Python - 使用“set”查找列表中的不同项目
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Python - Use 'set' to find the different items in list
提问by RPiAwesomeness
I need to compare two lists in Python, and I know about using the setcommand to find similar items, but is there a another command I could use that would automatically compare them, instead of having to code for it?
我需要在 Python 中比较两个列表，并且我知道如何使用该set命令来查找相似的项目，但是是否可以使用另一个命令来自动比较它们，而不必为其编写代码？
I would like to find the items that aren't in each one. Say list one is as follows:
我想找到每个项目中没有的项目。说清单一如下：
[1, 2, 3, 4, 5, 6]
and list two is:
清单二是：
[1, 2, 3, 4, 6]
I want to find that 5is missing from the list, hopefully by a command, but I do know how to loop through comparing.
我想5从列表中找到它，希望通过命令，但我知道如何循环比较。
采纳答案by tifon
Looks like you need symmetric difference:
看起来你需要对称差异：
a = [1,2,3]
b = [3,4,5]
print(set(a)^set(b))
>>> [1,2,4,5]
回答by Seth
The docsare a good place to start. Here are a couple examples that might help you determine how you want to compare your sets.
该文档是一个良好的开端。以下是一些示例，可以帮助您确定要如何比较您的集合。
To find the intersection (items that are in both sets):
要找到交集（两个集合中的项目）：
>>> a = set([1, 2, 3, 4, 5, 6])
>>> b = set([4, 5, 6, 7, 8, 9])
>>> a & b
set([4, 5, 6])
To find the difference (items that only in one set):
找出差异（仅在一组中的项目）：
>>> a = set([1, 2, 3, 4, 5, 6])
>>> b = set([4, 5, 6, 7, 8, 9])
>>> a - b
set([1, 2, 3])
>>> b - a
set([7, 8, 9])
To find the symmetric difference (items that are in one or the other, but not both):
要找到对称差异（在一个或另一个中的项目，但不是两个）：
>>> a = set([1, 2, 3, 4, 5, 6])
>>> b = set([4, 5, 6, 7, 8, 9])
>>> a ^ b
set([1, 2, 3, 7, 8, 9])
Hope that helps.
希望有帮助。
回答by Fredrik Pihl
A simple list comprehension
一个简单的列表理解
In [1]: a=[1, 2, 3, 4, 5, 6]
In [2]: b=[1, 2, 3, 4, 6]
In [3]: [i for i in a if i not in b]
Out[3]: [5]
