DOC add a note for fit no-op in FunctionTransformer
@@ -1129,6 +1129,7 @@ a transformer that applies a log transformation in a pipeline, do::
>>> from sklearn.preprocessing import FunctionTransformer
>>> transformer = FunctionTransformer(np.log1p, validate=True)
>>> X = np.array([[0, 1], [2, 3]])
+ >>> # Since FunctionTransformer is no-op during fit, we can call transform directly
>>> transformer.transform(X)
array([[0. , 0.69314718],
[1.09861229, 1.38629436]])
