Pandas version checks

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  • [ ] I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd

df = pd.DataFrame({'numbers': [1, 2], 'strings': ['hello', 'goodbye']})
mask_nulls = pd.DataFrame({'numbers': [True, False], 'strings': [False, True]})

df.mask(mask_nulls, inplace=True)

# Traceback (most recent call last):
#   File "<stdin>", line 1, in <module>
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/frame.py", line 11554, in mask
#     return super().mask(
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/generic.py", line 9961, in mask
#     return self.where(
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/frame.py", line 11501, in where
#     return super().where(
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/generic.py", line 9899, in where
#     return self._where(cond, other, inplace, axis, level)
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/generic.py", line 9695, in _where
#     self._check_inplace_setting(other)
#   File "/home/eugenio/workspace/pandastest/200rc0/.venv/lib/python3.9/site-packages/pandas/core/generic.py", line 6087, in _check_inplace_setting
#     raise TypeError(
# TypeError: Cannot do inplace boolean setting on mixed-types with a non np.nan value

Issue Description

The reasons I believe this is a bug in 2.0.0rc0 are: - If you remove the inplace=True from the pd.DataFrame.mask invocation, it works. Same behavior, except for the result being in a copy of course. - In Pandas 1.5.4 this does not happen, i.e. both inplace=True and inplace=False work properly. - Inplace mask works if you pass other=np.nan, which is strange.

Perhaps the behavior of the inplace masking in 2.0.0rc0 is correct, in which case I believe the inplace=False case should be consistent with it and equally fail.

Expected Behavior

The df DataFrame should look like the following, after the inplace masking. Just like it did in Pandas 1.5.4, or like it does in Pandas 2.0.0rc0 with inplace=False.

>>> df
   numbers strings
0      NaN   hello
1      2.0     NaN

Thanks for all the great work on Pandas! And apologies if this is duplicated or not an issue (and a misuse of the library on my part), this is my first opened issue on the repository.

Installed Versions

INSTALLED VERSIONS ------------------ commit : 1a2e300170efc08cb509a0b4ff6248f8d55ae777 python : 3.9.12.final.0 python-bits : 64 OS : Linux OS-release : 5.19.0-32-generic Version : #33~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Jan 30 17:03:34 UTC 2 machine : x86_64 processor : x86_64 byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : en_US.UTF-8 pandas : 2.0.0rc0 numpy : 1.24.2 pytz : 2022.7.1 dateutil : 2.8.2 setuptools : 58.1.0 pip : 23.0.1 Cython : None pytest : None hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : None html5lib : None pymysql : None psycopg2 : None jinja2 : None IPython : None pandas_datareader: None bs4 : None bottleneck : None brotli : None fastparquet : None fsspec : None gcsfs : None matplotlib : None numba : None numexpr : None odfpy : None openpyxl : None pandas_gbq : None pyarrow : None pyreadstat : None pyxlsb : None s3fs : None scipy : None snappy : None sqlalchemy : None tables : None tabulate : None xarray : None xlrd : None zstandard : None tzdata : None qtpy : None pyqt5 : None

Comment From: asishm

Possibly due to https://github.com/pandas-dev/pandas/pull/49156 that changed the default from np.nan to lib.no_default

specifying other=np.nan works without issues i.e. df.mask(mask_nulls, np.nan inplace=True)

Comment From: phofl

Yep can confirm

commit a75ea75a0d4efaf273ac70b6269adbfa400d0844
Author: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date:   Tue Oct 18 02:22:40 2022 -0700

    API: Change Series/DataFrame.other default to no_default instead of np.nan (#49156)

cc @mroeschke