How to add string to all values in a column of pandas DataFrame

Question

Say you have a DataFrame with columns;

 col_1    col_2 
   1        a
   2        b
   3        c
   4        d
   5        e

how would you change the values of col_2 so that, new value = current value + 'new'

Solution

Use +:

df.col_2 = df.col_2 + 'new'
print (df)
   col_1 col_2
0      1  anew
1      2  bnew
2      3  cnew
3      4  dnew
4      5  enew

Thanks hooy for another solution:

df.col_2 += 'new'

Or assign:

df = df.assign(col_2 = df.col_2 + 'new')
print (df)
   col_1 col_2
0      1  anew
1      2  bnew
2      3  cnew
3      4  dnew
4      5  enew

Comments

[mystery man]

@jezrael it says that the df has no attribute to assign, and using + doesnt work either. Is there a way to do it through a loop? i.e : for i in df['col2']: .... i+'new'

[jezrael]

What is df.info() ? Maybe need alternative with [] like df['col_2'] = df['col_2'] + 'new'