从迭代器中删除N个值的Pythonic解决方案 [英] Pythonic solution to drop N values from an iterator

问题描述

是否存在从迭代器中删除n值的pythonic解决方案?您可以通过如下方式丢弃n值来做到这一点:

Is there a pythonic solution to drop n values from an iterator? You can do this by just discarding n values as follows:

def _drop(it, n):
    for _ in xrange(n):
        it.next()

但这是IMO，不如Python代码那么优雅.我在这里缺少更好的方法吗?

But this is IMO not as elegant as Python code should be. Is there a better approach I am missing here?

推荐答案

我相信您正在寻找食用"食谱

I believe you are looking for the "consume" recipe

http://docs.python.org/library/itertools.html#recipes

def consume(iterator, n):
    "Advance the iterator n-steps ahead. If n is none, consume entirely."
    # Use functions that consume iterators at C speed.
    if n is None:
        # feed the entire iterator into a zero-length deque
        collections.deque(iterator, maxlen=0)
    else:
        # advance to the empty slice starting at position n
        next(islice(iterator, n, n), None)

如果n为None时不需要特殊行为， 您可以使用

If you don't need the special behaviour when n is None, you can just use

next(islice(iterator, n, n), None)

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