要推断,您必须使用bfill()
and ffill()
。缺失值将由后向(或前向)值分配。
要进行线性插值,您必须使用函数interpolate
,但日期需要转换为数字:
import numpy as np
import pandas as pd
from datetime import datetime
bb = pd.DataFrame(data = {'date' :['','','','2015-09-02', '2015-09-02', '2015-09-03','','2015-09-08', '', '2015-09-11','2015-09-14','','' ]})
bb['date'] = pd.to_datetime(bb['date'], format="%Y-%m-%d")
# convert to seconds
tmp = bb['date'].apply(lambda t: (t-datetime(1970,1,1)).total_seconds())
# linear interpolation
tmp.interpolate(inplace=True)
# back convert to dates
bb['date'] = pd.to_datetime(tmp, unit='s')
bb['date'] = bb['date'].apply(lambda t: t.date())
# extrapolation for the first missing values
bb.bfill(inplace='True')
print bb
结果:
date
0 2015-09-02
1 2015-09-02
2 2015-09-02
3 2015-09-02
4 2015-09-02
5 2015-09-03
6 2015-09-05
7 2015-09-08
8 2015-09-09
9 2015-09-11
10 2015-09-14
11 2015-09-14
12 2015-09-14