Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #68366

blist in standard library (was Re: Balanced trees)

Path csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed2a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path <python-python-list@m.gmane.org>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.000
X-Spam-Evidence '*H*': 1.00; '*S*': 0.00; 'from:addr:yahoo.co.uk': 0.04; 'third-party': 0.04; 'tree': 0.05; 'assignment': 0.07; 'explicit': 0.07; 'pypi': 0.07; 'removes': 0.07; 'curve': 0.09; 'exist,': 0.09; 'happens.': 0.09; 'inclusion': 0.09; 'input,': 0.09; 'lawrence': 0.09; 'merging': 0.09; 'pep': 0.09; 'preferable': 0.09; 'promising': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'rejected': 0.09; 'structure,': 0.09; 'python': 0.11; 'language.': 0.14; 'collections': 0.16; 'containers': 0.16; 'deletion': 0.16; 'doubles': 0.16; 'fifo': 0.16; 'foolishly': 0.16; 'jumps': 0.16; 'pruning': 0.16; 'rarely': 0.16; 'rather,': 0.16; 'reason.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'slicing,': 0.16; 'sorts': 0.16; 'subject:library': 0.16; 'trees:': 0.16; 'url:peps': 0.16; 'essential': 0.16; 'appropriate': 0.16; 'url:)': 0.16; 'language': 0.16; 'wrote:': 0.18; 'library': 0.18; 'looked': 0.18; 'all,': 0.19; '(but': 0.19; 'unlike': 0.19; 'solution.': 0.20; 'fit': 0.20; 'written': 0.21; 'header:User-Agent:1': 0.23; 'finally,': 0.24; 'module,': 0.24; 'replace': 0.24; 'url:dev': 0.24; 'java': 0.24; '---': 0.24; "i've": 0.25; 'second': 0.26; 'skip:" 20': 0.27; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'specifically': 0.29; "we'd": 0.29; 'raise': 0.29; 'scanned': 0.29; "doesn't": 0.30; '(like': 0.30; 'raymond': 0.30; 'especially': 0.30; '(which': 0.31; 'went': 0.31; 'code': 0.31; 'equivalent.': 0.31; 'factor': 0.31; 'fast.': 0.31; 'idea,': 0.31; 'libraries': 0.31; 'loads': 0.31; 'stories.': 0.31; 'lists': 0.32; 'selection': 0.32; 'regular': 0.32; 'url:python': 0.33; 'cases': 0.33; 'copying': 0.34; "i'd": 0.34; 'could': 0.34; 'problem': 0.35; 'operations': 0.35; 'but': 0.35; 'add': 0.35; 'there': 0.35; 'really': 0.36; 'instances': 0.36; 'largely': 0.36; 'library.': 0.36; 'module.': 0.36; 'much.': 0.36; 'reflect': 0.36; 'useful': 0.36; 'url:org': 0.36; 'so,': 0.37; 'two': 0.37; 'list': 0.37; 'list.': 0.37; 'performance': 0.37; 'sometimes': 0.38; 'branch': 0.38; 'needed': 0.38; 'whatever': 0.38; 'to:addr:python-list': 0.38; 'viruses': 0.61; 'success': 0.61; 'protection': 0.63; 'our': 0.64; 'become': 0.64; 'more': 0.64; 'different': 0.65; 'chance': 0.65; 'linked': 0.65; 'effectively': 0.66; 'worth': 0.66; 'believe': 0.68; 'benefit': 0.68; 'advantages': 0.68; 'antivirus': 0.68; 'nobody': 0.68; 'real-world': 0.68; 'superior': 0.69; 'home.': 0.72; 'further,': 0.74; 'obvious': 0.74; 'balanced': 0.84; 'misses': 0.84; 'much,': 0.84; 'pocket': 0.84; 'points,': 0.84; 'python-dev': 0.84; 'scarily': 0.84; 'demand': 0.91; 'good,': 0.91; 'obvious,': 0.91; 'url:ru': 0.98
X-Injected-Via-Gmane http://gmane.org/
To python-list@python.org
From Mark Lawrence <breamoreboy@yahoo.co.uk>
Subject blist in standard library (was Re: Balanced trees)
Date Sat, 15 Mar 2014 12:31:26 +0000
References <lennh4$kpm$1@cabale.usenet-fr.net> <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com> <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com> <mailman.7473.1393598638.18130.python-list@python.org> <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net> <mailman.7920.1394252278.18130.python-list@python.org> <87eh2d3x8h.fsf_-_@elektro.pacujo.net> <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com> <lffv32$mqo$1@ger.gmane.org> <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
Mime-Version 1.0
Content-Type text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding 8bit
X-Gmane-NNTP-Posting-Host host-78-147-28-104.as13285.net
User-Agent Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
In-Reply-To <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
X-Antivirus avast! (VPS 140315-0, 15/03/2014), Outbound message
X-Antivirus-Status Clean
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.15
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.8155.1394886716.18130.python-list@python.org> (permalink)
Lines 98
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1394886716 news.xs4all.nl 2870 [2001:888:2000:d::a6]:53482
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:68366

