daft.Expression.map.get#
- Expression.map.get(key: Expression) Expression[source]#
Retrieves the value for a key in a map column
Example
>>> import pyarrow as pa >>> import daft >>> pa_array = pa.array([[("a", 1)],[],[("b", 2)]], type=pa.map_(pa.string(), pa.int64())) >>> df = daft.from_arrow(pa.table({"map_col": pa_array})) >>> df = df.with_column("a", df["map_col"].map.get("a")) >>> df.show() ╭──────────────────┬───────╮ │ map_col ┆ a │ │ --- ┆ --- │ │ Map[Utf8: Int64] ┆ Int64 │ ╞══════════════════╪═══════╡ │ [{key: a, ┆ 1 │ │ value: 1, ┆ │ │ }] ┆ │ ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤ │ [] ┆ None │ ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤ │ [{key: b, ┆ None │ │ value: 2, ┆ │ │ }] ┆ │ ╰──────────────────┴───────╯ (Showing first 3 of 3 rows)
- Parameters:
key – the key to retrieve
- Returns:
the value expression
- Return type:
Expression