polars.apply#
- polars.apply(exprs: Sequence[str | polars.internals.expr.expr.Expr], f: Callable[[Sequence[Series]], Union[Series, Any]], return_dtype: Optional[type[polars.datatypes.DataType]] = None) Expr[source]#
Apply a custom/user-defined function (UDF) in a GroupBy context.
Depending on the context it has the following behavior:
- Select
Don’t use apply, use map
- GroupBy
expected type f: Callable[[Series], Series] Applies a python function over each group.
- Parameters:
- exprs
Input Series to f
- f
Function to apply over the input
- return_dtype
dtype of the output Series
- Returns:
- Expr