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
import pandas as pd
pd.__version__
df = pd.DataFrame({"x": [1, 2, 2, 3, 3], "y": [10, 20, 30, 40, 50]})
gb = df.groupby("x")["y"]
gb.nth(0)Issue Description
With the development version, you get:
'2.0.0.dev0+643.ge41b6d7827'
0 10
1 20
3 40
Name: y, dtype: int64
With pandas 1.5.1, you get:
x
1 10
2 20
3 40
Name: y, dtype: int64
Expected Behavior
Should be the 1.5.1 behavior.
Note that the index name is missing as well as the values shown for the index don't correspond to the group values (i.e., the values of 'x'
Installed Versions
INSTALLED VERSIONS
commit : e41b6d7
python : 3.8.13.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19043
machine : AMD64
processor : Intel64 Family 6 Model 158 Stepping 13, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_United States.1252
pandas : 2.0.0.dev0+643.ge41b6d7827
numpy : 1.23.3
pytz : 2022.4
dateutil : 2.8.2
setuptools : 65.4.1
pip : 22.2.2
Cython : 0.29.32
pytest : 7.1.3
hypothesis : 6.56.0
sphinx : 4.5.0
blosc : None
feather : None
xlsxwriter : 3.0.3
lxml.etree : 4.9.1
html5lib : 1.1
pymysql : 1.0.2
psycopg2 : 2.9.3
jinja2 : 3.0.3
IPython : 8.5.0
pandas_datareader: 0.10.0
bs4 : 4.11.1
bottleneck : 1.3.5
brotli :
fastparquet : 0.8.3
fsspec : 2021.11.0
gcsfs : 2021.11.0
matplotlib : 3.6.0
numba : 0.56.2
numexpr : 2.8.0
odfpy : None
openpyxl : 3.0.10
pandas_gbq : 0.17.8
pyarrow : 9.0.0
pyreadstat : 1.1.9
pyxlsb : 1.0.9
s3fs : 2021.11.0
scipy : 1.9.1
snappy :
sqlalchemy : 1.4.41
tables : 3.7.0
tabulate : 0.8.10
xarray : 2022.9.0
xlrd : 2.0.1
zstandard : 0.18.0
tzdata : None
qtpy : None
pyqt5 : None