Sum the values in a pandas column based on the items in another column

Question

how can I sum the values in column \'two\' based on the items in column \'one\' in pandas dataframe:

df = pd.DataFrame({\'One\': [\'A\', \'B\', \'A\', \'B\'], \'         


        

Answer 1

You need to group by the first column and sum on the second.

df.groupby('One', as_index=False).sum()

  One  Two
0   A    4
1   B    9