有了以下DataFrame,我如何根据索引将“beyer”列进行移位,而不让Pandas将移位后的值分配给不同的索引值?
line_date line_race beyer
horse
Last Gunfighter 2013-09-28 10 99
Last Gunfighter 2013-08-18 10 102
Last Gunfighter 2013-07-06 8 103
.....
Paynter 2013-09-28 10 103
Paynter 2013-08-31 10 88
Paynter 2013-07-27 8 100
df['beyer'].shift(1)
产生...
line_date line_race beyer beyer_shifted
horse
Last Gunfighter 2013-09-28 10 99 NaN
Last Gunfighter 2013-08-18 10 102 99
Last Gunfighter 2013-07-06 8 103 102
.....
Paynter 2013-09-28 10 103 71
Paynter 2013-08-31 10 88 103
Paynter 2013-07-27 8 100 88
问题在于Paynter被赋予了一个与Last Gunfighter(他的第一次记录)相同的贝耶尔值。 相反,我希望它是这样的... line_date line_race beyer beyer_shifted
horse
Last Gunfighter 2013-09-28 10 99 NaN
Last Gunfighter 2013-08-18 10 102 99
Last Gunfighter 2013-07-06 8 103 102
.....
Paynter 2013-09-28 10 103 NaN
Paynter 2013-08-31 10 88 103
Paynter 2013-07-27 8 100 88