Pandas Groupby Rank Date Time

i got an issue over ranking of date times. Lets say i have following table. ID TIME 01 2018-07-11 11:12:20 01 2018-07-12 12:00:23 01 2018-07-13 12:00:00 02 2019-09-1

Solution 1:

For me working convert column to datetimes for avoid your error.

data['TIME'] = pd.to_datetime(data['TIME'])
data['RANK'] = data.groupby('ID')['TIME'].rank(ascending=True)
print (data)
   ID                TIME  RANK
0   1 2018-07-11 11:12:20   1.0
1   1 2018-07-12 12:00:23   2.0
2   1 2018-07-13 12:00:00   3.0
3   2 2019-09-11 11:00:00   1.0
4   2 2019-09-12 12:00:00   2.0