Finding a string in pandas.Series using the IN operator

Question

Assuming I've the following pandas.Series:

import pandas as pd
s = pd.Series([1,3,5,True,6,8,'findme', False])

I can use the in operator to find any of the integers or Booleans. Examples, the following all yield True:

1 in s
True in s

However, this fails when I do:

'findme' in s

My workaround is to use pandas.Series.str or to first convert the Series to a list and then use the in operator:

True in s.str.contains('findme')
s2 = s.tolist()
'findme' in s2

Any idea why I can't directly use the in operator to find a string in a Series?

Answer 1

Any idea why I can't directly use the in operator to find a string in a Series?

Think of a Series more like an ordered dictionary than a list-- membership testing in a Series is of the index (like keys in a dictionary), not of the values. You could access the values via under the .values attribute:

>>> s = pd.Series([1,3,5,True,6,8,'findme', False])
>>> 7 in s
True
>>> 7 in s.values
False
>>> 'findme' in s
False
>>> 'findme' in s.values
True