mdf = pd.DataFrame([[1,2,50],[1,2,30],[1,5,10],[2,8,80]], columns=['src','dst','n']); mdf

    src dst n
0   1   2   50
1   1   2   30
2   1   5   10
3   2   8   80

test = mdf.groupby(['src','dst'])['n'].agg(['sum','count']); test


        sum count
src dst
1   2   80  2
    5   10  1
2   8   80  1