
├╌╌╌╌╌╌╌┤
│ 20    │
╰───────╯

(Showing first 4 of 4 rows)

Parameters:

Name Type Description Default
func Callable[..., DataFrame]

A function that takes and returns a DataFrame.

required
*args Any

Positional arguments to pass to func.

()
**kwargs Any

Keyword arguments to pass to func.

{}

Returns:

Name Type Description
DataFrame DataFrame

Transformed DataFrame.

Source code in daft/dataframe/dataframe.py
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
@DataframePublicAPI
def transform(self, func: Callable[..., "DataFrame"], *args: Any, **kwargs: Any) -> "DataFrame":
    """Apply a function that takes and returns a DataFrame.

    Allow splitting your transformation into different units of work (functions) while preserving the syntax for chaining transformations.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"col_a": [1, 2, 3, 4]})
        >>> def add_1(df):
        ...     df = df.select(daft.col("col_a") + 1)
        ...     return df
        >>> def multiply_x(df, x):
        ...     df = df.select(daft.col("col_a") * x)
        ...     return df
        >>> df = df.transform(add_1).transform(multiply_x, 4)
        >>> df.show()
        ╭───────╮
        │ col_a │
        │ ---   │
        │ Int64 │
        ╞═══════╡
        │ 8     │
        ├╌╌╌╌╌╌╌┤
        │ 12    │
        ├╌╌╌╌╌╌╌┤
        │ 16    │
        ├╌╌╌╌╌╌╌┤
        │ 20    │
        ╰───────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)

    Args:
        func: A function that takes and returns a DataFrame.
        *args: Positional arguments to pass to func.
        **kwargs: Keyword arguments to pass to func.

    Returns:
        DataFrame: Transformed DataFrame.
    """
    result = func(self, *args, **kwargs)
    assert isinstance(
        result, DataFrame
    ), f"Func returned an instance of type [{type(result)}], should have been DataFrame."
    return result

union #

union(other: DataFrame) -> DataFrame

Returns the distinct union of two DataFrames.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
>>> import daft
>>> df1 = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
>>> df2 = daft.from_pydict({"x": [3, 4, 5], "y": [6, 7, 8]})
>>> df1.union(df2).sort("x").show()
╭───────┬───────╮
│ x     ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 4     ┆ 7     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 5     ┆ 8     │
╰───────┴───────╯

(Showing first 5 of 5 rows)
Source code in daft/dataframe/dataframe.py
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
@DataframePublicAPI
def union(self, other: "DataFrame") -> "DataFrame":
    """Returns the distinct union of two DataFrames.

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
        >>> df2 = daft.from_pydict({"x": [3, 4, 5], "y": [6, 7, 8]})
        >>> df1.union(df2).sort("x").show()
        ╭───────┬───────╮
        │ x     ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 4     ┆ 7     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 5     ┆ 8     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 5 of 5 rows)
    """
    builder = self._builder.union(other._builder)
    return DataFrame(builder)

union_all #

union_all(other: DataFrame) -> DataFrame

Returns the union of two DataFrames, including duplicates.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
>>> import daft
>>> df1 = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
>>> df2 = daft.from_pydict({"x": [3, 2, 1], "y": [6, 5, 4]})
>>> df1.union_all(df2).sort("x").show()
╭───────┬───────╮
│ x     ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
╰───────┴───────╯

(Showing first 6 of 6 rows)
Source code in daft/dataframe/dataframe.py
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
@DataframePublicAPI
def union_all(self, other: "DataFrame") -> "DataFrame":
    """Returns the union of two DataFrames, including duplicates.

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
        >>> df2 = daft.from_pydict({"x": [3, 2, 1], "y": [6, 5, 4]})
        >>> df1.union_all(df2).sort("x").show()
        ╭───────┬───────╮
        │ x     ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 6 of 6 rows)
    """
    builder = self._builder.union(other._builder, is_all=True)
    return DataFrame(builder)

union_all_by_name #

union_all_by_name(other: DataFrame) -> DataFrame

Returns the union of two DataFrames, including duplicates, with columns matched by name.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
>>> import daft
>>> df1 = daft.from_pydict({"x": [1, 2], "y": [4, 5], "w": [9, 10]})
>>> df2 = daft.from_pydict({"y": [6, 6, 7, 7], "z": ["a", "a", "b", "b"]})
>>> df1.union_all_by_name(df2).sort("y").show()
╭───────┬───────┬───────┬──────╮
│ x     ┆ y     ┆ w     ┆ z    │
│ ---   ┆ ---   ┆ ---   ┆ ---  │
│ Int64 ┆ Int64 ┆ Int64 ┆ Utf8 │
╞═══════╪═══════╪═══════╪══════╡
│ 1     ┆ 4     ┆ 9     ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 10    ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 6     ┆ None  ┆ a    │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 6     ┆ None  ┆ a    │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 7     ┆ None  ┆ b    │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 7     ┆ None  ┆ b    │
╰───────┴───────┴───────┴──────╯

(Showing first 6 of 6 rows)
Source code in daft/dataframe/dataframe.py
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
@DataframePublicAPI
def union_all_by_name(self, other: "DataFrame") -> "DataFrame":
    """Returns the union of two DataFrames, including duplicates, with columns matched by name.

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"x": [1, 2], "y": [4, 5], "w": [9, 10]})
        >>> df2 = daft.from_pydict({"y": [6, 6, 7, 7], "z": ["a", "a", "b", "b"]})
        >>> df1.union_all_by_name(df2).sort("y").show()
        ╭───────┬───────┬───────┬──────╮
        │ x     ┆ y     ┆ w     ┆ z    │
        │ ---   ┆ ---   ┆ ---   ┆ ---  │
        │ Int64 ┆ Int64 ┆ Int64 ┆ Utf8 │
        ╞═══════╪═══════╪═══════╪══════╡
        │ 1     ┆ 4     ┆ 9     ┆ None │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 10    ┆ None │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 6     ┆ None  ┆ a    │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 6     ┆ None  ┆ a    │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 7     ┆ None  ┆ b    │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 7     ┆ None  ┆ b    │
        ╰───────┴───────┴───────┴──────╯
        <BLANKLINE>
        (Showing first 6 of 6 rows)
    """
    builder = self._builder.union(other._builder, is_all=True, is_by_name=True)
    return DataFrame(builder)

union_by_name #

union_by_name(other: DataFrame) -> DataFrame

Returns the distinct union by name.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
>>> import daft
>>> df1 = daft.from_pydict({"x": [1, 2], "y": [4, 5], "w": [9, 10]})
>>> df2 = daft.from_pydict({"y": [6, 7], "z": ["a", "b"]})
>>> df1.union_by_name(df2).sort("y").show()
╭───────┬───────┬───────┬──────╮
│ x     ┆ y     ┆ w     ┆ z    │
│ ---   ┆ ---   ┆ ---   ┆ ---  │
│ Int64 ┆ Int64 ┆ Int64 ┆ Utf8 │
╞═══════╪═══════╪═══════╪══════╡
│ 1     ┆ 4     ┆ 9     ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 10    ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 6     ┆ None  ┆ a    │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
│ None  ┆ 7     ┆ None  ┆ b    │
╰───────┴───────┴───────┴──────╯

(Showing first 4 of 4 rows)
Source code in daft/dataframe/dataframe.py
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
@DataframePublicAPI
def union_by_name(self, other: "DataFrame") -> "DataFrame":
    """Returns the distinct union by name.

