BUG: groupby with std aggregation of pandas integer dtype throws exception: 'IntegerArray' object has no attribute 'reshape' · Issue #37415 · pandas-dev/pandas (original) (raw)

Code Sample, a copy-pastable example

import pandas as pd df = pd.DataFrame({'a': [1,1,1,2,2],'b': [1,2,3,4,5]}) df['b'] = df['b'].astype(pd.Int32Dtype()) df.groupby('a').agg('std') # Error 'IntegerArray' object has no attribute 'reshape'. The same error occurs with all pandas integer types

Problem description

For all integer pandas dtypes the code expects an IntegerArray to have the reshape function as is the case with numpy arrays.
It is possible that the error will also occur with other operations performed after a groupby, this has only been checked for 'std'.
The error occurs at
pandas\core\groupby\groupby.py", line 2491, in _get_cythonized_result
vals = vals.reshape((-1, 1))

Expected Output

The same output as with a numpy data type, for example above this would be:

a b
1 1.000000
2 0.707107

Output of pd.show_versions()

INSTALLED VERSIONS

commit : db08276
python : 3.6.9.final.0
python-bits : 64
OS : Linux
OS-release : 4.19.112+
Version : #1 SMP Thu Jul 23 08:00:38 PDT 2020
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.1.3
numpy : 1.18.5
pytz : 2018.9
dateutil : 2.8.1
pip : 19.3.1
setuptools : 50.3.0
Cython : 0.29.21
pytest : 3.6.4
hypothesis : None
sphinx : 1.8.5
blosc : None
feather : 0.4.1
xlsxwriter : None
lxml.etree : 4.2.6
html5lib : 1.0.1
pymysql : None
psycopg2 : 2.7.6.1 (dt dec pq3 ext lo64)
jinja2 : 2.11.2
IPython : 5.5.0
pandas_datareader: 0.9.0
bs4 : 4.6.3
bottleneck : 1.3.2
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : 3.2.2
numexpr : 2.7.1
odfpy : None
openpyxl : 2.5.9
pandas_gbq : 0.13.2
pyarrow : 0.14.1
pytables : None
pyxlsb : None
s3fs : None
scipy : 1.4.1
sqlalchemy : 1.3.19
tables : 3.4.4
tabulate : 0.8.7
xarray : 0.15.1
xlrd : 1.1.0
xlwt : 1.3.0
numba : 0.48.0