In [20]: df = pd.Dataframe({'A':[1,1,2,2],'B':[1,2,1,2],'values':np.arange(10,30,5)})In [21]: dfOut[21]: A B values0 1 1 101 1 2 152 2 1 203 2 2 25In [22]: df['sum_values_A'] = df.groupby('A')['values'].transform(np.sum)In [23]: dfOut[23]: A B values sum_values_A0 1 1 10 251 1 2 15 252 2 1 20 453 2 2 25 45