    Examples:
        >>> import daft
        >>> df1 = daft.from_pydict({"x": [1, 2], "y": [4, 5], "w": [9, 10]})
        >>> df2 = daft.from_pydict({"y": [6, 7], "z": ["a", "b"]})
        >>> df1.union_by_name(df2).sort("y").show()
        ╭───────┬───────┬───────┬──────╮
        │ x     ┆ y     ┆ w     ┆ z    │
        │ ---   ┆ ---   ┆ ---   ┆ ---  │
        │ Int64 ┆ Int64 ┆ Int64 ┆ Utf8 │
        ╞═══════╪═══════╪═══════╪══════╡
        │ 1     ┆ 4     ┆ 9     ┆ None │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 10    ┆ None │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 6     ┆ None  ┆ a    │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌┤
        │ None  ┆ 7     ┆ None  ┆ b    │
        ╰───────┴───────┴───────┴──────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)
    """
    builder = self._builder.union(other._builder, is_all=False, is_by_name=True)
    return DataFrame(builder)

unique #

unique() -> DataFrame

Computes distinct rows, dropping duplicates.

Alias for DataFrame.distinct.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 2], "y": [4, 5, 5], "z": [7, 8, 8]})
>>> distinct_df = df.unique()
>>> distinct_df = distinct_df.sort("x")
>>> distinct_df.show()
╭───────┬───────┬───────╮
│ x     ┆ y     ┆ z     │
│ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1     ┆ 4     ┆ 7     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 8     │
╰───────┴───────┴───────╯

(Showing first 2 of 2 rows)

Returns:

Name Type Description
DataFrame DataFrame

DataFrame that has only distinct rows.

Source code in daft/dataframe/dataframe.py
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
@DataframePublicAPI
def unique(self) -> "DataFrame":
    """Computes distinct rows, dropping duplicates.

    Alias for [DataFrame.distinct][daft.DataFrame.distinct].

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 2], "y": [4, 5, 5], "z": [7, 8, 8]})
        >>> distinct_df = df.unique()
        >>> distinct_df = distinct_df.sort("x")
        >>> distinct_df.show()
        ╭───────┬───────┬───────╮
        │ x     ┆ y     ┆ z     │
        │ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╡
        │ 1     ┆ 4     ┆ 7     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 8     │
        ╰───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

    Returns:
        DataFrame: DataFrame that has only distinct rows.
    """
    return self.distinct()

unpivot #

unpivot(
    ids: ManyColumnsInputType,
    values: ManyColumnsInputType = [],
    variable_name: str = "variable",
    value_name: str = "value",
) -> DataFrame

Unpivots a DataFrame from wide to long format.

Parameters:

Name Type Description Default
ids ManyColumnsInputType

Columns to keep as identifiers

required
values Optional[ManyColumnsInputType]

Columns to unpivot. If not specified, all columns except ids will be unpivoted.

[]
variable_name Optional[str]

Name of the variable column. Defaults to "variable".

'variable'
value_name Optional[str]

Name of the value column. Defaults to "value".

'value'

Returns:

Name Type Description
DataFrame DataFrame

Unpivoted DataFrame

Tip

See also melt

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
>>> import daft
>>> df = daft.from_pydict(
...     {
...         "year": [2020, 2021, 2022],
...         "Jan": [10, 30, 50],
...         "Feb": [20, 40, 60],
...     }
... )
>>> df = df.unpivot("year", ["Jan", "Feb"], variable_name="month", value_name="inventory")
>>> df = df.sort("year")
>>> df.show()
╭───────┬───────┬───────────╮
│ year  ┆ month ┆ inventory │
│ ---   ┆ ---   ┆ ---       │
│ Int64 ┆ Utf8  ┆ Int64     │
╞═══════╪═══════╪═══════════╡
│ 2020  ┆ Jan   ┆ 10        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2020  ┆ Feb   ┆ 20        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021  ┆ Jan   ┆ 30        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021  ┆ Feb   ┆ 40        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022  ┆ Jan   ┆ 50        │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022  ┆ Feb   ┆ 60        │
╰───────┴───────┴───────────╯

(Showing first 6 of 6 rows)
Source code in daft/dataframe/dataframe.py
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
@DataframePublicAPI
def unpivot(
    self,
    ids: ManyColumnsInputType,
    values: ManyColumnsInputType = [],
    variable_name: str = "variable",
    value_name: str = "value",
) -> "DataFrame":
    """Unpivots a DataFrame from wide to long format.

    Args:
        ids (ManyColumnsInputType): Columns to keep as identifiers
        values (Optional[ManyColumnsInputType]): Columns to unpivot. If not specified, all columns except ids will be unpivoted.
        variable_name (Optional[str]): Name of the variable column. Defaults to "variable".
        value_name (Optional[str]): Name of the value column. Defaults to "value".

    Returns:
        DataFrame: Unpivoted DataFrame

    Tip:
        See also [melt][daft.DataFrame.melt]

    Examples:
        >>> import daft
        >>> df = daft.from_pydict(
        ...     {
        ...         "year": [2020, 2021, 2022],
        ...         "Jan": [10, 30, 50],
        ...         "Feb": [20, 40, 60],
        ...     }
        ... )
        >>> df = df.unpivot("year", ["Jan", "Feb"], variable_name="month", value_name="inventory")
        >>> df = df.sort("year")
        >>> df.show()
        ╭───────┬───────┬───────────╮
        │ year  ┆ month ┆ inventory │
        │ ---   ┆ ---   ┆ ---       │
        │ Int64 ┆ Utf8  ┆ Int64     │
        ╞═══════╪═══════╪═══════════╡
        │ 2020  ┆ Jan   ┆ 10        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2020  ┆ Feb   ┆ 20        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2021  ┆ Jan   ┆ 30        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2021  ┆ Feb   ┆ 40        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2022  ┆ Jan   ┆ 50        │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
        │ 2022  ┆ Feb   ┆ 60        │
        ╰───────┴───────┴───────────╯
        <BLANKLINE>
        (Showing first 6 of 6 rows)

    """
    ids_exprs = column_inputs_to_expressions(ids)
    values_exprs = column_inputs_to_expressions(values)

    builder = self._builder.unpivot(ids_exprs, values_exprs, variable_name, value_name)
    return DataFrame(builder)

where #

where(predicate: Union[Expression, str]) -> DataFrame

Filters rows via a predicate expression, similar to SQL WHERE.

