Description
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.
Reproducible Example
import pandas as pd
df = pd.DataFrame(index=[1, 1, 2, 2], data=["1", "1", "2", "2"])
df.loc[df[0].str.len() > 1, 0] = df[0]
dfIssue Description
Given code fails on the third line with exception given below
Code executes normally with panda versions <2.1.0
Traceback (most recent call last):
File "", line 3, in
File "C:\Users\venv\lib\site-packages\pandas\core\indexing.py", line 885, in setitem
iloc._setitem_with_indexer(indexer, value, self.name)
File "C:\Users\venv\lib\site-packages\pandas\core\indexing.py", line 1888, in _setitem_with_indexer
indexer, value = self._maybe_mask_setitem_value(indexer, value)
File "C:\Users\venv\lib\site-packages\pandas\core\indexing.py", line 789, in _maybe_mask_setitem_value
value = self.obj.iloc._align_series(indexer, value)
File "C:\Users\venv\lib\site-packages\pandas\core\indexing.py", line 2340, in _align_series
return ser.reindex(new_ix)._values
File "C:\Users\venv\lib\site-packages\pandas\core\series.py", line 4982, in reindex
return super().reindex(
File "C:\Users\venv\lib\site-packages\pandas\core\generic.py", line 5521, in reindex
return self._reindex_axes(
File "C:\Users\venv\lib\site-packages\pandas\core\generic.py", line 5544, in _reindex_axes
new_index, indexer = ax.reindex(
File "C:\Users\venv\lib\site-packages\pandas\core\indexes\base.py", line 4433, in reindex
raise ValueError("cannot reindex on an axis with duplicate labels")
ValueError: cannot reindex on an axis with duplicate labels
Expected Behavior
Code should execute normally with result
0
1 1
1 1
2 2
2 2
(No reindexing should be necessary since no rows are selected with code on line 3.)
Installed Versions
INSTALLED VERSIONS
commit : ba1cccd
python : 3.9.0.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19041
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 12, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_Ireland.1252
pandas : 2.1.0
numpy : 1.24.2
pytz : 2023.3
dateutil : 2.8.2
setuptools : 65.5.1
pip : 22.3.1
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
dataframe-api-compat: None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : 3.1.2
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
zstandard : None
tzdata : 2023.3
qtpy : None
pyqt5 : None