python - `Itertools.cycle` : most pythonic way to take multiple steps?

Question

我有一些列表，我想循环浏览它。问题是我对一次循环一个元素不感兴趣，但我想一次循环 n 个元素。

例如，如果我的列表是 l = ["a", "b", "c", "d"]，那么我需要以下输出:

>>> from itertools import cycle
>>> gen = cycle(l)
>>> next(gen, 4) # I know this doesn't work -- take as pseudocode
d
>>> next(gen, 3)
c

我知道我可以通过以下方式完成此任务:

def generator_step(g, n):
    for item in range(n):
        next(g)
     return item

Answer 1

您可以在调用 next 之前使用 itertools.islice 来推进循环对象:

from itertools import cycle, islice

c = cycle(l)
n = 4
print(next(islice(c, n-1, n)))
# d