Parameters:

Name Type Description Default
predicate Expression

expression that keeps row if evaluates to True.

required

Returns:

Name Type Description
DataFrame DataFrame

Filtered DataFrame.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 6, 6], "z": [7, 8, 9]})
>>> df.where((col("x") > 1) & (col("y") > 1)).collect()
╭───────┬───────┬───────╮
│ x     ┆ y     ┆ z     │
│ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 2     ┆ 6     ┆ 8     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     ┆ 9     │
╰───────┴───────┴───────╯

(Showing first 2 of 2 rows)

You can also use a string expression as a predicate.

Note: this will use the method sql_expr to parse the string into an expression this may raise an error if the expression is not yet supported in the sql engine.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 9, 9]})
>>> df.where("z = 9 AND y > 5").collect()
╭───────┬───────┬───────╮
│ x     ┆ y     ┆ z     │
│ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 3     ┆ 6     ┆ 9     │
╰───────┴───────┴───────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
@DataframePublicAPI
def where(self, predicate: Union[Expression, str]) -> "DataFrame":
    """Filters rows via a predicate expression, similar to SQL ``WHERE``.

    Args:
        predicate (Expression): expression that keeps row if evaluates to True.

    Returns:
        DataFrame: Filtered DataFrame.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 6, 6], "z": [7, 8, 9]})
        >>> df.where((col("x") > 1) & (col("y") > 1)).collect()
        ╭───────┬───────┬───────╮
        │ x     ┆ y     ┆ z     │
        │ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╡
        │ 2     ┆ 6     ┆ 8     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     ┆ 9     │
        ╰───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)

        You can also use a string expression as a predicate.

        Note: this will use the method `sql_expr` to parse the string into an expression
        this may raise an error if the expression is not yet supported in the sql engine.

        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6], "z": [7, 9, 9]})
        >>> df.where("z = 9 AND y > 5").collect()
        ╭───────┬───────┬───────╮
        │ x     ┆ y     ┆ z     │
        │ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╡
        │ 3     ┆ 6     ┆ 9     │
        ╰───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)
    """
    if isinstance(predicate, str):
        from daft.sql.sql import sql_expr

        predicate = sql_expr(predicate)
    builder = self._builder.filter(predicate)
    return DataFrame(builder)

with_column #

with_column(
    column_name: str, expr: Expression
) -> DataFrame

Adds a column to the current DataFrame with an Expression, equivalent to a select with all current columns and the new one.

Parameters:

Name Type Description Default
column_name str

name of new column

required
expr Expression

expression of the new column.

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with new column.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3]})
>>> new_df = df.with_column("x+1", col("x") + 1)
>>> new_df.show()
╭───────┬───────╮
│ x     ┆ x+1   │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 2     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 3     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 4     │
╰───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
@DataframePublicAPI
def with_column(
    self,
    column_name: str,
    expr: Expression,
) -> "DataFrame":
    """Adds a column to the current DataFrame with an Expression, equivalent to a ``select`` with all current columns and the new one.

    Args:
        column_name (str): name of new column
        expr (Expression): expression of the new column.

    Returns:
        DataFrame: DataFrame with new column.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3]})
        >>> new_df = df.with_column("x+1", col("x") + 1)
        >>> new_df.show()
        ╭───────┬───────╮
        │ x     ┆ x+1   │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 2     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 3     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 4     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    return self.with_columns({column_name: expr})

with_column_renamed #

with_column_renamed(existing: str, new: str) -> DataFrame

Renames a column in the current DataFrame.

If the column in the DataFrame schema does not exist, this will be a no-op.

Parameters:

Name Type Description Default
existing str

name of the existing column to rename

required
new str

new name for the column

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the column renamed.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
>>> df.with_column_renamed("x", "foo").show()
╭───────┬───────╮
│ foo   ┆ y     │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
╰───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
@DataframePublicAPI
def with_column_renamed(self, existing: str, new: str) -> "DataFrame":
    """Renames a column in the current DataFrame.

    If the column in the DataFrame schema does not exist, this will be a no-op.

    Args:
        existing (str): name of the existing column to rename
        new (str): new name for the column

    Returns:
        DataFrame: DataFrame with the column renamed.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
        >>> df.with_column_renamed("x", "foo").show()
        ╭───────┬───────╮
        │ foo   ┆ y     │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    builder = self._builder.with_column_renamed(existing, new)
    return DataFrame(builder)

with_columns #

with_columns(columns: Dict[str, Expression]) -> DataFrame

Adds columns to the current DataFrame with Expressions, equivalent to a select with all current columns and the new ones.

Parameters:

Name Type Description Default
columns Dict[str, Expression]

Dictionary of new columns in the format { name: expression }

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with new columns.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
>>> new_df = df.with_columns({"foo": df["x"] + 1, "bar": df["y"] - df["x"]})
>>> new_df.show()
╭───────┬───────┬───────┬───────╮
│ x     ┆ y     ┆ foo   ┆ bar   │
│ ---   ┆ ---   ┆ ---   ┆ ---   │
│ Int64 ┆ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╪═══════╡
│ 1     ┆ 4     ┆ 2     ┆ 3     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     ┆ 3     ┆ 3     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     ┆ 4     ┆ 3     │
╰───────┴───────┴───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
@DataframePublicAPI
def with_columns(
    self,
    columns: Dict[str, Expression],
) -> "DataFrame":
    """Adds columns to the current DataFrame with Expressions, equivalent to a ``select`` with all current columns and the new ones.

    Args:
        columns (Dict[str, Expression]): Dictionary of new columns in the format { name: expression }

    Returns:
        DataFrame: DataFrame with new columns.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
        >>> new_df = df.with_columns({"foo": df["x"] + 1, "bar": df["y"] - df["x"]})
        >>> new_df.show()
        ╭───────┬───────┬───────┬───────╮
        │ x     ┆ y     ┆ foo   ┆ bar   │
        │ ---   ┆ ---   ┆ ---   ┆ ---   │
        │ Int64 ┆ Int64 ┆ Int64 ┆ Int64 │
        ╞═══════╪═══════╪═══════╪═══════╡
        │ 1     ┆ 4     ┆ 2     ┆ 3     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     ┆ 3     ┆ 3     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     ┆ 4     ┆ 3     │
        ╰───────┴───────┴───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    new_columns = [col.alias(name) for name, col in columns.items()]

    builder = self._builder.with_columns(new_columns)
    return DataFrame(builder)

with_columns_renamed #

with_columns_renamed(cols_map: Dict[str, str]) -> DataFrame

Renames multiple columns in the current DataFrame.

