Bonswouar Bonswouar - 1 month ago 10
Python Question

How to find out where a Python Warning is from

I'm still kinda new with Python, using Pandas, and I've got some issues debugging my Python script.

I've got the following warning message :

[...]\pandas\core\index.py:756: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
return self._engine.get_loc(key)


And can't find where it's from.

After some research, I tried to do that in the Pandas lib file (index.py):

try:
return self._engine.get_loc(key)
except UnicodeWarning:
warnings.warn('Oh Non', stacklevel=2)


But that didn't change anything about the warning message.

Answer

You can filter the warnings to raise which will enable you to debug (e.g. using pdb):

import warnings
warnings.filterwarnings('error')

*The warnings filter can be managed more finely (which is probably more appropriate) e.g.:

warnings.filterwarnings('error', category=UnicodeWarning)
warnings.filterwarnings('error', message='*equal comparison failed*')

Multiple filters will be looked up sequentially. ("Entries closer to the front of the list override entries later in the list, if both match a particular warning.")

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