Description
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I have confirmed this bug exists on the latest version of pandas.
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Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.
Code Sample, a copy-pastable example
import pandas as pd
df = pd.DataFrame({"A": [1, 2, 3]})
a = df["A"]
a += 999
print(df)
print(df["A"])
assert a is df["A"]Problem description
I expect print(df) and print(df["A"]) to show identical values for column A. This is not the case. The output of the code above:
A
0 1
1 2
2 3
0 1000
1 1001
2 1002
Name: A, dtype: int64
Expected Output
A
0 1000
1 1001
2 1002
0 1000
1 1001
2 1002
Name: A, dtype: int64
Output of pd.show_versions()
INSTALLED VERSIONS
commit : fd20f7d
python : 3.8.2.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.0-47-generic
Version : #51-Ubuntu SMP Fri Sep 4 19:50:52 UTC 2020
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 1.2.0.dev0+379.gfd20f7d34
numpy : 1.19.2
pytz : 2020.1
dateutil : 2.8.1
pip : 20.0.2
setuptools : 44.0.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : None
IPython : None
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None
None
Possibly related to #36051?