import pandas as pd
import numpy as np
# 创建dataframe
d = {
'Name':['Alisa','Bobby','Cathrine','Alisa','Bobby','Cathrine',
'Alisa','Bobby','Cathrine','Alisa','Bobby','Cathrine'],
'Semester':['Semester 1','Semester 1','Semester 1','Semester 1','Semester 1','Semester 1',
'Semester 2','Semester 2','Semester 2','Semester 2','Semester 2','Semester 2'],
'Subject':['Mathematics','Mathematics','Mathematics','Science','Science','Science',
'Mathematics','Mathematics','Mathematics','Science','Science','Science'],
'Score':[62,47,55,74,31,77,85,63,42,67,89,81]}
df = pd.DataFrame(d)
df
层级分组
df.groupby(by=['Semester', 'Subject'])['Score'].mean().to_frame()