FIX ColumnTransformer.fit_transform for polars.DataFrame missing a .size attribute in sparse stacking #32188
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…ize attribute in sparse stacking
…r polars/pandas DataFrame
…e="pandas" is a valid input
adrinjalali
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Sep 24, 2025
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Please add a changelog entry based on our guidelines: https://github.com/scikit-learn/scikit-learn/blob/main/doc/whats_new/upcoming_changes/README.md
Otherwise LGTM.
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Thanks @adrinjalali, I added the changelog entry! |
adrinjalali
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Oct 6, 2025
jeremiedbb
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Thanks for the PR @ph-ll-pp. I just pushed a commit with a few nitpicks. LGTM
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@jeremiedbb Thanks for the nitpicks, much appreciated! |
Tunahanyrd
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Oct 28, 2025
…arse output (scikit-learn#32188) Co-authored-by: Jérémie du Boisberranger <[email protected]>
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Reference Issues/PRs
Fixes #32155
What does this implement/fix?
ColumnTransformer.fit_transform failed on polars.DataFrames, if some transformers, but not all, returned a sparse matrix/array. In this case, the function tried to access a .size attribute, which is not implemented for polars.DataFrame. The bug was fixed by instead resorting to the .shape attribute which is universally implemented across numpy/pandas/polars. Tests in test_column_transformer_sparse_stacking were updated to not only test stacking of sparse matrix outputs from numpy inputs, but also from polars and pandas inputs.
Any other comments?
I also improved the docstring of the internal _convert_container helper function to indicate constructor_name="pandas" is a valid input.