Description
Pandas version checks
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I have checked that this issue has not already been reported.
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I have confirmed this bug exists on the latest version of pandas.
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I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
>>> df = pd.DataFrame({'a': [True, True, False, False], 'b': [True, False, True, False], 'c': [1,2,3,4]})
>>> df
a b c
0 True True 1
1 True False 2
2 False True 3
3 False False 4
>>> df.set_index(['a']).loc[True]
b c
a
True True 1
True False 2
>>> df.set_index(['a', 'b']).loc[True]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/kale/hacking/forks/pandas/pandas/core/indexing.py", line 1071, in __getitem__
return self._getitem_axis(maybe_callable, axis=axis)
File "/home/kale/hacking/forks/pandas/pandas/core/indexing.py", line 1306, in _getitem_axis
self._validate_key(key, axis)
File "/home/kale/hacking/forks/pandas/pandas/core/indexing.py", line 1116, in _validate_key
raise KeyError(
KeyError: 'True: boolean label can not be used without a boolean index'Issue Description
The above snippet creates a data frame with two boolean columns. When just one of those columns is set as the index, .loc[] can select rows based on a boolean value. When both columns are set as the index, though, the same value causes .loc[] to raise a KeyError. The error message makes it seems like pandas doesn't regard a multi-index as a "boolean index", even if the columns making up the index are all boolean.
In pandas 1.4.3, I can work around this by indexing with 1 and 0 instead of True and False. But in 1.5.0 it seems to be an error to provide a integer value to a boolean index.
Expected Behavior
I would expect to be able to use boolean index values even when those values are part of a multi-index:
>>> df.set_index(['a', 'b']).loc[True]
c
b
True 1
False 2
Installed Versions
pandas : 1.5.0.dev0+1134.g74f4e81ca8
numpy : 1.22.0
pytz : 2021.3
dateutil : 2.8.2
setuptools : 57.4.0
pip : 22.1.2
Cython : 0.29.30
pytest : 7.1.1
hypothesis : 6.39.4
sphinx : 4.3.2
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.8.0
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.0.3
IPython : 8.0.1
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.5.1
numba : None
numexpr : None
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.8.0
snappy : None
sqlalchemy : 1.4.31
tables : None
tabulate : 0.8.9
xarray : None
xlrd : None
xlwt : None
zstandard : None