I have a pandas dataframe, in the ID column the values are strings: 1,1,2,2,3,3,4,4,5,5, etc....
I would like to add to the string so it looks like 1.1,1.2,2.1,2.2,3.1,3.2, etc...
Ideally, if there is a third or fourth identical value then it is logically updated like 1.1, 1.2, 1.3, 1.4, etc...
How is this best achieved?
You'd have to use GroupBy.cumcount. Then use concatenate them using Series.str.cat.
# s = pd.Series(['1', '1', '2', '2', '3', '3', '4', '4', '5', '5'])
s.str.cat(s.groupby(s).cumcount().add(1).astype(str), sep='.')
# 0 1.1
# 1 1.2
# 2 2.1
# 3 2.2
# 4 3.1
# 5 3.2
# 6 4.1
# 7 4.2
# 8 5.1
# 9 5.2
# dtype: object