grp.get_group: IndexError: positional indexers are out-of-bounds

[anmyachev]

Reproducer:

import pandas
pandas_df = pandas.DataFrame(
     {
         "col1": [0, 3, 2, 3],
         "col2": [4, 1, 6, 7],
         "col3": [3, 8, 2, 10],
         "col4": [1, 13, 6, 15],
         "col5": [-4, 5, 6, -7],
     }
)
pandas_groupby = pandas_df.groupby(axis=1, by=[1,2,3,2,1]) 
print(pandas_groupby.groups)  # <- {1: ['col1', 'col5'], 2: ['col2', 'col4'], 3: ['col3']}
pandas_groupby.get_group(1)  # <- IndexError: positional indexers are out-of-bounds

pandas 2.1.0rc0

>>> pandas_groupby.get_group(1)    
Traceback (most recent call last):
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\indexing.py", line 1675, in _get_list_axis
    return self.obj._take_with_is_copy(key, axis=axis)
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\generic.py", line 4088, in _take_with_is_copy
    result = self.take(indices=indices, axis=axis)
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\generic.py", line 4068, in take
    new_data = self._mgr.take(
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\internals\managers.py", line 874, in take
    indexer = maybe_convert_indices(indexer, n, verify=verify)
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\indexers\utils.py", line 282, in maybe_convert_indices
    raise IndexError("indices are out-of-bounds")
IndexError: indices are out-of-bounds

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\groupby\groupby.py", line 1060, in get_group
    return self._selected_obj.iloc[inds]
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\indexing.py", line 1152, in __getitem__
    return self._getitem_axis(maybe_callable, axis=axis)
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\indexing.py", line 1704, in _getitem_axis
    return self._get_list_axis(key, axis=axis)
  File "Miniconda3\envs\modin\lib\site-packages\pandas\core\indexing.py", line 1678, in _get_list_axis
    raise IndexError("positional indexers are out-of-bounds") from err
IndexError: positional indexers are out-of-bounds