daft.functions.list_map#

def list_map(list_expr: Expression, mapper: Expression) -> Expression:
    """Evaluates an expression on all elements in the list.

    Args:
        list_expr (List Expression): expression to map over.
        mapper: Expression to run. You can select the element with `daft.element()`

    Returns:
        Expression (List Expression): an expression representing the mapped list.

    Examples:
        >>> import daft
        >>> from daft.functions import list_map, upper
        >>> df = daft.from_pydict({"letters": [["a", "b", "a"], ["b", "c", "b", "c"]]})
        >>> df.with_column("letters_capitalized", list_map(df["letters"], upper(daft.element()))).collect()
        ╭──────────────┬─────────────────────╮
        │ letters      ┆ letters_capitalized │
        │ ---          ┆ ---                 │
        │ List[String] ┆ List[String]        │
        ╞══════════════╪═════════════════════╡
        │ [a, b, a]    ┆ [A, B, A]           │
        ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
        │ [b, c, b, c] ┆ [B, C, B, C]        │
        ╰──────────────┴─────────────────────╯
        <BLANKLINE>
        (Showing first 2 of 2 rows)
    """
    return Expression._call_builtin_scalar_fn("list_map", list_expr, mapper)