如何在列表列表中查找公共元素? [英] How to find common elements in list of lists?
问题描述
我想弄清楚如何比较 n 个列表以找到公共元素.例如:
I'm trying to figure out how to compare an n number of lists to find the common elements. For example:
p=[ [1,2,3],
[1,9,9],
..
..
[1,2,4]
>> print common(p)
>> [1]
现在,如果我知道元素的数量,我可以进行如下比较:
Now if I know the number of elements I can do comparions like:
for a in b:
for c in d:
for x in y:
...
但是如果我不知道 p 有多少个元素,那将不起作用.我看过这个比较两个列表的解决方案https://stackoverflow.com/a/1388864/1320800
but that wont work if I don't know how many elements p has. I've looked at this solution that compares two lists https://stackoverflow.com/a/1388864/1320800
但是在花了 4 个小时试图找出一种方法来实现递归之后,我仍然无法找到解决方案,因此非常感谢任何帮助!
but after spending 4 hrs trying to figure a way to make that recursive, a solution still eludes me so any help would be highly appreciated!
推荐答案
您正在寻找所有子列表的集合交集,您应该用于集合操作的数据类型是集合:
You are looking for the set intersection of all the sublists, and the data type you should use for set operations is a set:
result = set(p[0])
for s in p[1:]:
result.intersection_update(s)
print result
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