python的sorted()函数是否保证稳定? [英] Is python's sorted() function guaranteed to be stable?

问题描述

文档不能保证这一点.还有其他记录在案的地方吗?

The documentation doesn't guarantee that. Is there any other place that it is documented?

我猜想它可能是稳定的，因为列表上的排序方法是保证是稳定的(注意第9点:从Python 2.3开始，保证sort()方法是稳定的")，并且sorted在功能上相似.但是，我找不到任何明确的说法.

I'm guessing it might be stable since the sort method on lists is guaranteed to be stable (Notes 9th point: "Starting with Python 2.3, the sort() method is guaranteed to be stable"), and sorted is functionally similar. However, I'm not able to find any definitive source that says so.

目的:在两个记录中主键相等的情况下，我需要基于主键和辅助键进行排序.如果保证sorted()是稳定的，那么我可以对辅助键进行排序，然后对主键进行排序，并获得所需的结果.

Purpose: I need to sort based on a primary key and also a secondary key in cases where the primary key is equal in both records. If sorted() is guaranteed to be stable, I can sort on the secondary key, then sort on the primary key and get the result I need.

PS:为避免引起混淆，我使用稳定"的含义是排序是稳定的，如果它保证不更改比较相等的元素的相对顺序".

PS: To avoid any confusion, I'm using stable in the sense of "a sort is stable if it guarantees not to change the relative order of elements that compare equal".

推荐答案

是的，该手册的目的确实是为了确保sorted是稳定的，并且确实使用与sort方法完全相同的算法.我的确意识到这些文件并不是100％清楚.总是很高兴地接受doc补丁！

Yes, the intention of the manual is indeed to guarantee that sorted is stable and indeed that it uses exactly the same algorithm as the sort method. I do realize that the docs aren't 100% clear about this identity; doc patches are always happily accepted!

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