获取列表中只出现两次而不超过两次的元素的值

Question

我有一个元素列表，我想将这些元素存储在列表中，这些元素只出现两次，不超过两次或少于两次

list = [595, 595, 344, 344, 628, 628, 628, 353, 353, 353, 353, 353]

从列表中，我希望输出为result = [595,344]

下面的代码只返回一个元素

def has1dup(lst):
    setlst = list(set(lst)) # no duplicate elements
    for i in range(len(setlst)): # while the setlist's element count, 
        if lst.count(setlst[i]) > 1: # if the count of setlist[i] of lst is bigger than 1
            return setlst[i] # return it

Answer 1

您可以利用来自collections的Counter

例如

>>> from collections import Counter
>>> l = [595, 595, 344, 344, 628, 628, 628, 353, 353, 353, 353, 353]
>>> new_dict=Counter(l)
>>> new_dict
Counter({353: 5, 628: 3, 595: 2, 344: 2})
>>> [key for key, val in new_dict.items() if val == 2]
[595, 344]