在Pandas中给多层索引降级的方法

import pandas as pdimport numpy as npdf = pd.DataFrame(np.arange(0, 14).reshape(7,2),columns =['a','b'] )df.a = df.a %3df['who'] = 'Bob'df.loc[df.a%4==0,'who'] = 'Alice'

gp1 = df.groupby('who').agg({'b':[sum,np.max, np.min], 'a':sum})gp1

#有层次的索引访问方法gp1.loc['Bob', ('b', 'sum')]

28.0

gp2 = gp1.copy(deep=True)gp2.columns = gp1.columns.droplevel(0)gp2

gp3 = gp1.copy(deep=True)gp3.columns = ["_".join(x) for x in gp3.columns.ravel()]gp3