BUG: Fix inconsistency of converting empty categorical with dtype_backend='pyarrow' #61131
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…pe_backend results in error. Since conversion of non-empty categorical returns categorical of 'numpy_nullable' dtype_backend, now, instead of raising an error, we ensure empty categorical is returned as well.
mroeschke
reviewed
Mar 17, 2025
mroeschke
reviewed
Mar 17, 2025
pandas/core/dtypes/cast.py
Outdated
| @@ -1143,6 +1143,7 @@ def convert_dtypes( | |||
| base_dtype.kind == "O" # type: ignore[union-attr] | |||
| and input_array.size > 0 | |||
| and isna(input_array).all() | |||
| and not isinstance(input_array.dtype, CategoricalDtype) | |||
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Nit: Could you put this check above the isna(...).all() check as it's less expensive?
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Actually, could you properly add an elif isinstance(inferred_dtype, CategoricalDtype) clause for this type in the above if/else branch?
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I added this to the outer if branch, to skip the arrow dtype conversion for CategoricalDtype.
As mentioned in #59934, the expected behavior of convert_dtypes for CategoricalDtype series essentially ignores the requested pyarrow backend conversion.
mroeschke
reviewed
Mar 17, 2025
Co-authored-by: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
mroeschke
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Dtype Conversions
mroeschke
approved these changes
Mar 17, 2025
|
Thanks @yuanx749 |
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Follows up #59935
doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.