FIX apply check_array before stacking in ColumnTransformer #27671
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Reference Issues/PRs
fixes #27482
What does this implement/fix? Explain your changes.
The
ColumnTransformer(withoutset_output(transform="pandas")), when it transforms pandas columns that containpd.NA, outputs arrays of dtypeobjectthat containpd.NA, which can cause subsequent estimators in a pipeline to fail becausecheck_array(dtype="numeric")raises a TypeError on such arrays.The proposal here is to apply
check_array(dtype=None)on the transformers' outputs before performing the horizontal stacking. This will convertpd.Float64tonp.float64andpd.NAtonp.nanAny other comments?
Another option is to forbid
pd.NAin the individual transformers' output if the ColumnTransformer does not have its output transform set to "pandas". Before performing thehstackwe can check forpd.NAand raise if any are found.This still has the drawback that the output for
pd.Float64columns (without missing values) will beobjectrather thannp.float64