BUG: Adding two DataFrames together with duplicate column names in one results in infinite loop · Issue #35194 · pandas-dev/pandas (original) (raw)

Code Sample, a copy-pastable example

df1 = pd.DataFrame(data=[[0]], columns=['second']) df2 = pd.DataFrame(data=[[0, 0, 0]], columns=['first', 'second', 'second'])

Screen Shot 2020-07-09 at 3 15 10 PM

Adding them together never completes (infinite loop?)

Problem description

When adding two DataFrame where one has duplicate column names and the other has one (or more) of the duplicated columns, the operation never completes

Expected Output

Expected to follow rules of automatic alignment of the index.

Output of pd.show_versions()

INSTALLED VERSIONS

commit : None
python : 3.8.3.final.0
python-bits : 64
OS : Darwin
OS-release : 19.4.0
machine : x86_64
processor : i386
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.0.5
numpy : 1.18.5
pytz : 2020.1
dateutil : 2.8.1
pip : 20.1.1
setuptools : 47.1.1.post20200529
Cython : None
pytest : 5.4.2
hypothesis : None
sphinx : 3.1.2
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.5.1
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : 7.16.1
pandas_datareader: None
bs4 : 4.9.1
bottleneck : None
fastparquet : None
gcsfs : None
lxml.etree : 4.5.1
matplotlib : 3.2.1
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pytest : 5.4.2
pyxlsb : None
s3fs : None
scipy : 1.5.0
sqlalchemy : None
tables : None
tabulate : 0.8.7
xarray : None
xlrd : None
xlwt : None
xlsxwriter : None
numba : None