daft.Expression.list.value_counts#
- Expression.list.value_counts() Expression[source]#
Counts the occurrences of each unique value in the list.
- Returns:
- A Map<X, UInt64> expression where the keys are unique elements from the
original list of type X, and the values are UInt64 counts representing the number of times each element appears in the list.
- Return type:
Expression
Note
This function does not work for nested types. For example, it will not produce a map with lists as keys.
Example
>>> import daft >>> df = daft.from_pydict({"letters": [["a", "b", "a"], ["b", "c", "b", "c"]]}) >>> df.with_column("value_counts", df["letters"].list.value_counts()).collect() ╭──────────────┬───────────────────╮ │ letters ┆ value_counts │ │ --- ┆ --- │ │ List[Utf8] ┆ Map[Utf8: UInt64] │ ╞══════════════╪═══════════════════╡ │ [a, b, a] ┆ [{key: a, │ │ ┆ value: 2, │ │ ┆ }, {key: … │ ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤ │ [b, c, b, c] ┆ [{key: b, │ │ ┆ value: 2, │ │ ┆ }, {key: … │ ╰──────────────┴───────────────────╯ (Showing first 2 of 2 rows)