Pandas groupby cumulative count

Question

How do I do a cumcount on two groupings, id and name? For example I have:

id  name
1   name1
1   name1
1   name2
2   name3
2   name3
2   name3

Answer 1

You can use groupby.cumcount:

df['cumcount'] = df.groupby(['id', 'name']).cumcount() + 1

df
#  id   name    cumcount
#0  1   name1   1
#1  1   name1   2
#2  1   name2   1
#3  2   name3   1
#4  2   name3   2
#5  2   name3   3