polars.DataFrame.apply#
- DataFrame.apply(
- function: Callable[[tuple[Any, ...]], Any],
- return_dtype: PolarsDataType | None = None,
- *,
- inference_size: int = 256,
Apply a custom/user-defined function (UDF) over the rows of the DataFrame.
Deprecated since version 0.19.0: This method has been renamed to
DataFrame.map_rows().- Parameters:
- function
Custom function or lambda.
- return_dtype
Output type of the operation. If none given, Polars tries to infer the type.
- inference_size
Only used in the case when the custom function returns rows. This uses the first n rows to determine the output schema