Python:如何更改设置为索引的 pandas 中的日期

Question

我需要将最后日期设置为今天日期。示例:2016-05-18 至 2017-06-05。但是，当我执行 df.index[-1] = Today 时，它会返回此错误类型错误:索引不支持可变操作

>>> today
0   2017-06-05
Name: trading_day, dtype: datetime64[ns]


           Stock      Open      High       Low     Close Adj Close  Volume
Date                                                                      
2016-05-13   AAD  5.230000  5.260000  5.200000  5.260000  5.260000    5000
2016-05-16   AAD  5.220000  5.260000  5.220000  5.260000  5.260000    6000
2016-05-17   AAD  5.210000  5.260000  5.210000  5.260000  5.260000    2000
2016-05-18   AAD  5.200000  5.250000  5.200000  5.250000  5.250000    3000  

>>> df.index[-1] = today
TypeError: Index does not support mutable operations

我需要的是

           Stock      Open      High       Low     Close Adj Close  Volume
Date                                                                      
2016-05-13   AAD  5.230000  5.260000  5.200000  5.260000  5.260000    5000
2016-05-16   AAD  5.220000  5.260000  5.220000  5.260000  5.260000    6000
2016-05-17   AAD  5.210000  5.260000  5.210000  5.260000  5.260000    2000
2017-06-05   AAD  5.200000  5.250000  5.200000  5.250000  5.250000    3000

仅更改最后日期。

Answer 1

您可以使用重命名

df.rename({df.index[-1]: 'today'}, inplace = True)

你得到了

        Stock   Open    High    Low Close   Adj Close.1 Volume
Date                                
2016-05-13  AAD     5.23    5.26    5.20    5.26    5.26    5000
2016-05-16  AAD     5.22    5.26    5.22    5.26    5.26    6000
2016-05-17  AAD     5.21    5.26    5.21    5.26    5.26    2000
today       AAD     5.20    5.25    5.20    5.25    5.25    3000

将代码更改为

import datetime as dt    
df.rename({df.index[-1]: dt.date.today()}, inplace = True)

你会得到

    Stock   Open    High    Low Close   Adj Close.1 Volume
Date                                
2016-05-13  AAD     5.23    5.26    5.20    5.26    5.26    5000
2016-05-16  AAD     5.22    5.26    5.22    5.26    5.26    6000
2016-05-17  AAD     5.21    5.26    5.21    5.26    5.26    2000
2016-06-05  AAD     5.20    5.25    5.20    5.25    5.25    3000