Github user zero323 commented on a diff in the pull request:
https://github.com/apache/spark/pull/16533#discussion_r97954697
--- Diff: python/pyspark/sql/functions.py ---
@@ -1862,9 +1862,33 @@ def udf(f, returnType=StringType()):
>>> slen = udf(lambda s: len(s), IntegerType())
>>> df.select(slen(df.name).alias('slen')).collect()
[Row(slen=5), Row(slen=3)]
+ >>> @udf
+ ... def to_upper(s):
+ ... if s is not None:
+ ... return s.upper()
+ ...
+ >>> @udf(returnType=IntegerType())
+ ... def add_one(x):
+ ... if x is not None:
+ ... return x + 1
+ ...
"""
return UserDefinedFunction(f, returnType)
+
[email protected](_udf)
+def udf(f=None, returnType=StringType()):
--- End diff --
We can, but I am not sure if we should keep the original version or
acknowledge change of behavior and use potential merge version.
Regarding docstring I am a bit reluctant. It can be documented for dev
purposes but any user facing doc will have to expose ugly implementation
details.
def udf(
f: typing.Union[None, typing.Callable, pyspark.sql.types.DataType],
returnType: pyspark.sql.types.DataType=StringType()
) -> Union[types.FunctionType, functools.partial]:
...
Maybe I a wrong but it can bring more confusion than it is worth. We can of
course move `_udf` docstring and skip wrapping (we considered different
implementations where signatures differed) but of course it won't be accurate.
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