按每個唯一列值的最近日期過濾 Pandas 數據框

Question

我有一個數據框：

      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

我需要：

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

我試過：

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

這是最好的/唯一的方法嗎？

Answer 1

嘗試transform

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