From: Robert Klemme <shortcutter@...>
Date: 2013-06-18T15:01:53+09:00
Subject: Re: Compare and sort one array according to another.

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On Mon, Jun 17, 2013 at 11:35 PM, Douglas Seifert <doug@dseifert.net> wrote:

> You have said that the size of your two arrays is small, so the fact that
> the find_index based solution is o(n^2) probably doesn't matter.
>

Yes, that's what I was figuring.  Your analysis is spot on.


>  For kicks, a o(n) solution compared to the o(n^2) solution here:
>
> https://gist.github.com/seifertd/5800639
>
> It involves precomputing a lookup index for the data you need to sort.
>

Your "gen_lookup:" is exactly what I'd did for larger arrays.

Kind regards

robert


-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><br><div class=3D"gmail=
_quote">On Mon, Jun 17, 2013 at 11:35 PM, Douglas Seifert <span dir=3D"ltr"=
>&lt;<a href=3D"mailto:doug@dseifert.net" target=3D"_blank">doug@dseifert.n=
et</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><div dir=3D"ltr">You have said that the size=
 of your two arrays is small, so the fact that the find_index based solutio=
n is o(n^2) probably doesn&#39;t matter. </div>
</blockquote><div><br></div><div style>Yes, that&#39;s what I was figuring.=
 =A0Your analysis is spot on.</div><div>=A0</div><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex">
<div dir=3D"ltr">=A0For kicks, a o(n) solution compared to the o(n^2) solut=
ion here:<br>
<br><a href=3D"https://gist.github.com/seifertd/5800639" target=3D"_blank">=
https://gist.github.com/seifertd/5800639</a><div><br></div><div>It involves=
 precomputing a lookup index for the data you need to sort.</div></div></bl=
ockquote>
<div><br></div><div style>Your &quot;gen_lookup:&quot; is exactly what I&#3=
9;d did for larger arrays.</div><div style><br></div><div style>Kind regard=
s</div><div style><br></div><div style>robert</div></div><br clear=3D"all">
<div><br></div>-- <br>remember.guy do |as, often| as.you_can - without end<=
br><a href=3D"http://blog.rubybestpractices.com/">http://blog.rubybestpract=
ices.com/</a>
</div></div>

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