Show key headers only | View raw

On 15/03/2014 01:13, Joshua Landau wrote:
> On 8 March 2014 20:37, Mark Lawrence <breamoreboy@yahoo.co.uk> wrote:
>> I've found this link useful http://kmike.ru/python-data-structures/
>>
>> I also don't want all sorts of data structures added to the Python library.
>> I believe that there are advantages to leaving specialist data structures on
>> pypi or other sites, plus it means Python in a Nutshell can still fit in
>> your pocket and not a 40 ton articulated lorry, unlike the Java equivalent.
>
> The thing we really need is for the blist containers to become stdlib
> (but not to replace the current list implementation). The rejected PEP
> (http://legacy.python.org/dev/peps/pep-3128/) misses a few important
> points, largely in how the "log(n)" has a really large base:
> random.choice went from 1.2µs to 1.6µs from n=1 to n=10⁸, vs 1.2µs for
> a standard list.
>
> Further, it's worth considering a few advantages:
>
> * copy is O(1), allowing code to avoid mutation by just copying its
> input, which is good practice.
>
> * FIFO is effectively O(1), as the time just about doubles from n=1 to
> n=10⁸ so will never actually branch that much. There is still a speed
> benefit of collections.deque, but it's much, much less significant.
> This is very useful when considering usage as a multi-purpose data
> structure, and removes demand for explicit linked lists (which have
> foolishly been reimplemented loads of times).
>
> * It reduces demand for trees:
>      * There are efficient implementations of sortedlist, sortedset and
> sorteddict.
>      * Slicing, slice assignment and slice deletion are really fast.
>      * Addition of lists is sublinear. Instead of
> "list(itertools.chain(...))", one can add in a loop and end up
> *faster*.
>
> I think blist isn't very popular not because it isn't really good, but
> because it isn't a specialised structure. It is, however, almost there
> for almost every circumstance. This can help keep the standard library
> clean, especially of tree data structures.
>
> Here's what we kill:
>
> * Linked lists and doubly-linked lists, which are scarily popular for
> whatever reason. Sometimes people claim that collections.deque isn't
> powerful enough for whatever they want, and blist will almost
> definitely sate those cases.
>
> * Balanced trees, with blist.sortedlist. This is actually needed right now.
>
> * Poor performance in the cases where a lot of list merging and pruning happens.
>
> * Most uses of bisect.
>
> * Some instances where two data structures are used in parallel in
> order to keep performance fast on disparate operations (like `x in y`
> and `y[i]`).
>
> Now, I understand there are downsides to blist. Particularly, I've
> looked through the "benchmarks" and they seem untruthful. Further,
> we'd need a maintainer. Finally, nobody jumps at blists because
> they're rarely the obvious solution. Rather, they attempt to be a
> different general solution. Hopefully, though, a stdlib inclusion
> could make them a lot more obvious, and support in some current
> libraries could make them feel more at home.
>
> I don't know whether this is a good idea, but I do feel that it is
> more promising and general than having a graph in the standard
> library.
>

I'd raise this on python-dev or python ideas as a result of reading PEP 
3128.  Specifically the second paragraph states Raymond Hettinger's sage 
advice:-

"Depending on its success as a third-party module, it still has a chance 
for inclusion in the collections module. The essential criteria for that 
is whether it is a superior choice for some real-world use cases. I've 
scanned my own code and found no instances where BList would have been 
preferable to a regular list. However, that scan has a selection bias 
because it doesn't reflect what I would have written had BList been 
available. So, after a few months, I intend to poll comp.lang.python for 
BList success stories. If they exist, then I have no problem with 
inclusion in the collections module. After all, its learning curve is 
near zero -- the only cost is the clutter factor stemming from 
indecision about the most appropriate data structure for a given task."

