Whether the `apply` function is implemented using the pandas_udf function?

[RainFung]

Whether the apply function is implemented using the pandas_udf function?

[itholic]

Yeah, for some case we use mapInPandas which leveraging the pandas_udf internally.

koalas/databricks/koalas/frame.py

Lines 2557 to 2563 in 07d8462

	if should_use_map_in_pandas:
	output_func = GroupBy._make_pandas_df_builder_func(
	self_applied, apply_func, return_schema, retain_index=True
	)
	sdf = self_applied._internal.to_internal_spark_frame.mapInPandas(
	lambda iterator: map(output_func, iterator), schema=return_schema
	)