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python - 如何按字典中列表的值排序

问题描述

按值排序字典列表我一直在尝试使用 lambda，但我无法弄清楚。

scale = {'A+': 4.3, 'A': 4.0, 'A-': 3.7,
   'B+': 3.3, 'B': 3.0, 'B-': 2.7,
   'C+': 2.3, 'C': 2.0, 'C-': 1.7,
   'D+': 1.3, 'D': 1.0, 'D-': 0.7,
   'F' : 0.0}

subject = {'math':  {('Tom', 'B'), ('Kevin','D')},
   'History':  {('Kate', 'A+'),('Eric','C'),('Hannah','F')}, 
   'English':  {('Eli', 'B-')}}`
from collections import defaultdict
mingrade = 1.7
def pass(subject, mingrade):
    output = defaultdict(list)
    for subject_name,subject_grade in subject.items():
        for student,grade in subject_grade:
        if scale[grade]>=mingrade:
            output[subject_name]+=[student]
return output

我得到像 {'math': ['Tom'], 'History': {('Kate'),('Eric')},'English': {('Eli')} 这样的输出，但我想按姓名和成绩，例如 'History': {('Kate'),('Eric') 将变为 'History': {('Eric'),('Kate')} 按字母顺序排列。另一个我想按年级得到它。成绩高的学生排在第一位。

标签： pythonsortingdictionary

解决方案

好的，所以为了获得具有两种不同类型的两个不同输出，我获取了您的代码，然后为您的函数创建了两个输出，其中一个按字母顺序排序，一个按等级排序。

scale = {'A+': 4.3, 'A': 4.0, 'A-': 3.7,
   'B+': 3.3, 'B': 3.0, 'B-': 2.7,
   'C+': 2.3, 'C': 2.0, 'C-': 1.7,
   'D+': 1.3, 'D': 1.0, 'D-': 0.7,
   'F' : 0.0}

subject = {'math':  {('Tom', 'B'), ('Kevin','D')},
   'History':  {('Kate', 'A+'),('Eric','C'),('Hannah','F')}, 
   'English':  {('Eli', 'B-')}}
from collections import defaultdict
mingrade = 1.7
def test(subject, mingrade):
    alpha_sort = defaultdict(list)
    grade_sort = defaultdict(list)
    for subject_name,subject_grade in subject.items():
        #here i sort the sets first alphabetically and then by grade
        #the sorted function allows me to pass a function on which i want
        #to sort them as with the key keyword
        sort_alpha = sorted(subject_grade, key=lambda x: x[0].lower())
        sort_grade = sorted(subject_grade, key=lambda x: scale[x[1]], reverse=True)
        #now I loop over each sorted list as you did and store them in a 
        #seperate default dicts
        for student,grade in sort_grade:
            if scale[grade]>=mingrade:
                grade_sort[subject_name]+=[student]
        for student,grade in sort_alpha:
            if scale[grade]>=mingrade:
                alpha_sort[subject_name]+=[student]

    return alpha_sort, grade_sort
alpha, grade = test(subject, mingrade)
print(alpha, grade)

这给出了这个输出

defaultdict(<class 'list'>, {'math': ['Tom'], 'History': ['Eric', 'Kate'], 
'English': ['Eli']}) 
defaultdict(<class 'list'>, {'math': ['Tom'], 'History': ['Kate', 'Eric'], 
'English': ['Eli']})

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