Pandas version checks
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[X] I have checked that this issue has not already been reported.
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[X] 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
import pandas as pd
df = pd.DataFrame({'A': [10, 20, 30, 40], 'B': [1, 5, 1, 5]})
df = df[df['B'] == 5]
df = df.sort_values(by='A', ignore_index=True)
df_test = pd.DataFrame({'A': [20, 40], 'B': [5, 5]})
pd.testing.assert_frame_equal(df_test, df)
# DataFrame.index values are different (100.0 %)
# [left]: RangeIndex(start=0, stop=2, step=1)
# [right]: Index([1, 3], dtype='int64')
# At positional index 0, first diff: 0 != 1
Issue Description
ignore_index used to reset the index of sorted dataframe, but since pandas>=2.0.0 index remains unchanged
Expected Behavior
reset dataframe index if sort_values is called with ignore_index=True
Installed Versions
INSTALLED VERSIONS
------------------
commit : 478d340667831908b5b4bf09a2787a11a14560c9
python : 3.11.3.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.22621
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 12, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_United States.1252
pandas : 2.0.0
numpy : 1.24.2
pytz : 2023.3
dateutil : 2.8.2
setuptools : 67.6.1
pip : 23.0.1
tzdata : 2023.3