How to group values of pandas dataframe and select the latest(by date) from each group?
For example, given a dataframe sorted by date:
id product date
0 220 6647 2014-09-01
1 220 6647 2014-09-03
2 220 6647 2014-10-16
3 826 3380 2014-11-11
4 826 3380 2014-12-09
5 826 3380 2015-05-19
6 901 4555 2014-09-01
7 901 4555 2014-10-05
8 901 4555 2014-11-01
grouping by id or product, and selecting the earliest gives:
id product date
2 220 6647 2014-10-16
5 826 3380 2015-05-19
8 901 4555 2014-11-01
You can also use tail
with groupby to get the last n values of the group:
df.sort_values('date').groupby('id').tail(1)
id product date
2 220 6647 2014-10-16
8 901 4555 2014-11-01
5 826 3380 2015-05-19