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: Tuples and immutability Duncan Booth <duncan.booth@invalid.invalid> - 2014-03-07 09:33 +0000
  Re: Tuples and immutability Ben Finney <ben+python@benfinney.id.au> - 2014-03-07 22:04 +1100
  Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-03-07 22:11 +1100
  Re: Tuples and immutability Peter Otten <__peter__@web.de> - 2014-03-07 12:38 +0100
  Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-03-07 22:45 +1100
  Re: Tuples and immutability Alister <alister.ware@ntlworld.com> - 2014-03-07 11:51 +0000
    Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-07 11:23 -0700
  Re: Tuples and immutability Roy Smith <roy@panix.com> - 2014-03-07 08:37 -0500
  Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-08 15:17 +1300
    Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-07 21:17 -0700
      Balanced trees (was: Re: Tuples and immutability) Marko Rauhamaa <marko@pacujo.net> - 2014-03-08 10:34 +0200
        Re: Balanced trees (was: Re: Tuples and immutability) Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-08 04:03 -0700
          Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-08 13:26 +0200
        Re: Balanced trees (was: Re: Tuples and immutability) Dan Stromberg <drsalists@gmail.com> - 2014-03-08 11:58 -0800
        Re: Balanced trees Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-03-08 20:37 +0000
          Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-08 23:21 +0200
            Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-08 17:22 -0500
              Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-09 11:17 +0200
            Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-08 17:31 -0800
              Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-09 11:27 +0200
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-09 14:20 -0700
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-09 23:32 +0200
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-09 14:37 -0700
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-09 23:43 +0200
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-09 15:08 -0700
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-10 00:24 +0200
                Re: Balanced trees Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-09 18:04 -0600
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-10 03:24 +0000
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-10 03:24 +0000
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-10 08:16 +0200
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-10 08:53 +0000
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-10 11:41 +0200
                Re: Balanced trees Ned Batchelder <ned@nedbatchelder.com> - 2014-03-10 06:57 -0400
                Re: Balanced trees Rustom Mody <rustompmody@gmail.com> - 2014-03-10 09:01 -0700
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-11 02:02 +0000
                Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-10 22:20 -0400
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 13:29 +1100
                Re: Balanced trees Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-03-10 09:51 +0000
                Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-10 09:59 -0400
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 03:20 +1100
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 03:24 +1100
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-10 19:08 +0200
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 04:17 +1100
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-10 19:34 +0200
                Re: Balanced trees Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-13 12:40 -0600
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-13 23:57 +0000
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-13 20:12 -0700
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-14 05:02 +0000
                Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-10 19:24 -0400
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 10:27 +1100
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-11 01:26 +0000
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 12:45 +1100
                Re: Balanced trees Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-10 21:38 -0600
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 15:28 +1100
                Re: Balanced trees "Rhodri James" <rhodri@wildebst.org.uk> - 2014-03-12 00:57 +0000
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-11 12:12 +0200
                Re: Balanced trees alex23 <wuwei23@gmail.com> - 2014-03-12 10:13 +1000
                Re: Balanced trees Alister <alister.ware@ntlworld.com> - 2014-03-11 09:25 +0000
                Re: Balanced trees Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2014-03-12 10:08 +0100
                Re: Balanced trees Tim Chase <python.list@tim.thechases.com> - 2014-03-10 11:33 -0500
                Re: Balanced trees Chris Angelico <rosuav@gmail.com> - 2014-03-11 03:39 +1100
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-10 18:05 -0700
                Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-10 22:13 -0400
                Re: Balanced trees Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-03-10 19:57 -0400
        Re: Balanced trees Joshua Landau <joshua@landau.ws> - 2014-03-15 01:13 +0000
          Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-18 00:05 +0200
            Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-18 12:26 -0700
              Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-18 22:55 +0200
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-18 14:45 -0700
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 00:03 +0200
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-18 15:21 -0700
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 01:11 +0200
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-19 01:15 +0000
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 10:49 +0200
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-19 13:42 +0000
                Re: Balanced trees Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 15:54 +0200
                Re: Balanced trees Roy Smith <roy@panix.com> - 2014-03-19 10:06 -0400
                Re: Balanced trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-19 01:15 +0000
                Re: Balanced trees Ethan Furman <ethan@stoneleaf.us> - 2014-03-19 08:15 -0700
                Re: Balanced trees "Rhodri James" <rhodri@wildebst.org.uk> - 2014-03-20 02:16 +0000
                Re: Balanced trees Dan Stromberg <drsalists@gmail.com> - 2014-03-19 19:34 -0700
                Re: Balanced trees Chris Kaynor <ckaynor@zindagigames.com> - 2014-03-18 18:02 -0700
            Re: Balanced trees Daniel Stutzbach <stutzbach@google.com> - 2014-03-18 13:18 -0700
        blist in standard library  (was Re: Balanced trees) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-03-15 12:31 +0000
        Re: Balanced trees Daniel Stutzbach <stutzbach@google.com> - 2014-03-17 14:16 -0700
        Re: Balanced trees Joshua Landau <joshua@landau.ws> - 2014-03-18 00:08 +0000
        Re: Balanced trees Daniel Stutzbach <stutzbach@google.com> - 2014-03-17 18:01 -0700
        Re: Balanced trees Joshua Landau <joshua@landau.ws> - 2014-03-18 07:46 +0000
      Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-09 13:40 +1300
        Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-08 19:39 -0700
          Re: Tuples and immutability Marko Rauhamaa <marko@pacujo.net> - 2014-03-09 11:35 +0200
          Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-10 11:03 +1300
            Re: Tuples and immutability Terry Reedy <tjreedy@udel.edu> - 2014-03-09 19:00 -0400
            Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-09 17:42 -0600
              Re: Tuples and immutability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-10 02:37 +0000
                Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-10 02:35 -0600
                Re: Tuples and immutability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-10 09:13 +0000
                Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-11 18:15 +1300
              Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-11 18:03 +1300
                Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-11 04:39 -0600
                Re: Tuples and immutability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-11 16:46 +0000
                Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-12 10:23 +1300
                Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-11 17:06 -0600
                Re: Tuples and immutability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-12 23:20 +0000
                Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-12 19:35 -0600
                Re: Tuples and immutability Terry Reedy <tjreedy@udel.edu> - 2014-03-12 22:09 -0400
      Re: Tuples and immutability Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-09 13:45 +1300
        Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-08 19:55 -0700

csiph-web