Python: 从列表中删除项直到满足条件的惯用方法是什么？

Question

我刚写了一个小工具，但我感觉这种东西“应该早就有了”。它叫什么呢？

@listify
def drop_up_to_and_including(l, f):
    """Drops items from a list 'l' up until and including an element `e` is found for which `f(e) == True`

    Example::
    >>> drop_up_to_and_including(range(10), lambda x: x == 5)
    [6, 7, 8, 9]
    """
    found = False
    for e in l:
        if found:
            yield e

        if f(e):
            # note: after yield-statement; so we'll yield starting from the first item _after_ f(e) == True
            found = True

listify的功能就是你想的那样：https://github.com/shazow/unstdlib.py/blob/master/unstdlib/standard/list_.py#L149

相关文章：

• 暂无相关问题

Answer 1

根据评论的帮助：

>>> drop_up_to_and_including = lambda f, l: list(dropwhile(f, l))[1:]
>>> drop_up_to_and_including(lambda x: x != 5, range(10))
[6, 7, 8, 9]

调整参数的顺序，以便“更贴近常用的写法”，同时支持柯里化。

Answer 2

你可以使用 itertools.dropwhile 这个工具，但你需要先去掉第一个符合条件的元素，并且要反转一下逻辑：

drop_up_to_and_including = lambda l,f : list(itertools.dropwhile(lambda y: not(f(y)),l))[1:]