pandas-dev
BUG: None value converted to NaN in Series
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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[X] I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
>>> import pandas as pd
>>> s = pd.Series(['a', 'b'])
>>> s
0 a
1 b
dtype: object
>>> s['a'] = None
>>> s
0 a
1 b
a NaN
dtype: object
Issue Description
In 1.5.0 there is a behaviour change, if you set a value on a Serie to None it is replaced with NaN.
Same thing with s.loc['dd'] = None
Expected Behavior
It should stay None
Installed Versions
INSTALLED VERSIONS
commit : 9a607e2afa549a9295db09ad05df6572c1a85542 python : 3.8.13.final.0 python-bits : 64 OS : Darwin OS-release : 21.6.0 Version : Darwin Kernel Version 21.6.0: Wed Aug 10 14:25:27 PDT 2022; root:xnu-8020.141.5~2/RELEASE_X86_64 machine : x86_64 processor : i386 byteorder : little LC_ALL : None LANG : en_GB.UTF-8 LOCALE : en_GB.UTF-8
pandas : 1.6.0.dev0+165.g9a607e2afa numpy : 1.22.3 pytz : 2021.3 dateutil : 2.8.2 setuptools : 56.0.0 pip : 22.0.4 Cython : 0.29.32 pytest : 6.2.5 hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : None html5lib : 1.1 pymysql : None psycopg2 : None jinja2 : 3.0.3 IPython : 7.16.1 pandas_datareader: None bs4 : 4.11.1 bottleneck : None brotli : None fastparquet : None fsspec : 0.8.7 gcsfs : None matplotlib : 3.5.1 numba : None numexpr : None odfpy : None openpyxl : None pandas_gbq : None pyarrow : 3.0.0 pyreadstat : None pyxlsb : None s3fs : 0.3.5 scipy : 1.5.4 snappy : None sqlalchemy : 1.4.32 tables : None tabulate : 0.8.9 xarray : None xlrd : None xlwt : None zstandard : None tzdata : None
Can confirm (as I expected :))
commit bd9a6f09264c58ef402d4c7faf5fc9d48c159194
Author: Patrick Hoefler <[email protected]>
Date: Sat Jul 2 00:18:05 2022 +0200
BUG: Series.setitem losing precision when enlarging (#47342)
I'll look into this
