我有一个带有层次化索引(MultiIndex)的Pandas DataFrame。我通过对“ cousub”和“ year”进行分组来创建此DataFrame。
annualMed = df.groupby(["cousub", "year"])[["ratio", "sr_val_transfer"]].median().round(2)
print annualMed.head(8)
ratio sr_val_transfer
cousub year
Allen Park city 2013 0.51 75000.0
2014 0.47 85950.0
2015 0.47 95030.0
2016 0.45 102500.0
Belleville city 2013 0.49 113900.0
2014 0.55 114750.0
2015 0.53 149000.0
2016 0.48 121500.0
我希望在"年"级别中添加一个"总体"值,然后再根据"cousub"分组填充值,即排除"年"。我希望结果看起来像下面这样
ratio sr_val_transfer
cousub year
Allen Park city 2013 0.51 75000.0
2014 0.47 85950.0
2015 0.47 95030.0
2016 0.45 102500.0
Overall 0.50 90000.0
Belleville city 2013 0.49 113900.0
2014 0.55 114750.0
2015 0.53 149000.0
2016 0.48 121500.0
Overall 0.50 135000.0
我该如何将此新项添加到MultiIndex的“年份”级别中呢?