[C++][Python] Support for pandas Categoricals with Intervals

[asfimport]

Trying to write a pandas categorical created from pd.cut fails with the following error:

df_test = pd.DataFrame({"cat": pd.cut([1, 2, 3, 4, 5], bins=[2, 4])})
df_test.to_parquet("test.parquet")

File "pyarrow/error.pxi", line 120, in pyarrow.lib.check_status
pyarrow.lib.ArrowNotImplementedError: Unsupported cast from dictionary<values=extension<pandas.interval<ArrowIntervalType>>, indices=int8, ordered=1> to extension<pandas.interval<ArrowIntervalType>> (no available cast function for target type)

The problems seems to be the interval dtype. Specifing the labels keyword solved the problem.

Reporter: Alberto Torres

Related issues:

• [C++][Parquet] Writing DictionaryArrays with ExtensionType to Parquet (relates to)
• [C++] Cast dictionary of extension type to extension type (depends upon)

_{Note: This issue was originally created as ARROW-14569. Please see the migration documentation for further details.}

[asfimport]

David Li / @lidavidm:
Looks like we need a cast from dictionary to extension (at least just looking at the error).

[github-actions]

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