groupby counter of rows

Question

I am trying to create a new variable which counts how many times had been seen the same id over time.

Need to pass from this dataframe

   id     clae6  y         


        

Answer 1

By using cumcount

df.groupby('id').cumcount().add(1)
Out[1574]: 
0     1
1     2
2     3
3     4
4     5
5     6
6     1
7     2
8     3
9     4
10    5
11    1
12    2
13    3
14    4
dtype: int64