从Python列表中获取n个项目组的惯用方法？ [英] idiomatic way to take groups of n items from a list in Python?

问题描述

给出一个清单

A = [1 2 3 4 5 6]

是否有任何惯用（Pythonic）方法迭代它，就好像它是

Is there any idiomatic (Pythonic) way to iterate over it as though it were

B = [(1, 2) (3, 4) (5, 6)]

除了索引之外？这感觉就像C的延续：

other than indexing? That feels like a holdover from C:

for a1,a2 in [ (A[i], A[i+1]) for i in range(0, len(A), 2) ]:

我不能帮助，但觉得应该有一些聪明的黑客使用itertools或切片等。

I can't help but feel there should be some clever hack using itertools or slicing or something.

（当然，一次两个只是一个例子;我想要一个解决方案适用于任何n。）

(Of course, two at a time is just an example; I'd like a solution that works for any n.)

编辑：相关在Python中一次迭代字符串2（或n）个字符但是即使是最干净的解决方案（使用zip接受）也没有在没有列表理解和* -notation的情况下很好地推广到更高的n。

related Iterate over a string 2 (or n) characters at a time in Python but even the cleanest solution (accepted, using zip) doesn't generalize well to higher n without a list comprehension and *-notation.

推荐答案

来自 http://docs.python.org/library/itertools.html ：

from itertools import izip_longest
def grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)

i = grouper(3,range(100))
i.next()
(0, 1, 2)

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