Retrieving count of column values based on another column value

Question

I am new to python and working on data analysis using pandas, I have a dataframe similar to one below,

col1 col2
a     10
b     20
a     30
a     15
c     10
b     10

Need to find sum of all values for col2 for each unique value in col1

Something like this:

a  55
b  30
c  10

Answer 1

df.groupby(['col1']).agg(['sum']) .. this should work

else df.groupby(['col1'])['col2'].sum()