BUG: pd.Series.rename does not return None with inplace=True

[Omerdan03]

• [ X] I have checked that this issue has not already been reported.

• [ X] I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

---

Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

ser = pd.Series([1,2,3], name='ser1')
f = ser.rename('ser2', inplace=True)

Problem description

f should be None like other inplace functionality.
instead f is Series object.

[this should explain why the current behaviour is a problem and why the expected output is a better solution]

Expected Output

Output of pd.show_versions()

INSTALLED VERSIONS

commit : b5958ee
python : 3.6.10.final.0
python-bits : 64
OS : Linux
OS-release : 5.8.0-59-generic
Version : #66~20.04.1-Ubuntu SMP Thu Jun 17 11:14:10 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.1.5
numpy : 1.19.5
pytz : 2021.1
dateutil : 2.8.1
pip : 21.0.1
setuptools : 52.0.0.post20210125
Cython : None
pytest : 6.2.3
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 1.3.9
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.3
IPython : 7.16.1
pandas_datareader: None
bs4 : 4.9.3
bottleneck : None
fsspec : 0.9.0
fastparquet : None
gcsfs : None
matplotlib : 3.3.4
numexpr : 2.7.3
odfpy : None
openpyxl : 3.0.6
pandas_gbq : None
pyarrow : None
pytables : None
pyxlsb : None
s3fs : None
scipy : 1.5.4
sqlalchemy : None
tables : 3.6.1
tabulate : None
xarray : None
xlrd : 1.2.0
xlwt : 1.3.0
numba : 0.53.1

[Omerdan03]

[mzeitlin11]

Thanks for reporting this @Omerdan03! If you (or anyone else) is interested in contributing a fix, looks like the issue is here:

pandas/pandas/core/series.py

Lines 1750 to 1763 in 844b388

	def _set_name(self, name, inplace=False) -> Series:
	"""
	Set the Series name.
	Parameters
	----------
	name : str
	inplace : bool
	Whether to modify `self` directly or return a copy.
	"""
	inplace = validate_bool_kwarg(inplace, "inplace")
	ser = self if inplace else self.copy()
	ser.name = name
	return ser

Hopefully just returning ser only if inplace=False would fix this and not break anything else

[Gdango]

Hello, I am new here. I would like to contribute to this issue.

[mzeitlin11]

Hello, I am new here. I would like to contribute to this issue.

Looks like someone already put up a pr, please feel free to contribute to any other issues! (filtering by good first issue is also a good way to find good issues to start with)

[jbrockmendel]

Duplicate of #28920?

[jbrockmendel]

Closing as duplicate of #28920