python - 测试集合是否为子集，考虑集合中每个元素的数量(多重性)

Question

我知道我可以测试 set1 是否是 set2 的子集:

{'a','b','c'} <= {'a','b','c','d','e'} # True

但以下也是正确的:

{'a','a','b','c'} <= {'a','b','c','d','e'} # True

我如何让它考虑集合中元素出现的次数，以便:

{'a','b','c'}     <= {'a','b','c','d','e'}      # True
{'a','a','b','c'} <= {'a','b','c','d','e'}      # False since 'a' is in set1 twice but set2 only once
{'a','a','b','c'} <= {'a','a','b','c','d','e'}  # True because both sets have two 'a' elements

我知道我可以这样做:

A, B, C = ['a','a','b','c'], ['a','b','c','d','e'], ['a','a','b','c','d','e']
all([A.count(i) == B.count(i) for i in A]) # False
all([A.count(i) == C.count(i) for i in A]) # True

但我想知道是否有更简洁的东西，比如 set(A).issubset(B,count=True) 或者避免列表理解的方法。谢谢!

Answer 1

如评论中所述，使用 Counter 的可能解决方案:

from collections import Counter

def issubset(X, Y):
    return len(Counter(X)-Counter(Y)) == 0