为什么Python集不可哈希？ [英] Why aren't Python sets hashable?

问题描述

我偶然发现了一篇博文，详细介绍了如何在Python中实现powerset函数。所以我尝试着用我自己的方式去做，并发现Python显然不能有一组集合，因为集合不可散列。这很令人厌烦，因为powerset的定义是它是一组集合，我想用实际集合操作来实现它。

I stumbled across a blog post detailing how to implement a powerset function in Python. So I went about trying my own way of doing it, and discovered that Python apparently cannot have a set of sets, since set is not hashable. This is irksome, since the definition of a powerset is that it is a set of sets, and I wanted to implement it using actual set operations.

>>> set([ set() ])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'set'

Python是否有很好的理由可拆分的？

Is there a good reason Python sets are not hashable?

推荐答案

通常，Python中只有不可变对象是可散列的。 set（） - frozenset（）的不可变变体是可散列的。

Generally, only immutable objects are hashable in Python. The immutable variant of set() -- frozenset() -- is hashable.

这篇关于为什么Python集不可哈希？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！