按每个唯一列值的最近日期过滤 Pandas 数据框

Question

I have a dataframe:

      Col1          timestamp

1    x20034   2019-11-19 14:56:51
2    x20035   2019-11-20 12:16:22
3    x20035   2019-12-09 17:47:44
4    x20037   2019-12-08 17:47:44
5    x20037   2019-12-09 18:47:44
6    x20037   2019-12-10 22:47:40

And I need:

1    x20034   2019-11-19 14:56:51
2    x20035   2019-11-20 12:16:22
6    x20037   2019-12-10 22:47:40

I tried:

df[df['timestamp'] == df['timestamp'].max()]

Is this the best/only way?

Answer 1

尝试transform

out = df[df['timestamp'] == df.groupby('Col1')['timestamp'].transform('max')]