在python中旋转列表的有效方法 [英] Efficient way to rotate a list in python

问题描述

在python中旋转列表的最有效方法是什么? 现在我有这样的东西:

What is the most efficient way to rotate a list in python? Right now I have something like this:

>>> def rotate(l, n):
...     return l[n:] + l[:n]
... 
>>> l = [1,2,3,4]
>>> rotate(l,1)
[2, 3, 4, 1]
>>> rotate(l,2)
[3, 4, 1, 2]
>>> rotate(l,0)
[1, 2, 3, 4]
>>> rotate(l,-1)
[4, 1, 2, 3]

有更好的方法吗?

推荐答案

A c0> 已针对两端的推拉进行了优化.它们甚至具有专用的rotate()方法.

A collections.deque is optimized for pulling and pushing on both ends. They even have a dedicated rotate() method.

from collections import deque
items = deque([1, 2])
items.append(3)        # deque == [1, 2, 3]
items.rotate(1)        # The deque is now: [3, 1, 2]
items.rotate(-1)       # Returns deque to original state: [1, 2, 3]
item = items.popleft() # deque == [2, 3]

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