[GitHub] [arrow] AlenkaF commented on issue #34449: [Python] `to_parquet` fails with a category field backed by pyarrow string

["AlenkaF (via GitHub)" <gi...@apache.org>]

AlenkaF commented on issue #34449:
URL: https://github.com/apache/arrow/issues/34449#issuecomment-1455695427

   Thank you for reporting. Yes, this is a known bug in pyarrow and is already being fixed in https://github.com/apache/arrow/issues/33727 with https://github.com/apache/arrow/pull/34289.
   
   Running your example on the linked PR branch:
   
   ```python
   >>> df = pd.DataFrame({"x": [1, 2, 3, 4, 5], "y": list("caaab")})
   >>> df["y"] = df["y"].astype(pd.StringDtype("pyarrow"))
   >>> df["y"] = df["y"].astype("category")
   >>> df.to_parquet("test-arrow.parquet")
   
   >>> pd.read_parquet("test-arrow.parquet")
      x  y
   0  1  c
   1  2  a
   2  3  a
   3  4  a
   4  5  b
   >>> pd.read_parquet("test-arrow.parquet").dtypes
   x       int64
   y    category
   dtype: object
   >>> pd.read_parquet("test-arrow.parquet").dtypes.y
   CategoricalDtype(categories=['a', 'b', 'c'], ordered=False)
   ```


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