在pandas中按行分组？

Question

当我的源数据还没有很好地分组时，我想要一种方法来执行分组和聚合函数。例如，给定以下数据帧：

#Create a DataFrame
d = {
    'Name':['Alisa','Bobby','Cathrine','Alisa','Bobby','Cathrine',
            'Alisa','Bobby','Cathrine','Alisa','Bobby','Cathrine'],
'Exam':['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]}

我希望能够打印一个按分数范围汇总结果的表，例如：

Score        Subject        Qty
60-70        Mathematics    2
             Science        1
70-80        Mathematics    1
             Science        2

到目前为止我还没能弄清楚这件事。有什么好主意吗？

Answer 1

尝试：

(df.groupby([pd.cut(df['Score'],bins=[60,70,80]),
             'Subject'])
   .size()
   .to_frame('Qty')
)

输出：

                      Qty
Score    Subject         
(60, 70] Mathematics    2
         Science        1
(70, 80] Mathematics    0
         Science        2