如何检查列表中的所有元素是否符合条件？

我有一个列表，其中包含许多子列表，每个子列表包含 3 个元素，例如：

my_list = [["a", "b", 0], ["c", "d", 0], ["e", "f", 0], .....]

每个子列表的最后一个元素是一个排序标志，每个子列表的初始值为 0。随着我的算法的进展，我想检查该标志是否至少有一个元素为 0。目前我使用 while 循环，如下所示：

def check(list_):
    for item in list_:
        if item[2] == 0:
            return True
    return False

只要满足该条件，整个算法就会循环，并在每次迭代中设置一些标志：

while check(my_list):
    for item in my_list:
        if condition:
            item[2] = 1
        else:
            do_sth()

因为它引起问题 https://stackoverflow.com/questions/6260089/为了在迭代列表时从列表中删除元素，我使用这些标志来跟踪已处理的元素。

如何简化或加速代码？

_{See also Pythonic way of checking if a condition holds for any element of a list https://stackoverflow.com/questions/1342601/ for checking the condition for any element. Keep in mind that "any" and "all" checks are related through De Morgan's law https://stackoverflow.com/questions/2168603/, just as "or" and "and" are related.}

_{Existing answers here use the built-in function all to do the iteration. See How do Python's any and all functions work? https://stackoverflow.com/questions/19389490 for an explanation of all and its counterpart, any.}

_{If the condition you want to check is "is found in another container", see How to check if all of the following items are in a list? https://stackoverflow.com/questions/3931541/ and its counterpart, How to check if one of the following items is in a list? https://stackoverflow.com/questions/740287. Using any and all will work, but more efficient solutions are possible.}

这里最好的答案是使用all() http://docs.python.org/library/functions.html#all，这是这种情况的内置函数。我们将其与生成器表达式 https://www.youtube.com/watch?v=t85uBptTDYY干净高效地产生您想要的结果。例如：

>>> items = [[1, 2, 0], [1, 2, 0], [1, 2, 0]]
>>> all(flag == 0 for (_, _, flag) in items)
True
>>> items = [[1, 2, 0], [1, 2, 1], [1, 2, 0]]
>>> all(flag == 0 for (_, _, flag) in items)
False

注意all(flag == 0 for (_, _, flag) in items)直接等价于all(item[2] == 0 for item in items)，在这种情况下阅读起来会更好一点。

并且，对于过滤器示例，列表理解（当然，您可以在适当的情况下使用生成器表达式）：

>>> [x for x in items if x[2] == 0]
[[1, 2, 0], [1, 2, 0]]

如果你想检查至少一个元素是否为 0，更好的选择是使用any() http://docs.python.org/library/functions.html#any哪个更具可读性：

>>> any(flag == 0 for (_, _, flag) in items)
True