python - Pandas 将数据重新采样到秒，每约 10 秒进行分组

Question

假设我有以下数据框:

>>> df
                       a
2019-04-05 00:00:00  2.0                
2019-04-05 00:00:01  1.0
2019-04-05 00:00:02  NaN
2019-04-05 00:00:03  NaN
2019-04-05 00:00:04  NaN
2019-04-05 00:00:05  NaN
2019-04-05 00:00:06  NaN
2019-04-05 00:00:07  NaN
2019-04-05 00:00:08  3.0
2019-04-05 00:00:09  4.0
2019-04-05 00:00:10  NaN
2019-04-05 00:00:11  NaN
2019-04-05 00:00:12  NaN
2019-04-05 00:00:13  NaN
2019-04-05 00:00:14  NaN
2019-04-05 00:00:15  NaN
2019-04-05 00:00:16  NaN
2019-04-05 00:00:17  NaN
2019-04-05 00:00:18  NaN
2019-04-05 00:00:19  NaN
2019-04-05 00:00:20  4.0
2019-04-05 00:00:21  5.0
2019-04-05 00:00:22  NaN
2019-04-05 00:00:23  NaN
2019-04-05 00:00:24  NaN
2019-04-05 00:00:25  NaN
2019-04-05 00:00:26  6.0
2019-04-05 00:00:27  NaN
2019-04-05 00:00:28  4.0
2019-04-05 00:00:29  NaN
2019-04-05 00:00:30  NaN
2019-04-05 00:00:31  NaN

我希望每 7 秒有 1 个值(假设有一个值，否则只是一个 NaN)，因此数据框如下所示:

>>> df
                       a
2019-04-05 00:00:00  2.0                
2019-04-05 00:00:01  NaN
2019-04-05 00:00:02  NaN
2019-04-05 00:00:03  NaN
2019-04-05 00:00:04  NaN
2019-04-05 00:00:05  NaN
2019-04-05 00:00:06  NaN
2019-04-05 00:00:07  NaN
2019-04-05 00:00:08  3.0
2019-04-05 00:00:09  NaN
2019-04-05 00:00:10  NaN
2019-04-05 00:00:11  NaN
2019-04-05 00:00:12  NaN
2019-04-05 00:00:13  NaN
2019-04-05 00:00:14  NaN
2019-04-05 00:00:15  NaN
2019-04-05 00:00:16  NaN
2019-04-05 00:00:17  NaN
2019-04-05 00:00:18  NaN
2019-04-05 00:00:19  NaN
2019-04-05 00:00:20  4.0
2019-04-05 00:00:21  NaN
2019-04-05 00:00:22  NaN
2019-04-05 00:00:23  NaN
2019-04-05 00:00:24  NaN
2019-04-05 00:00:25  NaN
2019-04-05 00:00:26  NaN
2019-04-05 00:00:27  NaN
2019-04-05 00:00:28  4.0
2019-04-05 00:00:29  NaN
2019-04-05 00:00:30  NaN
2019-04-05 00:00:31  NaN

7 秒点是任意的，实际上我大约每分钟都会取值。这是我到目前为止所尝试过的:

df = df.resample('7s').first()

但这会产生以下数据帧:

                       a
2019-04-05 00:00:00  2.0
2019-04-05 00:00:07  3.0
2019-04-05 00:00:14  4.0
2019-04-05 00:00:21  5.0
2019-04-05 00:00:28  4.0

注意:我并不为这些点之间缺少 NaN 所困扰，因为它们是隐含的。我只是对时间不满意，因为它每 7 秒强制一个值，而我只想不允许值彼此相差在 7 秒内，而不需要每 7 秒一个值。

为清楚起见，伊迪丝:

我不想要的数据帧:

                       a
2019-04-05 00:00:00  2.0
2019-04-05 00:00:07  3.0
2019-04-05 00:00:14  4.0
2019-04-05 00:00:21  5.0
2019-04-05 00:00:28  4.0

我想要的数据框:

>>> df
                       a
2019-04-05 00:00:00  2.0                
2019-04-05 00:00:01  NaN
2019-04-05 00:00:02  NaN
2019-04-05 00:00:03  NaN
2019-04-05 00:00:04  NaN
2019-04-05 00:00:05  NaN
2019-04-05 00:00:06  NaN
2019-04-05 00:00:07  NaN
2019-04-05 00:00:08  3.0
2019-04-05 00:00:09  NaN
2019-04-05 00:00:10  NaN
2019-04-05 00:00:11  NaN
2019-04-05 00:00:12  NaN
2019-04-05 00:00:13  NaN
2019-04-05 00:00:14  NaN
2019-04-05 00:00:15  NaN
2019-04-05 00:00:16  NaN
2019-04-05 00:00:17  NaN
2019-04-05 00:00:18  NaN
2019-04-05 00:00:19  NaN
2019-04-05 00:00:20  4.0
2019-04-05 00:00:21  NaN
2019-04-05 00:00:22  NaN
2019-04-05 00:00:23  NaN
2019-04-05 00:00:24  NaN
2019-04-05 00:00:25  NaN
2019-04-05 00:00:26  NaN
2019-04-05 00:00:27  NaN
2019-04-05 00:00:28  4.0
2019-04-05 00:00:29  NaN
2019-04-05 00:00:30  NaN
2019-04-05 00:00:31  NaN

或者:

>>> df
                       a
2019-04-05 00:00:00  2.0
2019-04-05 00:00:08  3.0
2019-04-05 00:00:20  4.0
2019-04-05 00:00:28  4.0

Answer 1

您可以对数据帧进行上采样，您已经非常接近了；

df = df.resample('7s').first()
df = df.resample(rule='1s')

这将为新插入的行在添加的秒数上创建一个包含 NaN 的数据框。