具有共享元素的python查找集

Question

例如，我的数据是一组冻结集

data = set([frozenset([1,2,3,4]), frozenset([3,4,5,6,7,8]), frozenset([100,200]), frozenset([1,1000, 2000])])

预期结果是具有重复元素的frozenset集，即

result = set([frozenset([1,2,3,4]), frozenset([3,4,5,6,7,8]),  frozenset([1,1000, 2000])])

这里frozenset([100,200])被删除，因为它不与其他冻结集共享任何元素。什么是实现这一目标的有效方法？你知道吗

Answer 1

您可以构建一个dict集合元素来计算它们被找到的次数，然后删除所有元素的计数为1的任何frozenset。collections.Counter会很方便。你知道吗

它的优点是O(n)，其中n是所有集合中元素的总数。你知道吗

from collections import Counter

data = set([frozenset([1,2,3,4]), frozenset([3,4,5,6,7,8]), frozenset([100,200]), frozenset([1,1000, 2000])])
counts = Counter(elt for fs in data for elt in fs)
result = {fs for fs in data if any(counts[elt] > 1 for elt in fs)}

# {frozenset({1, 2, 3, 4}), frozenset({1000, 1, 2000}), frozenset({3, 4, 5, 6, 7, 8})}