Python 如何将嵌套列表映射到可迭代字典

Question

我有一个 classes 的列表及其存储在配对列表中的先决条件：

classes = [
    ['Calculus', 'Geometry'],
    ['Trigonometry', 'Algebra'],
    ['Geometry', 'Trigonometry']
]

我想将这些 class 映射到特定索引，以使用类似以下内容为课程构建图表：

course_index = {
    0: 'Calculus'
    1: 'Geometry' 
    2: 'Trigonometry'
    3: 'Algebra'
}

获取新的整数映射mapped_classes = [[0,1],[2,3],[1,2]]

为了创建 course_index，我创建了一个空的索引 dict 并添加了 classes 中 course_index[=23= 中不存在的项目]

course_index = {key: "" for key in range(4)}

index = 0
for x, y in classes:
    if x not in course_index.values(): 
        course_index[index] = x
        index += 1
    if y not in course_index.values(): 
        course_index[index] = y
        index += 1

我想不通的是如何将 classes 映射到它们对应的 course_index 以创建 mapped_classes.

有没有什么映射函数可以简化这个过程？我尝试解决这个问题如下，我无法改变当前 class 列表中的值。嵌套循环的效率也很低。

for key, val in course_index: 
    for x, y in classes:
        if x = val: 
            x = key
        if y = val: 
            y = key

Answer 1

尝试使用这样的东西：

mapped_classes = classes.copy()
for key, val in course_index.items():
    for e, f in enumerate(classes):
        for x in f:
            if x == val:
                mapped_classes[e][mapped_classes[e].index(x)] = key
print(mapped_classes)

Answer 2

反转 course_index 词典。枚举类.

invert = {v: k for k, v in course_index.items()}
for i, row in enumerate(classes):
    classes[i][0] = invert[classes[i][0]]
    classes[i][1] = invert[classes[i][1]]
print(classes)

Python 如何将嵌套列表映射到可迭代字典

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