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

The above answer didn't work for me.

df_new = df.groupby(['col1', 'col2']).sum()[["col3", "col4"]]

I was grouping by single group by and sum columns.

Here is the one worked for me.

D1.groupby(['col1'])['col2'].sum() << The sum at the end not the middle.