Python 如何从时间增量列表中选择数据

我有一张这样的清单。我想知道如何才能找出时间差小于21天的条目，并且我想将索引保留为machine_id

machine_id
13512886     0 days 00:00:00
49645796     0 days 00:00:00
58622574     0 days 00:00:00
59850911   147 days 01:57:40
61433282     0 days 00:00:00
61538672   135 days 23:25:24
61755561   259 days 05:49:49
61876734   259 days 21:00:28
61950006   180 days 04:42:39
62508680    59 days 06:45:46
62549967     0 days 00:00:00
62643307     0 days 00:00:00
62678486     0 days 00:00:00
63761469     0 days 00:00:00
64092088     0 days 00:00:00
64194930     0 days 00:00:00
64543161     0 days 00:00:00
64720467    75 days 01:11:00
65034386     4 days 02:16:30
65118059     0 days 00:00:00
65198554     0 days 00:00:00
65347738     0 days 00:00:00
65524977     0 days 00:00:00
65556861     0 days 00:00:00
                  ...       

95318844     0 days 00:00:00
95318910     0 days 00:00:00
95319088     0 days 00:00:00
95319234   211 days 22:15:05
95319894   163 days 20:18:56
95320067     0 days 00:00:00
Name: event_datetime, Length: 3984, dtype: timedelta64[ns]

系列[系列

如果这是一个数据帧

df.loc[df['event_datetime']

否则@Rohit Raj解决方案就可以了

series[series < pd.Timedelta(days=21)]