如何在Python中创建一组集?

问题:如何在Python中创建一组集?

我正在尝试在Python中设置一组。我不知道该怎么做。

从空集开始xx

xx = set([])
# Now we have some other set, for example
elements = set([2,3,4])
xx.add(elements)

但我明白了

TypeError: unhashable type: 'list'

要么

TypeError: unhashable type: 'set'

Python中可能有一组集合吗?

我正在处理大量集合,但我希望不必处理重复的集合(集合A1,集合A2,….的集合B,如果Ai = Aj,则“将取消”两个集合)

I’m trying to make a set of sets in Python. I can’t figure out how to do it.

Starting with the empty set xx:

xx = set([])
# Now we have some other set, for example
elements = set([2,3,4])
xx.add(elements)

but I get

TypeError: unhashable type: 'list'

or

TypeError: unhashable type: 'set'

Is it possible to have a set of sets in Python?

I am dealing with a large collection of sets and I want to be able to not have to deal duplicate sets (a set B of sets A1, A2, …., An would “cancel” two sets if Ai = Aj)


回答 0

Python的抱怨是因为内部set对象是可变的,因此不可散列。解决方案是frozenset用于内部集,以表明您无意修改它们。

Python’s complaining because the inner set objects are mutable and thus not hashable. The solution is to use frozenset for the inner sets, to indicate that you have no intention of modifying them.


回答 1

人们已经提到您可以使用Frozenset()做到这一点,所以我将添加一个代码来实现此目的:

例如,您要从以下列表列表中创建一组集合:

t = [[], [1, 2], [5], [1, 2, 5], [1, 2, 3, 4], [1, 2, 3, 6]]

您可以通过以下方式创建集合:

t1 = set(frozenset(i) for i in t)

People already mentioned that you can do this with a frozenset(), so I will just add a code how to achieve this:

For example you want to create a set of sets from the following list of lists:

t = [[], [1, 2], [5], [1, 2, 5], [1, 2, 3, 4], [1, 2, 3, 6]]

you can create your set in the following way:

t1 = set(frozenset(i) for i in t)

回答 2

frozenset在内部使用。


回答 3

所以我有完全相同的问题。我想制作一个可以作为一组集合使用的数据结构。问题在于集合必须包含不可变的对象。因此,您可以做的只是将其作为一组元组。对我来说很好!

A = set()
A.add( (2,3,4) )##adds the element
A.add( (2,3,4) )##does not add the same element
A.add( (2,3,5) )##adds the element, because it is different!

So I had the exact same problem. I wanted to make a data structure that works as a set of sets. The problem is that the sets must contain immutable objects. So, what you can do is simply make it as a set of tuples. That worked fine for me!

A = set()
A.add( (2,3,4) )##adds the element
A.add( (2,3,4) )##does not add the same element
A.add( (2,3,5) )##adds the element, because it is different!

回答 4

截至2020年,Python官方文档建议使用frozenset表示集合集。

As of 2020, the official Python documentation advise using frozenset to represent sets of sets.