polars.Expr.map

Expr.map(f: Callable[[polars.internals.series.Series], polars.internals.series.Series], return_dtype: Optional[Type[polars.datatypes.DataType]] = None, agg_list: bool = False) polars.internals.expr.Expr

Apply a custom python function. This function must produce a Series. Any other value will be stored as null/missing. If you want to apply a function over single values, consider using apply.

[read more in the book](https://pola-rs.github.io/polars-book/user-guide/howcani/apply/udfs.html)

Parameters
f

Lambda/ function to apply.

return_dtype

Dtype of the output Series.

agg_list