根据熊猫中列的唯一分组对数据框值求和

Question

i want to aggregate values from this pandas table after grouping by name :

name  id  c   
john  a1  10  
john  a1  10
bob   a2  20
mary  a3  30

specifically i want to sum the values of c , grouped by name , but only for instances where id is unique. df.groupby(["id"]).agg({"c": np.sum}) is not right because the two a1 entries would have their c values summed. i want only unique values of id to contribute to the sum of c values. how can you write this in pandas?

Answer 1

This should work.

df.drop_duplicates(['name', 'id'], keep='first', inplace=True)
df = df.groupby('name').sum().reset_index()