在Python中使用'in'测试一个子列表中的另一个子列表的一部分 [英] Using 'in' to test for part of one sublist in another in Python

问题描述

此处的新手尝试在另一个子列表中搜索一个子列表的一部分.

Newbie here trying to search for part of one sublist within another sublist.

list_1 = [[1, 2, 9], [4, 5, 8]]
list_2 = [[1, 2, 3], [4, 5, 6], [1, 2, 5]]

for item in list_1:
    for otherItem in list_2:
        item[0:2] in otherItem[0:2]

我希望这会回来

True
False
True
False
True
False

但是，每次迭代我都会得到错误的结果. 简而言之:

But instead I get false for every iteration. In a nutshell:

list_1[0][0:2] == list_2[0][0:2] #this returns true
list_1[0][0:2] in list_2[0][0:2] #this returns false

我想我不明白in的工作原理.有人可以在这里教我吗?

I guess I don't understand how in works. Can anyone school me here?

推荐答案

in查看一个子列表是否是另一列表的 (不是子列表):

in looks to see if one sublist is an element (not sublist) of another list:

[1,2] in [[1,2],[3,4]]

将是True.

[1,2] in [1,2,3]

将是False，

[1,2] in [1,2]

但是:

[1,2] == [1,2]

将是True.根据您实际尝试执行的操作，set对象可能会有用.

would be True. Depending on what you're actually trying to do, set objects might be useful.

a = [1,2]
b = [1,2,3]
c = [3,2,1]
d = [1,1,1]
e = set(a)
len(e.intersection(b)) == len(a)  #True
len(e.intersection(c)) == len(a)  #True -- Order of elements does not matter
len(e.intersection(d)) == len(a)  #False

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