Pandas TimeSeries重采样产生NaN

Question

我正在重新取样Pandas TimeSeries.时间序列由二进制值(它是一个分类变量)组成,没有缺失值,但在重新采样之后会出现NaN.这怎么可能？

我不能在这里发布任何示例数据,因为它是敏感信息,但我创建并重新采样系列如下:

series = pd.Series(data, ts)
series_rs = series.resample('60T', how='mean')

Answer 1

upsampling转换为常规时间间隔,因此如果没有样本NaN.

您可以向前fill_method='bfill'或向前填充缺失值- fill_method='ffill'或 fill_method='pad'.

import pandas as pd

ts = pd.date_range('1/1/2015', periods=10, freq='100T')
data = range(10)
series = pd.Series(data, ts)
print series
#2015-01-01 00:00:00    0
#2015-01-01 01:40:00    1
#2015-01-01 03:20:00    2
#2015-01-01 05:00:00    3
#2015-01-01 06:40:00    4
#2015-01-01 08:20:00    5
#2015-01-01 10:00:00    6
#2015-01-01 11:40:00    7
#2015-01-01 13:20:00    8
#2015-01-01 15:00:00    9
#Freq: 100T, dtype: int64
series_rs = series.resample('60T', how='mean')
print series_rs
#2015-01-01 00:00:00     0
#2015-01-01 01:00:00     1
#2015-01-01 02:00:00   NaN
#2015-01-01 03:00:00     2
#2015-01-01 04:00:00   NaN
#2015-01-01 05:00:00     3
#2015-01-01 06:00:00     4
#2015-01-01 07:00:00   NaN
#2015-01-01 08:00:00     5
#2015-01-01 09:00:00   NaN
#2015-01-01 10:00:00     6
#2015-01-01 11:00:00     7
#2015-01-01 12:00:00   NaN
#2015-01-01 13:00:00     8
#2015-01-01 14:00:00   NaN
#2015-01-01 15:00:00     9
#Freq: 60T, dtype: float64
series_rs = series.resample('60T', how='mean', fill_method='bfill')
print series_rs
#2015-01-01 00:00:00    0
#2015-01-01 01:00:00    1
#2015-01-01 02:00:00    2
#2015-01-01 03:00:00    2
#2015-01-01 04:00:00    3
#2015-01-01 05:00:00    3
#2015-01-01 06:00:00    4
#2015-01-01 07:00:00    5
#2015-01-01 08:00:00    5
#2015-01-01 09:00:00    6
#2015-01-01 10:00:00    6
#2015-01-01 11:00:00    7
#2015-01-01 12:00:00    8
#2015-01-01 13:00:00    8
#2015-01-01 14:00:00    9
#2015-01-01 15:00:00    9
#Freq: 60T, dtype: float64

Answer 2

请注意，fill_method 现已被弃用。resample()现在返回一个重采样对象，您可以像 groupby 对象一样对其执行操作。

常见的下采样操作：

.mean()
.sum()
.agg()
.apply()

上采样操作：

.ffill()
.bfill()

请参阅文档中的新消息 https://pandas.pydata.org/pandas-docs/stable/whatsnew.html#whatsnew-0180-writing-resample

所以这个例子会变成

series_rs = series.resample('60T').mean()