Python Pandas - Caveats & Gotchas

Caveats means warning and gotcha means an unseen problem.

Using If/Truth Statement with Pandas:

Pandas follows the numpy convention of raising an error when you try to convert something to a bool . This happens in an if  or when  using the Boolean operations, and, or , or not . It is not clear what the result should be. Should it be True because it is not zerolength? False because there are False values? It is unclear, so instead, Pandas raises a ValueError  –

import pandas as pd

if pd. Series ([ False , True , False ]):

   print 'I am True'

Its output is as follows −

ValueError: The truth value of a Series is ambiguous.

Use a.empty, a.bool() a.item(),a.any() or a.all().