Python 查找嵌套列表程序的第二大编号

在一个由N名学生组成的物理课堂上，为每个学生提供姓名和成绩，将其存储在嵌套列表中，并打印所有成绩第二低的学生的姓名

注意：如果有多个学生成绩相同，请按字母顺序排列他们的名字，并在新行上打印每个名字

输入

以下是我回答上述问题的代码：-

marks = sorted([student[i][1] for i in range(len(student))], reverse = True)

for num in range(1,len(marks)):
    if marks[num] < marks[0]:
        if marks[num+1] < marks[num]:
            temp = marks[num+1]
            break
    else:
        continue
second_top = [student[i] for i in range(len(student)) if student[i][1] == temp]

topper = sorted([k for k,l in second_top])

for i in range(len(topper)):
    print(topper[i])

---

是否有办法改进此代码。我是Python新手，开始在黑客级别上练习

students = [['Harry', 37.21], ['Berry', 37.21], ['Tina', 37.2], ['Akriti', 41], ['Harsh', 39]]

ranked = sorted(students, key=lambda a: (a[1], a[0]))

second_best = ranked[1][1]  # or whichever rank you want

print(ranked)

ex_aequos = [s for s in ranked if s[1] == second_best]

print(ex_aequos)  

结果:

[['Akriti', 41], ['Harsh', 39], ['Berry', 37.21], ['Harry',
 37.21], ['Tina', 37.2]]
[['Berry', 37.21], ['Harry', 37.21]]

---

试试这个，这也解释了ex aequos的原因：

students = [['Harry', 37.21], ['Berry', 37.21], ['Tina', 37.2], ['Akriti', 41], ['Harsh', 39]]

ranked = sorted(students, key=lambda a: (a[1], a[0]))

second_best = ranked[1][1]  # or whichever rank you want

print(ranked)

ex_aequos = [s for s in ranked if s[1] == second_best]

print(ex_aequos)  

结果:

[['Akriti', 41], ['Harsh', 39], ['Berry', 37.21], ['Harry',
 37.21], ['Tina', 37.2]]
[['Berry', 37.21], ['Harry', 37.21]]

---

您可以使用列表理解和：

输出：

Berry
Harry

Berry
Harry

另一种方法是将您的数据存储在一个表中，其中键是分数，值是一个列表，其中包含所有具有键指定的分数的学生：

from collections import defaultdict

grade_student = defaultdict(list)
for student, grade in students:
    grade_student[grade].append(student)

# second lowest grade   
second_grade = sorted(grade_student.keys())[1]

# order the names alphabetically and print each name on a new line
print(*sorted(grade_student[second_grade]), sep='\n')

输出：

Berry
Harry

Berry
Harry

---

您可以使用列表理解和：

输出：

Berry
Harry

Berry
Harry

另一种方法是将您的数据存储在一个表中，其中键是分数，值是一个列表，其中包含所有具有键指定的分数的学生：

from collections import defaultdict

grade_student = defaultdict(list)
for student, grade in students:
    grade_student[grade].append(student)

# second lowest grade   
second_grade = sorted(grade_student.keys())[1]

# order the names alphabetically and print each name on a new line
print(*sorted(grade_student[second_grade]), sep='\n')

输出：

Berry
Harry

Berry
Harry

---

首先，我将按y升序对等级进行排序：

>>> students = [['Harry', 37.21], ['Berry', 37.21], ['Tina', 37.2], ['Akriti', 41], ['Harsh', 39]]
>>> grades = sorted(set(g for _, g in students))
>>> grades
[37.2, 37.21, 39, 41]

学生中g，g的行集合提取成绩并删除重复集合

然后选择列表中的第二个元素，即第二个最低等级：

>>> second_lowest_grade = grades[1]
>>> second_lowest_grade
37.21

>>> for name in sorted(n for n, g in students if g == second_lowest_grade):
...     print(name)
... 
Berry
Harry

然后为成绩第二低的学生循环排列好的名字：

>>> second_lowest_grade = grades[1]
>>> second_lowest_grade
37.21

>>> for name in sorted(n for n, g in students if g == second_lowest_grade):
...     print(name)
... 
Berry
Harry

---

首先，我将按y升序对等级进行排序：

>>> students = [['Harry', 37.21], ['Berry', 37.21], ['Tina', 37.2], ['Akriti', 41], ['Harsh', 39]]
>>> grades = sorted(set(g for _, g in students))
>>> grades
[37.2, 37.21, 39, 41]

学生中g，g的行集合提取成绩并删除重复集合

然后选择列表中的第二个元素，即第二个最低等级：

>>> second_lowest_grade = grades[1]
>>> second_lowest_grade
37.21

>>> for name in sorted(n for n, g in students if g == second_lowest_grade):
...     print(name)
... 
Berry
Harry

然后为成绩第二低的学生循环排列好的名字：

>>> second_lowest_grade = grades[1]
>>> second_lowest_grade
37.21

>>> for name in sorted(n for n, g in students if g == second_lowest_grade):
...     print(name)
... 
Berry
Harry