If the columns in the DataFrame schema do not exist, this will be a no-op.

Parameters:

Name Type Description Default
cols_map Dict[str, str]

Dictionary of columns to rename in the format { existing: new }

required

Returns:

Name Type Description
DataFrame DataFrame

DataFrame with the columns renamed.

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
>>> import daft
>>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
>>> df.with_columns_renamed({"x": "foo", "y": "bar"}).show()
╭───────┬───────╮
│ foo   ┆ bar   │
│ ---   ┆ ---   │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1     ┆ 4     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2     ┆ 5     │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3     ┆ 6     │
╰───────┴───────╯

(Showing first 3 of 3 rows)
Source code in daft/dataframe/dataframe.py
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
@DataframePublicAPI
def with_columns_renamed(self, cols_map: Dict[str, str]) -> "DataFrame":
    """Renames multiple columns in the current DataFrame.

    If the columns in the DataFrame schema do not exist, this will be a no-op.

    Args:
        cols_map (Dict[str, str]): Dictionary of columns to rename in the format { existing: new }

    Returns:
        DataFrame: DataFrame with the columns renamed.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"x": [1, 2, 3], "y": [4, 5, 6]})
        >>> df.with_columns_renamed({"x": "foo", "y": "bar"}).show()
        ╭───────┬───────╮
        │ foo   ┆ bar   │
        │ ---   ┆ ---   │
        │ Int64 ┆ Int64 │
        ╞═══════╪═══════╡
        │ 1     ┆ 4     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 2     ┆ 5     │
        ├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ 3     ┆ 6     │
        ╰───────┴───────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)
    """
    builder = self._builder.with_columns_renamed(cols_map)
    return DataFrame(builder)

write_csv #

write_csv(
    root_dir: Union[str, Path],
    write_mode: Literal[
        "append", "overwrite", "overwrite-partitions"
    ] = "append",
    partition_cols: Optional[List[ColumnInputType]] = None,
    io_config: Optional[IOConfig] = None,
) -> DataFrame

Writes the DataFrame as CSV files, returning a new DataFrame with paths to the files that were written.

Files will be written to <root_dir>/* with randomly generated UUIDs as the file names.

Parameters:

Name Type Description Default
root_dir str

root file path to write parquet files to.

required
write_mode str

Operation mode of the write. append will add new data, overwrite will replace the contents of the root directory with new data. overwrite-partitions will replace only the contents in the partitions that are being written to. Defaults to "append".

'append'
partition_cols Optional[List[ColumnInputType]]

How to subpartition each partition further. Defaults to None.

None
io_config Optional[IOConfig]

configurations to use when interacting with remote storage.

None

Returns:

Name Type Description
DataFrame DataFrame

The filenames that were written out as strings.

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
@DataframePublicAPI
def write_csv(
    self,
    root_dir: Union[str, pathlib.Path],
    write_mode: Literal["append", "overwrite", "overwrite-partitions"] = "append",
    partition_cols: Optional[List[ColumnInputType]] = None,
    io_config: Optional[IOConfig] = None,
) -> "DataFrame":
    """Writes the DataFrame as CSV files, returning a new DataFrame with paths to the files that were written.

    Files will be written to `<root_dir>/*` with randomly generated UUIDs as the file names.

    Args:
        root_dir (str): root file path to write parquet files to.
        write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace the contents of the root directory with new data. `overwrite-partitions` will replace only the contents in the partitions that are being written to. Defaults to "append".
        partition_cols (Optional[List[ColumnInputType]], optional): How to subpartition each partition further. Defaults to None.
        io_config (Optional[IOConfig], optional): configurations to use when interacting with remote storage.

    Returns:
        DataFrame: The filenames that were written out as strings.

    Note:
        This call is **blocking** and will execute the DataFrame when called

    """
    if write_mode not in ["append", "overwrite", "overwrite-partitions"]:
        raise ValueError(
            f"Only support `append`, `overwrite`, or `overwrite-partitions` mode. {write_mode} is unsupported"
        )
    if write_mode == "overwrite-partitions" and partition_cols is None:
        raise ValueError("Partition columns must be specified to use `overwrite-partitions` mode.")

    io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config

    cols: Optional[List[Expression]] = None
    if partition_cols is not None:
        cols = self.__column_input_to_expression(tuple(partition_cols))

    builder = self._builder.write_tabular(
        root_dir=root_dir,
        partition_cols=cols,
        write_mode=WriteMode.from_str(write_mode),
        file_format=FileFormat.Csv,
        io_config=io_config,
    )

    # Block and write, then retrieve data
    write_df = DataFrame(builder)
    write_df.collect()
    assert write_df._result is not None

    if len(write_df) > 0:
        # Populate and return a new disconnected DataFrame
        result_df = DataFrame(write_df._builder)
        result_df._result_cache = write_df._result_cache
        result_df._preview = write_df._preview
        return result_df
    else:
        from daft import from_pydict
        from daft.recordbatch.recordbatch_io import write_empty_tabular

        file_path = write_empty_tabular(root_dir, FileFormat.Csv, self.schema(), io_config=io_config)

        return from_pydict(
            {
                "path": [file_path],
            }
        )

write_deltalake #

write_deltalake(
    table: Union[
        str,
        Path,
        DataCatalogTable,
        DeltaTable,
        UnityCatalogTable,
    ],
    partition_cols: Optional[List[str]] = None,
    mode: Literal[
        "append", "overwrite", "error", "ignore"
    ] = "append",
    schema_mode: Optional[
        Literal["merge", "overwrite"]
    ] = None,
    name: Optional[str] = None,
    description: Optional[str] = None,
    configuration: Optional[
        Mapping[str, Optional[str]]
    ] = None,
    custom_metadata: Optional[Dict[str, str]] = None,
    dynamo_table_name: Optional[str] = None,
    allow_unsafe_rename: bool = False,
    io_config: Optional[IOConfig] = None,
) -> DataFrame

Writes the DataFrame to a Delta Lake table, returning a new DataFrame with the operations that occurred.

Parameters:

Name Type Description Default
table Union[str, Path, DataCatalogTable, DeltaTable, UnityCatalogTable]

Destination Delta Lake Table or table URI to write dataframe to.

required
partition_cols List[str]

How to subpartition each partition further. If table exists, expected to match table's existing partitioning scheme, otherwise creates the table with specified partition columns. Defaults to None.

