Re: Sorting through a rollover

I learned this from ysth other day:

use strict; 
use warnings;

my @num = qw( 00002 00003 00001 99999 99998 );

@num = sort {  
           ( $a < 50000 ) <=> ( $b < 50000 ) || 
           $a <=> $b 
       } @num;

print "sorted: @num \n";

#  sorted: 99998 99999 00001 00002 00003
[download]

Comment on Re: Sorting through a rollover Download Code

Replies are listed 'Best First'.
Re^2: Sorting through a rollover by RazorbladeBidet (Friar) on Feb 10, 2005 at 17:56 UTC
if `my @num = qw( 49998 49999 50000 50001 50002 500003)` you get `sorted: 50000 50001 50002 500003 49998 49999` There's got to be a link between the number shown on the page. Update How about `sort { abs( $a - $b ) > 200 ? $b <=> $a : $a <=> $b }` [download] Y'know I just thought of something - looks like you're reading from a log of some sort why would you have to sort at all? Is it even necessary? (Just checking)	[reply] [d/l] [select]
Re^3: Sorting through a rollover by Roy Johnson (Monsignor) on Feb 10, 2005 at 20:30 UTC
Or slightly more compactly (using trinary math instead of the trinary operator): `(abs($a - $b) <=> $max_spread) * ($b <=> $a)` [download] where `$max_spread` is the maximum range you expect your numbers to cover before wrapping. 50_000 might be a better choice than 200. Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]
Re^4: Sorting through a rollover by RazorbladeBidet (Friar) on Feb 10, 2005 at 20:40 UTC
The 200 was based upon the fact that he's showing 200 messages. either way, I think as long as it's less than the possible number of id's, it'll be ok (or maybe less than half?)	[reply]