Pandas - dataframe groupby - how to get sum of multiple columns

Question

This should be an easy one, but somehow I couldn\'t find a solution that works.

I have a pandas dataframe which looks like this:

index col1   col2            


        

Answer 1

By using apply

df.groupby(['col1', 'col2'])["col3", "col4"].apply(lambda x : x.astype(int).sum())
Out[1257]: 
           col3  col4
col1 col2            
a    c        2     4
     d        1     2
b    d        1     2
     e        2     4

If you want to agg

df.groupby(['col1', 'col2']).agg({'col3':'sum','col4':'sum'})