问题描述
我在互联网上找不到任何有效的例子,我可以看到它们之间的区别以及为什么选择其中一个。
I could not find any valid example on the internet where I can see the difference between them and why to choose one over the other.
推荐答案
第一个接受0个或多个参数,每个参数都是一个可迭代的,第二个参数接受一个参数,该参数可以产生迭代:
The first takes 0 or more arguments, each an iterable, the second one takes one argument which is expected to produce the iterables:
itertools.chain(list1, list2, list3)
iterables = [list1, list2, list3]
itertools.chain.from_iterable(iterables)
但是 iterables
可以是产生迭代的任何迭代器。
but iterables
can be any iterator that yields the iterables.
def generate_iterables():
for i in range(10):
yield range(i)
itertools.chain.from_iterable(generate_iterables())
通常使用第二种形式一个方便的例子,但因为它懒洋洋地循环输入迭代,它也是链接无限数量的有限迭代器的唯一方法:
Using the second form is usually a case of convenience, but because it loops over the input iterables lazily, it is also the only way you can chain a infinite number of finite iterators:
def generate_iterables():
while True:
for i in range(5, 10):
yield range(i)
itertools.chain.from_iterable(generate_iterables())
以上示例将给出你是一个迭代,它产生一个永远不会停止的循环数字模式,但永远不会消耗比单个 range()
调用所需的内存更多的内存。
The above example will give you a iterable that yields a cyclic pattern of numbers that will never stop, but will never consume more memory than what a single range()
call requires.
这篇关于在itertools中chain和chain.from_iterable有什么区别?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!