[jira] [Created] (ARROW-9594) [Python] DictionaryArray.to_numpy does not correctly convert null indexes to null values

["Steve M. Kim (Jira)" <ji...@apache.org>]

Steve M. Kim created ARROW-9594:
-----------------------------------

             Summary: [Python] DictionaryArray.to_numpy does not correctly convert null indexes to null values
                 Key: ARROW-9594
                 URL: https://issues.apache.org/jira/browse/ARROW-9594
             Project: Apache Arrow
          Issue Type: Bug
    Affects Versions: 1.0.0
            Reporter: Steve M. Kim


Example
{code:java}

 >>> a = pa.DictionaryArray.from_arrays(pa.array([0, 1, None, 0], type=pa.int32()), pa.array(['foo', 'bar']))
>>> a
<pyarrow.lib.DictionaryArray object at 0x7f12fc94ccf0>-- dictionary:
  [
    "foo",
    "bar"
  ]
-- indices:
  [
    0,
    1,
    null,
    0
  ]
>>> a.to_pandas()  # this works
0    foo
1    bar
2    NaN
3    foo
dtype: category
Categories (2, object): [foo, bar]
>>> a.to_numpy(zero_copy_only=False)  # this is broken
array(['foo', 'bar', 'bar', 'foo'], dtype=object)

{code}
 



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