我有这个数据框:
ID date X1 X2 Y
A 16-07-19 58 50 0
A 21-07-19 28 74 0
B 25-07-19 54 65 1
B 27-07-19 50 30 0
B 29-07-19 81 61 0
C 30-07-19 55 29 0
C 31-07-19 97 69 1
C 03-08-19 13 48 1
D 19-07-18 77 27 1
D 20-07-18 68 50 1
D 22-07-18 89 57 1
D 23-07-18 46 70 0
D 26-07-18 56 13 0
E 06-08-19 47 35 1
我想按日期“拉伸(stretch)”数据，从第一行到每个 ID 的最后一行 (分组依据),
并用 NaN 填充缺失值。
例如:ID A 在 16-07-19 和 21-07-19 上有两行。
实现后，他(她)在2019年7月16-21日应该有6行。
预期结果:
ID date X1 X2 Y
A 16-07-19 58.0 50.0 0.0
A 17-07-19 NaN NaN NaN
A 18-07-19 NaN NaN NaN
A 19-07-19 NaN NaN NaN
A 20-07-19 NaN NaN NaN
A 21-07-19 28.0 74.0 0.0
B 25-07-19 54.0 65.0 1.0
B 26-07-19 NaN NaN NaN
B 27-07-19 50.0 30.0 0.0
B 28-07-19 NaN NaN NaN
B 29-07-19 81.0 61.0 0.0
C 30-07-19 55.0 29.0 0.0
C 31-07-19 97.0 69.0 1.0
C 01-08-19 NaN NaN NaN
C 02-08-19 NaN NaN NaN
C 03-08-19 13.0 48.0 1.0
D 19-07-18 77.0 27.0 1.0
D 20-07-18 68.0 50.0 1.0
D 21-07-18 NaN NaN NaN
D 22-07-18 89.0 57.0 1.0
D 23-07-18 46.0 70.0 0.0
D 24-07-18 NaN NaN NaN
D 25-07-18 NaN NaN NaN
D 26-07-18 56.0 13.0 0.0
E 06-08-19 47.0 35.0 1.0
最佳答案
使用DataFrame.asfreq每个使用 DatetimeIndex 的组:
df['date'] = pd.to_datetime(df['date'], dayfirst=True)
cols = df.columns.difference(['date','ID'], sort=False)
df = df.set_index('date').groupby('ID')[cols].apply(lambda x: x.asfreq('d')).reset_index()
print (df)
ID date X1 X2 Y
0 A 2019-07-16 58.0 50.0 0.0
1 A 2019-07-17 NaN NaN NaN
2 A 2019-07-18 NaN NaN NaN
3 A 2019-07-19 NaN NaN NaN
4 A 2019-07-20 NaN NaN NaN
5 A 2019-07-21 28.0 74.0 0.0
6 B 2019-07-25 54.0 65.0 1.0
7 B 2019-07-26 NaN NaN NaN
8 B 2019-07-27 50.0 30.0 0.0
9 B 2019-07-28 NaN NaN NaN
10 B 2019-07-29 81.0 61.0 0.0
11 C 2019-07-30 55.0 29.0 0.0
12 C 2019-07-31 97.0 69.0 1.0
13 C 2019-08-01 NaN NaN NaN
14 C 2019-08-02 NaN NaN NaN
15 C 2019-08-03 13.0 48.0 1.0
16 D 2018-07-19 77.0 27.0 1.0
17 D 2018-07-20 68.0 50.0 1.0
18 D 2018-07-21 NaN NaN NaN
19 D 2018-07-22 89.0 57.0 1.0
20 D 2018-07-23 46.0 70.0 0.0
21 D 2018-07-24 NaN NaN NaN
22 D 2018-07-25 NaN NaN NaN
23 D 2018-07-26 56.0 13.0 0.0
24 E 2019-08-06 47.0 35.0 1.0
另一个想法 DataFrame.reindex每组:
df['date'] = pd.to_datetime(df['date'], dayfirst=True)
cols = df.columns.difference(['date','ID'], sort=False)
f = lambda x: x.reindex(pd.date_range(x.index.min(), x.index.max()))
df = df.set_index('date').groupby('ID')[cols].apply(f).reset_index()
关于python - 按日期拉伸(stretch)数据框，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60146048/