None
mode str

Operation mode of the write. append will add new data, overwrite will replace table with new data, error will raise an error if table already exists, and ignore will not write anything if table already exists. Defaults to append.

'append'
schema_mode str

Schema mode of the write. If set to overwrite, allows replacing the schema of the table when doing mode=overwrite. Schema mode merge is currently not supported.

None
name str

User-provided identifier for this table.

None
description str

User-provided description for this table.

None
configuration Mapping[str, Optional[str]]

A map containing configuration options for the metadata action.

None
custom_metadata Dict[str, str]

Custom metadata to add to the commit info.

None
dynamo_table_name str

Name of the DynamoDB table to be used as the locking provider if writing to S3.

None
allow_unsafe_rename bool

Whether to allow unsafe rename when writing to S3 or local disk. Defaults to False.

False
io_config IOConfig

configurations to use when interacting with remote storage.

None

Returns:

Name Type Description
DataFrame DataFrame

The operations that occurred with this write.

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
@DataframePublicAPI
def write_deltalake(
    self,
    table: Union[str, pathlib.Path, "DataCatalogTable", "deltalake.DeltaTable", "UnityCatalogTable"],
    partition_cols: Optional[List[str]] = None,
    mode: Literal["append", "overwrite", "error", "ignore"] = "append",
    schema_mode: Optional[Literal["merge", "overwrite"]] = None,
    name: Optional[str] = None,
    description: Optional[str] = None,
    configuration: Optional[Mapping[str, Optional[str]]] = None,
    custom_metadata: Optional[Dict[str, str]] = None,
    dynamo_table_name: Optional[str] = None,
    allow_unsafe_rename: bool = False,
    io_config: Optional[IOConfig] = None,
) -> "DataFrame":
    """Writes the DataFrame to a [Delta Lake](https://docs.delta.io/latest/index.html) table, returning a new DataFrame with the operations that occurred.

    Args:
        table (Union[str, pathlib.Path, DataCatalogTable, deltalake.DeltaTable, UnityCatalogTable]): Destination [Delta Lake Table](https://delta-io.github.io/delta-rs/api/delta_table/) or table URI to write dataframe to.
        partition_cols (List[str], optional): How to subpartition each partition further. If table exists, expected to match table's existing partitioning scheme, otherwise creates the table with specified partition columns. Defaults to None.
        mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace table with new data, `error` will raise an error if table already exists, and `ignore` will not write anything if table already exists. Defaults to `append`.
        schema_mode (str, optional): Schema mode of the write. If set to `overwrite`, allows replacing the schema of the table when doing `mode=overwrite`. Schema mode `merge` is currently not supported.
        name (str, optional): User-provided identifier for this table.
        description (str, optional): User-provided description for this table.
        configuration (Mapping[str, Optional[str]], optional): A map containing configuration options for the metadata action.
        custom_metadata (Dict[str, str], optional): Custom metadata to add to the commit info.
        dynamo_table_name (str, optional): Name of the DynamoDB table to be used as the locking provider if writing to S3.
        allow_unsafe_rename (bool, optional): Whether to allow unsafe rename when writing to S3 or local disk. Defaults to False.
        io_config (IOConfig, optional): configurations to use when interacting with remote storage.

    Returns:
        DataFrame: The operations that occurred with this write.

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    import json

    import deltalake
    import pyarrow as pa
    from deltalake.schema import _convert_pa_schema_to_delta
    from deltalake.writer import AddAction, try_get_deltatable, write_deltalake_pyarrow
    from packaging.version import parse

    from daft import from_pydict
    from daft.dependencies import unity_catalog
    from daft.filesystem import get_protocol_from_path
    from daft.io import DataCatalogTable
    from daft.io._deltalake import large_dtypes_kwargs
    from daft.io.object_store_options import io_config_to_storage_options

    def _create_metadata_param(metadata: Optional[Dict[str, str]]):
        """From deltalake>=0.20.0 onwards, custom_metadata has to be passed as CommitProperties.

        Args:
            metadata

        Returns:
            DataFrame: metadata for deltalake<0.20.0, otherwise CommitProperties with custom_metadata
        """
        if parse(deltalake.__version__) < parse("0.20.0"):
            return metadata
        else:
            from deltalake import CommitProperties

            return CommitProperties(custom_metadata=metadata)

    if schema_mode == "merge":
        raise ValueError("Schema mode' merge' is not currently supported for write_deltalake.")

    if parse(deltalake.__version__) < parse("0.14.0"):
        raise ValueError(f"Write delta lake is only supported on deltalake>=0.14.0, found {deltalake.__version__}")

    io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config

    # Retrieve table_uri and storage_options from various backends
    table_uri: str
    storage_options: dict

    if isinstance(table, deltalake.DeltaTable):
        table_uri = table.table_uri
        storage_options = table._storage_options or {}
        new_storage_options = io_config_to_storage_options(io_config, table_uri)
        storage_options.update(new_storage_options or {})
    else:
        if isinstance(table, str):
            table_uri = table
        elif isinstance(table, pathlib.Path):
            table_uri = str(table)
        elif unity_catalog.module_available() and isinstance(table, unity_catalog.UnityCatalogTable):
            table_uri = table.table_uri
            io_config = table.io_config
        elif isinstance(table, DataCatalogTable):
            table_uri = table.table_uri(io_config)
        else:
            raise ValueError(f"Expected table to be a path or a DeltaTable, received: {type(table)}")

        if io_config is None:
            raise ValueError(
                "io_config was not provided to write_deltalake and could not be retrieved from defaults."
            )

        storage_options = io_config_to_storage_options(io_config, table_uri) or {}
        table = try_get_deltatable(table_uri, storage_options=storage_options)

