时间计算 pandas

Question

我需要计算时间差，然后从第一行开始分配结果。这是我的代码：

import pandas as pd

dtime = pd.DataFrame({'letter': ['a', 'b', 'c', 'd', 'e', 'f'], 'time': ['19/11/2019  06:02:39', '19/11/2019  06:32:39', '2019-11-19 06:42:39' , '19/11/2019  06:52:39', '19/11/2019  07:02:39', '19/11/2019  07:12:39']})
dtime['time'] = pd.to_datetime(dtime['time'])

dtime['Time_diff']=(dtime['time']-dtime['time'].shift()).fillna(0)
print (dtime)
dtime.to_excel('test_time.xlsx', 'Sheet1', index=True)

这是输出：

  letter                time Time_diff
0      a 2019-11-19 06:02:39  00:00:00
1      b 2019-11-19 06:32:39  00:30:00
2      c 2019-11-19 06:42:39  00:10:00
3      d 2019-11-19 06:52:39  00:10:00
4      e 2019-11-19 07:02:39  00:10:00
5      f 2019-11-19 07:12:39  00:10:00

但我需要这样：

  letter                time Time_diff
0      a 2019-11-19 06:02:39  00:30:00
1      b 2019-11-19 06:32:39  00:10:00
2      c 2019-11-19 06:42:39  00:10:00
3      d 2019-11-19 06:52:39  00:10:00
4      e 2019-11-19 07:02:39  00:10:00
5      f 2019-11-19 07:12:39  00:00:00

行 0: 0 一个 2019-11-19 06:02:39 00:30:00

有可能吗？？

Answer 1

更改顺序并将 -1 添加到 Series.shift，也可以使用 0 timedelta:

替换缺失值

dtime['Time_diff']=(dtime['time'].shift(-1)-time['time']).fillna(pd.Timedelta(0))
print (dtime)
  letter                time Time_diff
0      a 2019-11-19 06:02:39  00:30:00
1      b 2019-11-19 06:32:39  00:10:00
2      c 2019-11-19 06:42:39  00:10:00
3      d 2019-11-19 06:52:39  00:10:00
4      e 2019-11-19 07:02:39  00:10:00
5      f 2019-11-19 07:12:39  00:00:00

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