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Re: Did the sort do anything?

From Joshua Cranmer <Pidgeot18@verizon.invalid>
Newsgroups comp.lang.java.programmer
Subject Re: Did the sort do anything?
Date 2011-05-12 10:40 -0400
Organization A noiseless patient Spider
Message-ID <iqgrhp$fh7$1@dont-email.me> (permalink)
References <eskis656eeu0of5f5do1ogdpfbdau3d06i@4ax.com> <9303hcFq0nU1@mid.individual.net>

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On 05/11/2011 02:40 PM, Robert Klemme wrote:
> Btw, couldn't option 3 be tricky? Depending on the sorting algorithm
> things might be moved around but the final order might be the same as
> before. Not that this would be desirable but I am pretty sure there are
> sorting algorithms which have this property (probably quicksort).

The term you are looking for is the stability of the sort. A stable sort 
preserves the order of equally-compared object; unstable sorts do not. 
Of the major sorts, heapsort and quicksort are the only sorts which are 
unstable, although a bad of implementation of any stable sort could be 
unstable. Wikipedia claims that quicksort can be implemented stably, but 
that comes at an O(n) space price.

Java uses quicksort for primitive types in Arrays.sort and mergesort for 
reference types: since you can't distinguish two equal primitive types, 
you can't tell that quicksort isn't stable.

-- 
Beware of bugs in the above code; I have only proved it correct, not 
tried it. -- Donald E. Knuth

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Thread

Did the sort do anything? Roedy Green <see_website@mindprod.com.invalid> - 2011-05-10 08:06 -0700
  Re: Did the sort do anything? markspace <-@.> - 2011-05-10 08:48 -0700
    Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-14 15:33 +1200
      Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-14 08:56 -0400
        Re: Did the sort do anything? Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-05-14 13:54 +0000
          Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-15 11:16 +1200
      Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-14 23:24 -0400
        Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-15 11:20 +0100
          Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-15 07:00 -0400
            Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-15 15:09 +0100
              Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-16 14:28 +1200
                Re: Did the sort do anything? Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-05-15 22:38 -0400
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-16 19:11 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 03:47 -0400
                Re: Did the sort do anything? markspace <-@.> - 2011-05-16 14:14 -0700
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-15 22:40 -0400
                Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-16 21:31 +0100
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-17 09:12 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 17:24 -0400
                Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-17 13:26 +0100
          Re: Did the sort do anything? markspace <-@.> - 2011-05-15 04:56 -0700
            Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-15 15:12 +0100
              Re: Did the sort do anything? markspace <-@.> - 2011-05-15 07:52 -0700
          Re: Did the sort do anything? Michael Wojcik <mwojcik@newsguy.com> - 2011-05-18 11:14 -0400
            Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-18 13:02 -0400
            Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-20 18:49 +1200
              Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-20 00:06 -0700
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-20 22:37 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-20 07:09 -0400
  Re: Did the sort do anything? Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-05-10 16:11 +0000
  Re: Did the sort do anything? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-05-10 21:26 +0200
    Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-11 21:38 +0100
      Re: Did the sort do anything? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-05-11 23:27 +0200
      Re: Did the sort do anything? Roedy Green <see_website@mindprod.com.invalid> - 2011-05-13 07:40 -0700
        Re: Did the sort do anything? Spock <spock@starfleet.ufp> - 2011-05-13 16:56 -0400
        Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-15 13:58 +1200
          Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-14 23:27 -0400
  Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-11 20:40 +0200
    Re: Did the sort do anything? Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-05-12 10:40 -0400
      Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-13 03:50 -0700
      Re: Did the sort do anything? Roedy Green <see_website@mindprod.com.invalid> - 2011-05-13 07:46 -0700
        Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-16 14:32 +1200
          Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-15 19:50 -0700
            Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-16 17:57 +1200
              Re: Did the sort do anything? "javax.swing.JSnarker" <gharriman@boojum.mit.edu> - 2011-05-16 03:35 -0400
              Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 03:44 -0400
              Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-16 03:53 -0700
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-17 00:02 +1200
                Re: Did the sort do anything? "javax.swing.JSnarker" <gharriman@boojum.mit.edu> - 2011-05-16 08:05 -0400
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-17 09:12 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 17:32 -0400
                Re: Did the sort do anything? thoolen <thoolen@tholenbot.thorium> - 2011-05-16 18:09 -0400
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 10:02 -0400
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-16 07:16 -0700
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-17 09:11 +1200
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-16 15:00 -0700
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-16 21:08 -0400
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-17 19:11 +1200
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-17 02:34 -0700
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-17 07:19 -0400
                [OT] Naming conventions. Was: Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-17 06:52 -0700
                Re: Naming conventions. Was: Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-18 01:22 -0700
                Re: Naming conventions. Was: Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-18 03:42 -0700
                Re: Naming conventions. Was: Re: Did the sort do anything? RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-05-18 11:53 +0100
                Re: Naming conventions. Was: Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-18 13:07 -0400
                Re: Naming conventions. Was: Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-18 10:37 -0700
                Re: Naming conventions. Was: Re: Did the sort do anything? Heike Svensson <hsvensson.1093x1_q@hotmail.nospam.com.please> - 2011-05-19 01:29 -0400
                Re: Naming conventions. Was: Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-19 08:28 +0200
                Re: Naming conventions. Was: Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-19 08:50 -0400
                OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-05-23 10:25 +0100
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-23 09:05 -0400
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-05-23 17:17 +0100
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-23 14:43 -0400
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? Steve Sobol <sjsobol@JustThe.net> - 2011-05-23 08:27 -0700
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-05-23 17:39 +0100
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re:   Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-23 19:16 +0200
                Re: OT: National stereotypes. Was Re: Naming conventions. Was: Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-23 14:47 -0400
                Re: Did the sort do anything? Boojum <boojum42@gmai1.c0m> - 2011-05-18 07:19 -0400
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-20 18:46 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-20 07:10 -0400
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-17 07:16 -0400
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-17 06:56 -0700
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-20 18:46 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-20 07:11 -0400
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-20 05:00 -0700
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-20 05:20 -0700
                Re: Did the sort do anything? Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-05-21 09:56 +1200
                Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-20 18:12 -0400
                Re: Did the sort do anything? Patricia Shanahan <pats@acm.org> - 2011-05-20 21:26 -0700
                Re: Did the sort do anything? Gheerax IV <gheerax.4@gmail.invalid> - 2011-05-17 06:58 +0000
                Re: Did the sort do anything? Unitary Matrix <umatrix668@gmail.com> - 2011-05-17 00:13 -0700
                Re: Did the sort do anything? markspace <-@.> - 2011-05-17 07:41 -0700
    Re: Did the sort do anything? Roedy Green <see_website@mindprod.com.invalid> - 2011-05-13 07:42 -0700
      Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-13 21:28 +0200
  Re: Did the sort do anything? Tom Anderson <twic@urchin.earth.li> - 2011-05-11 21:32 +0100

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