BUG: KeyError: '[nan] not in index' when using nan to index · Issue #52234 · pandas-dev/pandas (original) (raw)

Pandas version checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandas.
• I have confirmed this bug exists on the main branch of pandas. (tested on 2.0.0rc1, assuming that's close enough to main)

Reproducible Example

import numpy as np import pandas as pd

df = pd.DataFrame(index=pd.Index([np.nan, 100.0, 200.0, 300, 100.0])) ix = pd.Index([100, np.nan]) df.loc[ix] Traceback (most recent call last): File "", line 1, in File "venv/lib64/python3.8/site-packages/pandas/core/indexing.py", line 1073, in getitem return self._getitem_axis(maybe_callable, axis=axis) File "venv/lib64/python3.8/site-packages/pandas/core/indexing.py", line 1301, in _getitem_axis return self._getitem_iterable(key, axis=axis) File "venv/lib64/python3.8/site-packages/pandas/core/indexing.py", line 1239, in _getitem_iterable keyarr, indexer = self._get_listlike_indexer(key, axis) File "venv/lib64/python3.8/site-packages/pandas/core/indexing.py", line 1432, in _get_listlike_indexer keyarr, indexer = ax._get_indexer_strict(key, axis_name) File "venv/lib64/python3.8/site-packages/pandas/core/indexes/base.py", line 6070, in _get_indexer_strict self._raise_if_missing(keyarr, indexer, axis_name) File "venv/lib64/python3.8/site-packages/pandas/core/indexes/base.py", line 6133, in _raise_if_missing raise KeyError(f"{not_found} not in index") KeyError: '[nan] not in index'

Issue Description

I'm using a row index which can contain nan values, but I'm unable to use it to index the rows in the dataframe.

However when I try to convert the index to a mask, it seems to be working:

>>> m = df.index.isin(ix)
>>> m
array([ True,  True, False, False,  True])
>>> df[m]
Empty DataFrame
Columns: []
Index: [nan, 100.0]

Expected Behavior

returns

Empty DataFrame
Columns: []
Index: [nan, 100.0]

just like df[m] does.

Installed Versions

INSTALLED VERSIONS

commit : 2e218d1
python : 3.8.16.final.0
python-bits : 64
OS : Linux
OS-release : 6.1.18-200.fc37.x86_64
Version : #1 SMP PREEMPT_DYNAMIC Sat Mar 11 16:09:14 UTC 2023
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_AU.UTF-8
LOCALE : en_AU.UTF-8

pandas : 1.5.3
numpy : 1.23.2
pytz : 2020.4
dateutil : 2.8.1
setuptools : 59.6.0
pip : 22.2.2
Cython : 0.29.32
pytest : 7.1.2
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 0.9.6
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : 2.8.6
jinja2 : 2.11.2
IPython : None
pandas_datareader: None
bs4 : None
bottleneck : 1.3.5
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : None
numba : None
numexpr : 2.8.1
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 1.0.1
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.4.1
snappy : None
sqlalchemy : 1.3.23
tables : 3.7.0
tabulate : None
xarray : None
xlrd : 2.0.1
xlwt : None
zstandard : None
tzdata : None