Suppose I have a dataframe df looking like school score student_id 0 1 100.0 965 1 2 64.0 1483 2 2 100.0 1055 3 2 68.0 1806 4 1 100.0 971 I want to find how many maximum scores in each group and get something like this: school count_max 1 2 2 1 How can I do it? Continue reading...