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From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: sort
Message-ID: <1990Aug29.063639.15479@iwarp.intel.com>
Date: 29 Aug 90 06:36:39 GMT
References: <1990Aug21.202005.26275@uvaarpa.Virginia.EDU> <1990Aug21.224327.20194@iwarp.intel.com> <1990Aug22.111018.3329@comp.vuw.ac.nz> <MIKE.MCMANUS.90Aug28165252@mustang.FtCollins.NCR.com>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 36
In-Reply-To: Mike.McManus@FtCollins.NCR.com (Mike McManus)

In article <MIKE.MCMANUS.90Aug28165252@mustang.FtCollins.NCR.com>, Mike.McManus@FtCollins (Mike McManus) writes:
| Interestingly enuff, I had need for a similar sorting routine today, but with a
| twist: I want to sort the indices of an associative array that are of the form
| "A0, A1, A2, ..., A9, A10, ..."  Of course an alphabetic sort returns "A0, A10,
| A11, A19, ..., A1, ...", not what I want!  
| 
| Any simple solutions?  Thanks!

Well, two come to mind.  The first one is pretty trivial source code:

sub by_the_numbers_mostly { substr($a,1,999) > substr($b,1,999) ? 1 : -1; }

However, I haven't tested this for speed (it's doing a lot of work in
those substr's over and over and over again).  What you might want to
do is build a parallel array:

@foo=('A10'..'A19','A0'..'A9');  # not in order, for demo

grep(s/^.//,@fookey = @foo);

sub byfookey { $fookey[$a] > $fookey[$b] ? 1 : -1; }

@sortfoo = @foo[sort byfookey $[..$#foo];

print "@sortfoo";

For large arrays, I believe this would win.  For small arrays, the
first would probably win (I haven't tested that... if someone has a
few more minutes than me, go ahead and please let us know).

print "Just another Perl hacker,"
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
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