Question

我需要在两个对应ID之间的熊猫数据框中填充缺失值。考虑以下示例：

import pandas as pd
import numpy as np
df = pd.DataFrame({'Date' : pd.date_range('20130101',periods=12),
                   'ID' :[np.NaN,1,np.NaN,np.NaN,1,np.NaN,2,np.NaN,np.NaN,np.NaN,2,np.NaN]})

所需的输出：

        Date    ID
0   2013-01-01  NaN
1   2013-01-02  1.0
2   2013-01-03  1.0
3   2013-01-04  1.0
4   2013-01-05  1.0
5   2013-01-06  NaN
6   2013-01-07  2.0
7   2013-01-08  2.0
8   2013-01-09  2.0
9   2013-01-10  2.0
10  2013-01-11  2.0
11  2013-01-12  NaN

我该怎么做？

Answer 1

比较正向和反向填充值并仅在相同的情况下设置值：

s = df['ID'].ffill()
m = s == df['ID'].bfill()
df.loc[m, 'ID'] = s
#alternative
#df['ID'] = df['ID'].mask(m, s)
print (df)
         Date   ID
0  2013-01-01  NaN
1  2013-01-02  1.0
2  2013-01-03  1.0
3  2013-01-04  1.0
4  2013-01-05  1.0
5  2013-01-06  NaN
6  2013-01-07  2.0
7  2013-01-08  2.0
8  2013-01-09  2.0
9  2013-01-10  2.0
10 2013-01-11  2.0
11 2013-01-12  NaN

熊猫-如何在对应的ID之间填充缺失值？

1 个答案: