daft.functions.map_keys#

def map_keys(expr: Expression) -> Expression:
    """Returns a list of all keys in the map.

    Args:
        expr: the map expression to get from

    Returns:
        Expression: the keys list expression

    Examples:
        >>> import pyarrow as pa
        >>> import daft
        >>> pa_array = pa.array([[("a", 1), ("b", 2)], [("c", 3)], [], None], type=pa.map_(pa.string(), pa.int64()))
        >>> df = daft.from_arrow(pa.table({"map_col": pa_array}))
        >>> df = df.with_column("keys", df["map_col"].map_keys())
        >>> df.show()
        ╭────────────────────┬──────────────╮
        │ map_col            ┆ keys         │
        │ ---                ┆ ---          │
        │ Map[String: Int64] ┆ List[String] │
        ╞════════════════════╪══════════════╡
        │ {"a": 1, "b": 2}   ┆ [a, b]       │
        ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ {"c": 3}           ┆ [c]          │
        ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ {}                 ┆ None         │
        ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ None               ┆ None         │
        ╰────────────────────┴──────────────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)

    """
    return Expression._from_pyexpr(expr._expr.map_keys())