BUG: pd.DataFrame.transform recursively loops in some cases · Issue #34224 · pandas-dev/pandas (original) (raw)

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Code Sample, a copy-pastable example

pd.DataFrame({"a":[None]}).transform({"a":int})

Problem description

Executing the above causes recursion depth limit exception. This is confusing and it is harder to pinpoint/debug than the expected exception.

Expected Output

Something akin to the output of int(None)

Output of pd.show_versions()

INSTALLED VERSIONS ------------------ commit : None python : 3.7.5.final.0 python-bits : 64 OS : Darwin OS-release : 18.6.0 machine : x86_64 processor : i386 byteorder : little LC_ALL : None LANG : None LOCALE : None.UTF-8

pandas : 1.0.3
numpy : 1.18.4
pytz : 2020.1
dateutil : 2.8.1
pip : 19.2.3
setuptools : 41.2.0
Cython : None
pytest : 3.10.1
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
fastparquet : None
gcsfs : None
lxml.etree : None
matplotlib : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pytest : 3.10.1
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
xlsxwriter : None
numba : None