How can i merge rows according to column name

Question

I want "an b column value" add to "other b column value" which are same "a" column values

for python ↓↓↓

Column A	Column B
title1	15
title2	12
title2	18
title3	8
title3	13
title4	7

I have this dataframe ↑

How can i transform to this one ↓

Column A	Column B
title1	15
title2	30
title3	21
title4	7

Answer 1

Solution:

Pandas has this built in functionality by combining groupby and sum together, for example

df.groupby("Column A").sum()