[jira] [Created] (ARROW-9664) Argument types_mapper of pyarrow.Array.to_pandas() has no effect

["Adrien Hoarau (Jira)" <ji...@apache.org>]

Adrien Hoarau created ARROW-9664:
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             Summary: Argument types_mapper of pyarrow.Array.to_pandas() has no effect
                 Key: ARROW-9664
                 URL: https://issues.apache.org/jira/browse/ARROW-9664
             Project: Apache Arrow
          Issue Type: Bug
          Components: Python
    Affects Versions: 1.0.0
         Environment: pyarrow: 1.0.0
pandas: 1.0.5
python: sys.version_info(major=3, minor=8, micro=2, releaselevel='final', serial=0)
            Reporter: Adrien Hoarau


Arrow structures (Array, ChunkedArray, Table) have a types_mapper argument in their to_pandas method. It works for Table, but doesn't seem to get called for Array or ChunkedArray:
{code:java}
import pandas as pd
import pyarrow

data = pd.Series([0, None, 2], dtype=pd.Int32Dtype(), name='foo')

def convert_types(arrow_type):
     raise ValueError("Function got called")


pyarrow.Table.from_pandas(data.to_frame()).to_pandas(types_mapper=convert_types)

Traceback (most recent call last):
  File "/home/adrien/.pyenv/versions/complete/lib/python3.8/site-packages/IPython/core/interactiveshell.py", line 3331, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-6-d1e3e1f45f69>", line 1, in <module>
    pyarrow.Table.from_pandas(data.to_frame()).to_pandas(types_mapper=convert_types)
  File "pyarrow/array.pxi", line 715, in pyarrow.lib._PandasConvertible.to_pandas
  File "pyarrow/table.pxi", line 1565, in pyarrow.lib.Table._to_pandas
  File "/home/adrien/.pyenv/versions/complete/lib/python3.8/site-packages/pyarrow/pandas_compat.py", line 771, in table_to_blockmanager
    ext_columns_dtypes = _get_extension_dtypes(
  File "/home/adrien/.pyenv/versions/complete/lib/python3.8/site-packages/pyarrow/pandas_compat.py", line 840, in _get_extension_dtypes
    pandas_dtype = types_mapper(typ)
  File "<ipython-input-5-5a9760e8753f>", line 2, in convert_types
    raise ValueError("Function got called")
ValueError: Function got called

pyarrow.Int32Array.from_pandas(data).to_pandas(types_mapper=convert_types)

0    0.0
1    NaN
2    2.0
dtype: float64{code}



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