Python df在同一个单元格中保存多个值

Question

我有一个数据框，其中列是学生的姓名，行是成绩（每一行是不同的测试）。通过以下代码，我找到了每个测试的最高分

df.max(axis=1)

但是，现在我想知道哪个学生获得了最高分。因此，我想得到以下最后一列：

   Student 1 |  Student 2  |  Student 3  | Max_grade | Which_student
0      3.76  |     3.69    |  2.48       | 3.79      | Student 1
1      1.65  |     4.40    |  6.66       | 6.66      | Student 2
2      3.76  |     3.69    |  2.48       | 3.76      | Student 1
3      5.50  |     5.50    |  1.79       | 5.50      | Student 1, Student 2
4      5.50  |     4.50    |  1.79       | 5.50      | Student 1

如何获得每行的最高值？如果 2 名学生获得相同的分数，我想将两个名字都附加到最后一列。

我现在所做的是遍历所有值，例如：

for i in range(len(df)):
       for j in range(len(df.columns)-1):
                    if df.iloc[i,j] == df['Max_grade'].iloc[i]:
                         print(i,total_bets.columns[j])

这将返回以下内容：

0 Student 1
1 Student 2
2 Student 1
3 Student 1
3 Student 2
4 Student 1

但是，如何将第三行的两个学生组合在一起，以及如何将值保存在 df 中？

Answer 1

我用下面的代码解决了：

for i in range(len(df)):
    a = []
    for j in range(len(df.columns)-1):
        if df.iloc[i,j] == df['Max_grade'].iloc[i]:
            # df['which_student'].iloc[i].append(df.columns[j], axis=1)
            a.append(df.columns[j])
    df['which_student'].iloc[i] = a

Answer 2

student1 = [3.76, 1.65, 3.76, 5.50, 5.50]
student2 = [3.69, 4.40, 3.69, 5.50, 4.50]
student3 = [2.48, 6.66, 2.48, 1.79, 1.79]
df = pd.DataFrame({'Student 1': student1, 'Student 2': student2, 'Student 3': student3})
df['Max_grade'] = df.max(axis=1)
print(df)
whichstudent = []
for i in range(len(df)):
    maxstudent = []
    for j in range(len(df.columns)-1):
        if df.iloc[i,j] == df['Max_grade'].iloc[i]:
            student = df.columns[j]
            maxstudent.append(student)
    whichstudent.append(maxstudent)

whichstudents = []
for i in range(len(df)):
    allstudent = ''
    for j in range(len(whichstudent[i])):
        if len(whichstudent[i]) != 1:
            allstudent = allstudent + ', ' + whichstudent[i][j]
            allstudent = allstudent[1:len(allstudent)]
        else:
            allstudent = whichstudent[i][j]
    whichstudents.append(allstudent)


df['Which_student'] = whichstudents
print(df)

输出：

   Student 1  Student 2  Student 3  Max_grade
0       3.76       3.69       2.48       3.76
1       1.65       4.40       6.66       6.66
2       3.76       3.69       2.48       3.76
3       5.50       5.50       1.79       5.50
4       5.50       4.50       1.79       5.50
   Student 1  Student 2  Student 3  Max_grade         Which_student
0       3.76       3.69       2.48       3.76             Student 1
1       1.65       4.40       6.66       6.66             Student 3
2       3.76       3.69       2.48       3.76             Student 1
3       5.50       5.50       1.79       5.50  Student 1, Student 2
4       5.50       4.50       1.79       5.50             Student 1