X-Received: by 10.236.17.234 with SMTP id j70mr15632268yhj.26.1408382300956; Mon, 18 Aug 2014 10:18:20 -0700 (PDT)
X-Received: by 10.50.79.201 with SMTP id l9mr11672igx.5.1408382300816; Mon, 18 Aug 2014 10:18:20 -0700 (PDT)
Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!m5no907560qaj.0!news-out.google.com!aw9ni1931igc.0!nntp.google.com!r2no2322288igi.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.python
Date: Mon, 18 Aug 2014 10:18:20 -0700 (PDT)
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=140.113.69.236; posting-account=eLmTSwoAAAA5GT-zoD7dCLRZUnwvEDUD
NNTP-Posting-Host: 140.113.69.236
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <51dfbe9b-f6e0-4532-bc2d-e7ce2fc282b5@googlegroups.com>
Subject: efficient partial sort in Python ?
From: Chiu Hsiang Hsu <wdv4758h@gmail.com>
Injection-Date: Mon, 18 Aug 2014 17:18:20 +0000
Content-Type: text/plain; charset=ISO-8859-1
Xref: csiph.com comp.lang.python:76495

I know that Python use Timsort as default sorting algorithm and it is efficient,
but I just wanna have a partial sorting (n-largest/smallest elements).

In the current state, I can only find this kind of functions from heapq,
but it's too slow for this problem,
the pure c sorted function can easily beat heapq.nlargest even though it sort all the elements.

I think it would be better if we have an effeicient partial sorting function,
maybe it could be like this : partial_sorted(data, n), data.partial_sort(n)

Does anyone have any more information for partial sorting ?

Btw, C++ has a partial_sort function in <algorithm>, but I don't know what algorithm it really use.