如何在 Python 中反转元组?

问题描述

可能重复:
在Python中逆序遍历列表

这可能吗?不必就位，只需寻找一种反转元组的方法，以便我可以反向迭代它.

Is this possible? Doesn't have to be in place, just looking for a way to reverse a tuple so I can iterate on it backwards.

推荐答案

有两种惯用的方法:

reversed(x)  # returns an iterator

或

x[::-1]  # returns a new tuple

由于元组是不可变的，因此无法就地反转元组.

Since tuples are immutable, there is no way to reverse a tuple in-place.

基于@lvc 的注释，由 reversed 返回的迭代器将等效于

Building on @lvc's comment, the iterator returned by reversed would be equivalent to

def myreversed(seq):
    for i in range(len(x) - 1, -1, -1):
        yield seq[i]

即它依赖于具有已知长度的序列来避免必须实际反转元组.

i.e. it relies on the sequence having a known length to avoid having to actually reverse the tuple.

至于哪个更有效，我怀疑它会是 seq[::-1] 如果你正在使用它并且元组很小，并且 当元组很大时反转，但是python中的性能常常令人惊讶，所以测量一下！

As to which is more efficient, i'd suspect it'd be the seq[::-1] if you are using all of it and the tuple is small, and reversed when the tuple is large, but performance in python is often surprising so measure it!

这篇关于如何在 Python 中反转元组?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！