    # see: https://delta-io.github.io/delta-rs/usage/writing/writing-to-s3-with-locking-provider/
    scheme = get_protocol_from_path(table_uri)
    if scheme == "s3" or scheme == "s3a":
        if dynamo_table_name is not None:
            storage_options["AWS_S3_LOCKING_PROVIDER"] = "dynamodb"
            storage_options["DELTA_DYNAMO_TABLE_NAME"] = dynamo_table_name
        else:
            storage_options["AWS_S3_ALLOW_UNSAFE_RENAME"] = "true"

            if not allow_unsafe_rename:
                warnings.warn("No DynamoDB table specified for Delta Lake locking. Defaulting to unsafe writes.")
    elif scheme == "file":
        if allow_unsafe_rename:
            storage_options["MOUNT_ALLOW_UNSAFE_RENAME"] = "true"

    pyarrow_schema = pa.schema((f.name, f.dtype.to_arrow_dtype()) for f in self.schema())

    large_dtypes = True
    delta_schema = _convert_pa_schema_to_delta(pyarrow_schema, **large_dtypes_kwargs(large_dtypes))

    if table:
        if partition_cols and partition_cols != table.metadata().partition_columns:
            raise ValueError(
                f"Expected partition columns to match that of the existing table ({table.metadata().partition_columns}), but received: {partition_cols}"
            )
        else:
            partition_cols = table.metadata().partition_columns

        table.update_incremental()

        table_schema = table.schema().to_pyarrow(as_large_types=large_dtypes)
        if delta_schema != table_schema and not (mode == "overwrite" and schema_mode == "overwrite"):
            raise ValueError(
                "Schema of data does not match table schema\n"
                f"Data schema:\n{delta_schema}\nTable Schema:\n{table_schema}"
            )
        if mode == "error":
            raise AssertionError("Delta table already exists, write mode set to error.")
        elif mode == "ignore":
            return from_pydict(
                {
                    "operation": pa.array([], type=pa.string()),
                    "rows": pa.array([], type=pa.int64()),
                    "file_size": pa.array([], type=pa.int64()),
                    "file_name": pa.array([], type=pa.string()),
                }
            )
        version = table.version() + 1
    else:
        version = 0

    if partition_cols is not None:
        for c in partition_cols:
            if self.schema()[c].dtype == DataType.binary():
                raise NotImplementedError("Binary partition columns are not yet supported for Delta Lake writes")

    builder = self._builder.write_deltalake(
        table_uri,
        mode,
        version,
        large_dtypes,
        io_config=io_config,
        partition_cols=partition_cols,
    )
    write_df = DataFrame(builder)
    write_df.collect()

    write_result = write_df.to_pydict()
    assert "add_action" in write_result
    add_actions: List[AddAction] = write_result["add_action"]

    operations = []
    paths = []
    rows = []
    sizes = []

    for add_action in add_actions:
        stats = json.loads(add_action.stats)
        operations.append("ADD")
        paths.append(add_action.path)
        rows.append(stats["numRecords"])
        sizes.append(add_action.size)

    if table is None:
        write_deltalake_pyarrow(
            table_uri,
            delta_schema,
            add_actions,
            mode,
            partition_cols or [],
            name,
            description,
            configuration,
            storage_options,
            custom_metadata,
        )
    else:
        if mode == "overwrite":
            old_actions = table.get_add_actions()
            old_actions_dict = old_actions.to_pydict()
            for i in range(old_actions.num_rows):
                operations.append("DELETE")
                paths.append(old_actions_dict["path"][i])
                rows.append(old_actions_dict["num_records"][i])
                sizes.append(old_actions_dict["size_bytes"][i])

        metadata_param = _create_metadata_param(custom_metadata)
        table._table.create_write_transaction(
            add_actions, mode, partition_cols or [], delta_schema, None, metadata_param
        )
        table.update_incremental()

    with_operations = from_pydict(
        {
            "operation": pa.array(operations, type=pa.string()),
            "rows": pa.array(rows, type=pa.int64()),
            "file_size": pa.array(sizes, type=pa.int64()),
            "file_name": pa.array([os.path.basename(fp) for fp in paths], type=pa.string()),
        }
    )

    return with_operations

write_iceberg #

write_iceberg(
    table: Table,
    mode: str = "append",
    io_config: Optional[IOConfig] = None,
) -> DataFrame

Writes the DataFrame to an Iceberg table, returning a new DataFrame with the operations that occurred.

Can be run in either append or overwrite mode which will either appends the rows in the DataFrame or will delete the existing rows and then append the DataFrame rows respectively.

Parameters:

Name Type Description Default
table Table

Destination PyIceberg Table to write dataframe to.

required
mode str

Operation mode of the write. append or overwrite Iceberg Table. Defaults to append.

'append'
io_config IOConfig

A custom IOConfig to use when accessing Iceberg object storage data. If provided, configurations set in table are ignored.

None

Returns:

Name Type Description
DataFrame DataFrame

The operations that occurred with this write.

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
@DataframePublicAPI
def write_iceberg(
    self, table: "pyiceberg.table.Table", mode: str = "append", io_config: Optional[IOConfig] = None
) -> "DataFrame":
    """Writes the DataFrame to an [Iceberg](https://iceberg.apache.org/docs/nightly/) table, returning a new DataFrame with the operations that occurred.

    Can be run in either `append` or `overwrite` mode which will either appends the rows in the DataFrame or will delete the existing rows and then append the DataFrame rows respectively.

    Args:
        table (pyiceberg.table.Table): Destination [PyIceberg Table](https://py.iceberg.apache.org/reference/pyiceberg/table/#pyiceberg.table.Table) to write dataframe to.
        mode (str, optional): Operation mode of the write. `append` or `overwrite` Iceberg Table. Defaults to `append`.
        io_config (IOConfig, optional): A custom IOConfig to use when accessing Iceberg object storage data. If provided, configurations set in `table` are ignored.

    Returns:
        DataFrame: The operations that occurred with this write.

    Note:
        This call is **blocking** and will execute the DataFrame when called

    """
    import pyarrow as pa
    import pyiceberg
    from packaging.version import parse

    from daft.io._iceberg import _convert_iceberg_file_io_properties_to_io_config

    if len(table.spec().fields) > 0 and parse(pyiceberg.__version__) < parse("0.7.0"):
        raise ValueError("pyiceberg>=0.7.0 is required to write to a partitioned table")

    if parse(pyiceberg.__version__) < parse("0.6.0"):
        raise ValueError(f"Write Iceberg is only supported on pyiceberg>=0.6.0, found {pyiceberg.__version__}")

    if parse(pa.__version__) < parse("12.0.1"):
        raise ValueError(
            f"Write Iceberg is only supported on pyarrow>=12.0.1, found {pa.__version__}. See this issue for more information: https://github.com/apache/arrow/issues/37054#issuecomment-1668644887"
        )

    if mode not in ["append", "overwrite"]:
        raise ValueError(f"Only support `append` or `overwrite` mode. {mode} is unsupported")

    io_config = (
        _convert_iceberg_file_io_properties_to_io_config(table.io.properties) if io_config is None else io_config
    )
    io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config

    operations = []
    path = []
    rows = []
    size = []

    builder = self._builder.write_iceberg(table, io_config)
    write_df = DataFrame(builder)
    write_df.collect()

    write_result = write_df.to_pydict()
    assert "data_file" in write_result
    data_files = write_result["data_file"]

    if mode == "overwrite":
        deleted_files = table.scan().plan_files()
    else:
        deleted_files = []

