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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.
import pandas as pd df_one=pd.DataFrame({'A':['a','b'],'B':[1,2]}) df_two=pd.DataFrame({'A':['b','c'],'B':[3,4]}) df_one.columns=pd.MultiIndex.from_product([['one'],df_one.columns]) df_two.columns=pd.MultiIndex.from_product([['two'],df_two.columns]) df=pd.merge(df_one,df_two,how='outer',left_on=[('one','A')],right_on=[('two','A')],indicator=True)
When merging two dataframes with multiindex columns, if indicator is set to True, pandas shows:
PerformanceWarning: dropping on a non-lexsorted multi-index without a level parameter may impact performance.
If indicator is set to False, no warning is shown.
The expected behavior would be the execution of the code without the warning.
pandas : 1.5.1 numpy : 1.22.4 pytz : 2022.5 dateutil : 2.8.2 setuptools : 65.3.0 pip : 22.2.2 Cython : 0.29.32 pytest : 7.1.3 hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : 4.9.1 html5lib : None pymysql : None psycopg2 : None jinja2 : 3.1.2 IPython : 8.5.0 pandas_datareader: None bs4 : 4.11.1 bottleneck : 1.3.5 brotli : fastparquet : None fsspec : 2022.10.0 gcsfs : None matplotlib : 3.6.0 numba : 0.55.2 numexpr : 2.8.3 odfpy : None openpyxl : None pandas_gbq : None pyarrow : None pyreadstat : None pyxlsb : None s3fs : None scipy : 1.9.1 snappy : None sqlalchemy : 1.4.41 tables : 3.7.0 tabulate : None xarray : 2022.10.0 xlrd : 2.0.1 xlwt : None zstandard : None tzdata : None
The text was updated successfully, but these errors were encountered:
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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
Issue Description
When merging two dataframes with multiindex columns, if indicator is set to True, pandas shows:
If indicator is set to False, no warning is shown.
Expected Behavior
The expected behavior would be the execution of the code without the warning.
Installed Versions
pandas : 1.5.1
numpy : 1.22.4
pytz : 2022.5
dateutil : 2.8.2
setuptools : 65.3.0
pip : 22.2.2
Cython : 0.29.32
pytest : 7.1.3
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.9.1
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.5.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : 1.3.5
brotli :
fastparquet : None
fsspec : 2022.10.0
gcsfs : None
matplotlib : 3.6.0
numba : 0.55.2
numexpr : 2.8.3
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.9.1
snappy : None
sqlalchemy : 1.4.41
tables : 3.7.0
tabulate : None
xarray : 2022.10.0
xlrd : 2.0.1
xlwt : None
zstandard : None
tzdata : None
The text was updated successfully, but these errors were encountered: