Check if string is in a pandas dataframe

Question

I would like to see if a particular string exists in a particular column within my dataframe.

I'm getting the error

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

import pandas as pd  BabyDataSet = [('Bob', 968), ('Jessica', 155), ('Mary', 77), ('John', 578), ('Mel', 973)]  a = pd.DataFrame(data=BabyDataSet, columns=['Names', 'Births'])  if a['Names'].str.contains('Mel'):     print ("Mel is there") 

Answer 1

a['Names'].str.contains('Mel') will return an indicator vector of boolean values of size len(BabyDataSet)

Therefore, you can use

mel_count=a['Names'].str.contains('Mel').sum() if mel_count>0:     print ("There are {m} Mels".format(m=mel_count)) 

Or any(), if you don't care how many records match your query

if a['Names'].str.contains('Mel').any():     print ("Mel is there") 

Answer 2

You should use any()

In [98]: a['Names'].str.contains('Mel').any() Out[98]: True  In [99]: if a['Names'].str.contains('Mel').any():    ....:     print "Mel is there"    ....: Mel is there 

a['Names'].str.contains('Mel') gives you a series of bool values

In [100]: a['Names'].str.contains('Mel') Out[100]: 0    False 1    False 2    False 3    False 4     True Name: Names, dtype: bool