    schema = table.schema()
    partitioning: Dict[str, list] = {schema.find_field(field.source_id).name: [] for field in table.spec().fields}

    for data_file in data_files:
        operations.append("ADD")
        path.append(data_file.file_path)
        rows.append(data_file.record_count)
        size.append(data_file.file_size_in_bytes)

        for field in partitioning.keys():
            partitioning[field].append(getattr(data_file.partition, field, None))

    for pf in deleted_files:
        data_file = pf.file
        operations.append("DELETE")
        path.append(data_file.file_path)
        rows.append(data_file.record_count)
        size.append(data_file.file_size_in_bytes)

        for field in partitioning.keys():
            partitioning[field].append(getattr(data_file.partition, field, None))

    if parse(pyiceberg.__version__) >= parse("0.7.0"):
        from pyiceberg.table import ALWAYS_TRUE, TableProperties

        if parse(pyiceberg.__version__) >= parse("0.8.0"):
            from pyiceberg.utils.properties import property_as_bool

            property_as_bool = property_as_bool
        else:
            from pyiceberg.table import PropertyUtil

            property_as_bool = PropertyUtil.property_as_bool

        tx = table.transaction()

        if mode == "overwrite":
            tx.delete(delete_filter=ALWAYS_TRUE)

        update_snapshot = tx.update_snapshot()

        manifest_merge_enabled = mode == "append" and property_as_bool(
            tx.table_metadata.properties,
            TableProperties.MANIFEST_MERGE_ENABLED,
            TableProperties.MANIFEST_MERGE_ENABLED_DEFAULT,
        )

        append_method = update_snapshot.merge_append if manifest_merge_enabled else update_snapshot.fast_append

        with append_method() as append_files:
            for data_file in data_files:
                append_files.append_data_file(data_file)

        tx.commit_transaction()
    else:
        from pyiceberg.table import _MergingSnapshotProducer
        from pyiceberg.table.snapshots import Operation

        operations_map = {
            "append": Operation.APPEND,
            "overwrite": Operation.OVERWRITE,
        }

        merge = _MergingSnapshotProducer(operation=operations_map[mode], table=table)

        for data_file in data_files:
            merge.append_data_file(data_file)

        merge.commit()

    with_operations = {
        "operation": pa.array(operations, type=pa.string()),
        "rows": pa.array(rows, type=pa.int64()),
        "file_size": pa.array(size, type=pa.int64()),
        "file_name": pa.array([fp for fp in path], type=pa.string()),
    }

    if partitioning:
        with_operations["partitioning"] = pa.StructArray.from_arrays(
            partitioning.values(), names=partitioning.keys()
        )

    from daft import from_pydict

    # NOTE: We are losing the history of the plan here.
    # This is due to the fact that the logical plan of the write_iceberg returns datafiles but we want to return the above data
    return from_pydict(with_operations)

write_lance #

write_lance(
    uri: Union[str, Path],
    mode: Literal[
        "create", "append", "overwrite"
    ] = "create",
    io_config: Optional[IOConfig] = None,
    **kwargs,
) -> DataFrame

Writes the DataFrame to a Lance table.

Parameters:

Name Type Description Default
uri Union[str, Path]

The URI of the Lance table to write to

required
mode Literal['create', 'append', 'overwrite']

The write mode. One of "create", "append", or "overwrite"

'create'
io_config IOConfig

configurations to use when interacting with remote storage.

None
**kwargs

Additional keyword arguments to pass to the Lance writer.

{}
Note

write_lance` requires python 3.9 or higher

Examples:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
>>> import daft
>>> df = daft.from_pydict({"a": [1, 2, 3, 4]})
>>> df.write_lance("/tmp/lance/my_table.lance")
╭───────────────┬──────────────────┬─────────────────┬─────────╮
│ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
│ ---           ┆ ---              ┆ ---             ┆ ---     │
│ Int64         ┆ Int64            ┆ Int64           ┆ Int64   │
╞═══════════════╪══════════════════╪═════════════════╪═════════╡
│ 1             ┆ 0                ┆ 1               ┆ 1       │
╰───────────────┴──────────────────┴─────────────────┴─────────╯

(Showing first 1 of 1 rows)
>>> daft.read_lance("/tmp/lance/my_table.lance").collect()
╭───────╮
│ a     │
│ ---   │
│ Int64 │
╞═══════╡
│ 1     │
├╌╌╌╌╌╌╌┤
│ 2     │
├╌╌╌╌╌╌╌┤
│ 3     │
├╌╌╌╌╌╌╌┤
│ 4     │
╰───────╯

(Showing first 4 of 4 rows)
>>> # Pass additional keyword arguments to the Lance writer
>>> # All additional keyword arguments are passed to `lance.write_fragments`
>>> df.write_lance("/tmp/lance/my_table.lance", mode="overwrite", max_bytes_per_file=1024)
╭───────────────┬──────────────────┬─────────────────┬─────────╮
│ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
│ ---           ┆ ---              ┆ ---             ┆ ---     │
│ Int64         ┆ Int64            ┆ Int64           ┆ Int64   │
╞═══════════════╪══════════════════╪═════════════════╪═════════╡
│ 1             ┆ 0                ┆ 1               ┆ 2       │
╰───────────────┴──────────────────┴─────────────────┴─────────╯

(Showing first 1 of 1 rows)
Source code in daft/dataframe/dataframe.py
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
@DataframePublicAPI
def write_lance(
    self,
    uri: Union[str, pathlib.Path],
    mode: Literal["create", "append", "overwrite"] = "create",
    io_config: Optional[IOConfig] = None,
    **kwargs,
) -> "DataFrame":
    """Writes the DataFrame to a Lance table.

    Args:
      uri: The URI of the Lance table to write to
      mode: The write mode. One of "create", "append", or "overwrite"
      io_config (IOConfig, optional): configurations to use when interacting with remote storage.
      **kwargs: Additional keyword arguments to pass to the Lance writer.

