In [1]:

    

import pandas as pd


    

In [2]:

    

df = pd.DataFrame([['One', 'Two'], ['Four', 'Abcd'], ['One', 'Bcd'], ['Five', 'Cd']], columns=['A', 'B'])


    

In [3]:

    

df


    

    
Out[3]:






  

    

      

      
A
      
B
    
  
  

    

      
0
      
One
      
Two
    
    

      
1
      
Four
      
Abcd
    
    

      
2
      
One
      
Bcd
    
    

      
3
      
Five
      
Cd
    
  

In [4]:

    

df.loc[df['A'] == 'One', 'A'] = 0


    

In [5]:

    

df


    

    
Out[5]:






  

    

      

      
A
      
B
    
  
  

    

      
0
      
0
      
Two
    
    

      
1
      
Four
      
Abcd
    
    

      
2
      
0
      
Bcd
    
    

      
3
      
Five
      
Cd
    
  

In [ ]: