python - 将第二个副本中的值移动到第一个副本

Question

这篇文章是将最后一行的值分配给第一行:Move last value to first value .

我想将第二个副本中的值移动到第一个副本并将其他副本设置为 NaT。

ID  OutBedTime        DateOutBed1   16/05/2018 0:17   16/05/20181   16/05/2018 4:05   16/05/20181   16/05/2018 6:05   16/05/20181   17/05/2018 1:27   17/05/20181   17/05/2018 4:41   17/05/20181   17/05/2018 5:32   17/05/2018

预期输出

ID  OutBedTime        DateOutBed    TimeOutBedFinal1   16/05/2018 0:17   16/05/2018    16/05/2018 4:051   16/05/2018 4:05   16/05/2018    NaT1   16/05/2018 6:05   16/05/2018    NaT1   17/05/2018 1:27   17/05/2018    17/05/2018 4:411   17/05/2018 4:41   17/05/2018    NaT1   17/05/2018 5:32   17/05/2018    NaT

谢谢。

Answer 1

让我们用 apply 做 reindex 并选择 row 的第二个，然后像我们在上一个问题中做的一样

df['New']=df.groupby('DateOutBed')['OutBedTime'].apply(lambda x : x.iloc[[1]]).reset_index(level=1,drop=True).reindex(df.DateOutBed).values
df['New']=df.New.mask(df.DateOutBed.duplicated())
df
   ID      OutBedTime  DateOutBed             New
0   1  16/05/20180:17  16/05/2018  16/05/20184:05
1   1  16/05/20184:05  16/05/2018             NaN
2   1  16/05/20186:05  16/05/2018             NaN
3   1  17/05/20181:27  17/05/2018  17/05/20184:41
4   1  17/05/20184:41  17/05/2018             NaN
5   1  17/05/20185:32  17/05/2018             NaN

检查更新

df['New']=df.groupby('DateOutBed')['OutBedTime'].transform(lambda x : x.iloc[1] if len(x)>1 else x.iloc[0])
df['New']=df.New.mask(df.DateOutBed.duplicated())