    Note:
        write_lance` requires python 3.9 or higher

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"a": [1, 2, 3, 4]})
        >>> df.write_lance("/tmp/lance/my_table.lance")  # doctest: +SKIP
        ╭───────────────┬──────────────────┬─────────────────┬─────────╮
        │ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
        │ ---           ┆ ---              ┆ ---             ┆ ---     │
        │ Int64         ┆ Int64            ┆ Int64           ┆ Int64   │
        ╞═══════════════╪══════════════════╪═════════════════╪═════════╡
        │ 1             ┆ 0                ┆ 1               ┆ 1       │
        ╰───────────────┴──────────────────┴─────────────────┴─────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)
        >>> daft.read_lance("/tmp/lance/my_table.lance").collect()  # doctest: +SKIP
        ╭───────╮
        │ a     │
        │ ---   │
        │ Int64 │
        ╞═══════╡
        │ 1     │
        ├╌╌╌╌╌╌╌┤
        │ 2     │
        ├╌╌╌╌╌╌╌┤
        │ 3     │
        ├╌╌╌╌╌╌╌┤
        │ 4     │
        ╰───────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)
        >>> # Pass additional keyword arguments to the Lance writer
        >>> # All additional keyword arguments are passed to `lance.write_fragments`
        >>> df.write_lance("/tmp/lance/my_table.lance", mode="overwrite", max_bytes_per_file=1024)  # doctest: +SKIP
        ╭───────────────┬──────────────────┬─────────────────┬─────────╮
        │ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
        │ ---           ┆ ---              ┆ ---             ┆ ---     │
        │ Int64         ┆ Int64            ┆ Int64           ┆ Int64   │
        ╞═══════════════╪══════════════════╪═════════════════╪═════════╡
        │ 1             ┆ 0                ┆ 1               ┆ 2       │
        ╰───────────────┴──────────────────┴─────────────────┴─────────╯
        <BLANKLINE>
        (Showing first 1 of 1 rows)
    """
    from daft.dataframe.lance_data_sink import LanceDataSink

    sink = LanceDataSink(uri, self.schema(), mode, io_config, **kwargs)
    return self.write_sink(sink)

write_parquet #

write_parquet(
    root_dir: Union[str, Path],
    compression: str = "snappy",
    write_mode: Literal[
        "append", "overwrite", "overwrite-partitions"
    ] = "append",
    partition_cols: Optional[List[ColumnInputType]] = None,
    io_config: Optional[IOConfig] = None,
) -> DataFrame

Writes the DataFrame as parquet files, returning a new DataFrame with paths to the files that were written.

Files will be written to <root_dir>/* with randomly generated UUIDs as the file names.

Parameters:

Name Type Description Default
root_dir str

root file path to write parquet files to.

required
compression str

compression algorithm. Defaults to "snappy".

'snappy'
write_mode str

Operation mode of the write. append will add new data, overwrite will replace the contents of the root directory with new data. overwrite-partitions will replace only the contents in the partitions that are being written to. Defaults to "append".

'append'
partition_cols Optional[List[ColumnInputType]]

How to subpartition each partition further. Defaults to None.

None
io_config Optional[IOConfig]

configurations to use when interacting with remote storage.

None

Returns:

Name Type Description
DataFrame DataFrame

The filenames that were written out as strings.

Note

This call is blocking and will execute the DataFrame when called

Source code in daft/dataframe/dataframe.py
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
@DataframePublicAPI
def write_parquet(
    self,
    root_dir: Union[str, pathlib.Path],
    compression: str = "snappy",
    write_mode: Literal["append", "overwrite", "overwrite-partitions"] = "append",
    partition_cols: Optional[List[ColumnInputType]] = None,
    io_config: Optional[IOConfig] = None,
) -> "DataFrame":
    """Writes the DataFrame as parquet files, returning a new DataFrame with paths to the files that were written.

    Files will be written to `<root_dir>/*` with randomly generated UUIDs as the file names.

    Args:
        root_dir (str): root file path to write parquet files to.
        compression (str, optional): compression algorithm. Defaults to "snappy".
        write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace the contents of the root directory with new data. `overwrite-partitions` will replace only the contents in the partitions that are being written to. Defaults to "append".
        partition_cols (Optional[List[ColumnInputType]], optional): How to subpartition each partition further. Defaults to None.
        io_config (Optional[IOConfig], optional): configurations to use when interacting with remote storage.

    Returns:
        DataFrame: The filenames that were written out as strings.

    Note:
        This call is **blocking** and will execute the DataFrame when called
    """
    if write_mode not in ["append", "overwrite", "overwrite-partitions"]:
        raise ValueError(
            f"Only support `append`, `overwrite`, or `overwrite-partitions` mode. {write_mode} is unsupported"
        )
    if write_mode == "overwrite-partitions" and partition_cols is None:
        raise ValueError("Partition columns must be specified to use `overwrite-partitions` mode.")

    io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config

    cols: Optional[List[Expression]] = None
    if partition_cols is not None:
        cols = self.__column_input_to_expression(tuple(partition_cols))

    builder = self._builder.write_tabular(
        root_dir=root_dir,
        partition_cols=cols,
        write_mode=WriteMode.from_str(write_mode),
        file_format=FileFormat.Parquet,
        compression=compression,
        io_config=io_config,
    )
    # Block and write, then retrieve data
    write_df = DataFrame(builder)
    write_df.collect()
    assert write_df._result is not None

    if len(write_df) > 0:
        # Populate and return a new disconnected DataFrame
        result_df = DataFrame(write_df._builder)
        result_df._result_cache = write_df._result_cache
        result_df._preview = write_df._preview
        return result_df
    else:
        from daft import from_pydict
        from daft.recordbatch.recordbatch_io import write_empty_tabular

        file_path = write_empty_tabular(
            root_dir, FileFormat.Parquet, self.schema(), compression=compression, io_config=io_config
        )

        return from_pydict(
            {
                "path": [file_path],
            }
        )

write_sink #

write_sink(sink: DataSink[T]) -> DataFrame

Writes the DataFrame to the given DataSink.

Parameters:

Name Type Description Default
sink DataSink[T]

The DataSink to write to.

required

Returns:

Name Type Description
DataFrame DataFrame

A dataframe from the micropartition returned by the DataSink's .finalize() method.

Source code in daft/dataframe/dataframe.py
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
@DataframePublicAPI
def write_sink(self, sink: "DataSink[T]") -> "DataFrame":
    """Writes the DataFrame to the given DataSink.

    Args:
        sink: The DataSink to write to.

    Returns:
        DataFrame: A dataframe from the micropartition returned by the DataSink's `.finalize()` method.
    """
    sink.start()

    builder = self._builder.write_datasink(sink.name(), sink)
    write_df = DataFrame(builder)
    write_df.collect()

    results = write_df.to_pydict()
    assert "write_results" in results
    micropartition = sink.finalize(results["write_results"])
    if micropartition.schema() != sink.schema():
        raise ValueError(
            f"Schema mismatch between the data sink's schema and the result's schema:\nSink schema:\n{sink.schema()}\nResult schema:\n{micropartition.schema()}"
        )
    # TODO(desmond): Connect the old and new logical plan builders so that a .explain() shows the
    # plan from the source all the way to the sink to the sink's results. In theory we can do this
    # for all other sinks too.
    write_plan_builder = to_logical_plan_builder(micropartition)
    return DataFrame(write_plan_builder)