使用itertools的Python中的Powerset

问题描述

我正在尝试在Python 3中创建电源集.我找到了对itertools的引用 模块，并且我使用了该页面上提供的powerset代码.问题:代码返回对itertools.chain对象的引用，而我想访问Powerset中的元素.我的问题:如何实现?

I'm trying to create a powerset in Python 3. I found a reference to the itertools module, and I've used the powerset code provided on that page. The problem: the code returns a reference to an itertools.chain object, whereas I want access to the elements in the powerset. My question: how to accomplish this?

在此先感谢您的见解.

推荐答案

itertools函数返回 迭代器 ，即按需延迟生成结果的对象.

itertools functions return iterators, objects that produce results lazily, on demand.

您可以使用for循环遍历对象，也可以通过在其上调用list()将结果转换为列表:

You could either loop over the object with a for loop, or turn the result into a list by calling list() on it:

from itertools import chain, combinations

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

for result in powerset([1, 2, 3]):
    print(result)

results = list(powerset([1, 2, 3]))
print(results)

您还可以将对象存储在变量中，并使用 next()函数逐一从迭代器获取结果.

You can also store the object in a variable and use the next() function to get results from the iterator one by one.

这篇关于使用itertools的Python中的Powerset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！