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

User · Accepted Answer

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 gt 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

User · Answer

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

User · Answer

it seems that the OP meant to find out whether the string  Mel  exists in a particular column  not contained in a column  therefore the use of contains is not needed  and is not efficient  A simple equals-to is enough    a  Names     Mel   any

User · Answer

If there is any chance that you will need to search for empty strings        a  Names   str contains        will NOT work  as it will always return True   Instead  use      if    in a  Names   values   to accurately reflect whether or not a string is in a Series  including the edge case of searching for an empty string

User · Answer

I bumped into the same problem  I used   if  Mel  in a  Names   values      print  Yep     But this solution may be slower since internally pandas create a list from a Series

User · Answer

Pandas seem to be recommending df to numpy since the other methods still raise a FutureWarning  https   pandas pydata org pandas-docs stable reference api pandas DataFrame to numpy html pandas DataFrame to numpy So  an alternative that would work int this case is  b a  Names   c   b to numpy   tolist   if  Mel  in c       print  quot Mel is in the dataframe column Names quot

User · Answer

You should check the value of your line of code like adding checking length of it   if len a  Names   str contains  Mel    gt 0       print  Name Present

[python] Check if string is in a pandas dataframe

Examples related to python

Examples related to python-2.7

Examples related to pandas