in reply to Re: Genesis of a sort routine
in thread Genesis of a sort routine

Here's a benchmark to backup the claim. Replacing the regex in the map with index gives even a slightly better result, but that effect is only minimal compared to eliminating the sort block (linear vs n log n). 
#!/usr/bin/perl

use strict;
use warnings;

use Benchmark qw /timethese cmpthese/;

my $elements = 1_000;
my $colon    =    50;
                  
our @array = map {$_ = crypt $_, sprintf "%02x" => rand 256;
                  substr $_, int rand length, 1, ":" if $colon < rand 
+100;
                  $_} 1 .. $elements;

our (@green, @dan, @abi1, @abi2);
    
cmpthese -10 => {
    greenFox => '@green = sort {(($a =~ /:/) <=> ($b =~ /:/)) || $a cm
+p $b}
                          @array',
   '3dan'    => '@dan   = sort {((index ($a, ":") >= 0) <=>
                                 (index ($b, ":") >= 0)) || $a cmp $b}
+ @array',
    abigail1 => '@abi1  = map  {substr $_ => 1}
                          sort
                          map  {/:/ ? "1$_" : "0$_"} @array',
    abigail2 => '@abi2  = map  {substr $_ => 1}
                          sort
                          map  {index ($_, ":") >= 0 ? "1$_" : "0$_"} 
+@array',
};


warn '@green != @dan',  "\n" if "@green" ne "@dan"; 
warn '@green != @abi1', "\n" if "@green" ne "@abi1";
warn '@green != @abi2', "\n" if "@green" ne "@abi2";
warn '@dan   != @abi1', "\n" if "@dan"   ne "@abi1";
warn '@dan   != @abi2', "\n" if "@dan"   ne "@abi2";
warn '@abi1  != @abi2', "\n" if "@abi1"  ne "@abi2";

__END__
          Rate greenFox     3dan abigail1 abigail2
greenFox 109/s       --     -16%     -54%     -56%
3dan     130/s      19%       --     -45%     -47%
abigail1 236/s     117%      82%       --      -4%
abigail2 246/s     126%      89%       4%       --

[download]
Abigail

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Re: Re: Genesis of a sort routine
by Anonymous Monk on Nov 06, 2003 at 14:30 UTC
    Adding this entry: 
        anon     => '@anon = (sort(grep!/:/,@array), sort(grep/:/,@array))
+',

    [download]

    To your benchmark code demonstrates a significant speed increase (and the 'grep only once' anonymous version seen previously is slightly faster still): 

    
           Rate greenFox     3dan abigail1 abigail2     anon
greenFox 26.2/s       --      -7%     -48%     -51%     -68%
3dan     28.2/s       8%       --     -44%     -48%     -65%
abigail1 50.7/s      94%      80%       --      -6%     -37%
abigail2 53.7/s     105%      91%       6%       --     -33%
anon     80.7/s     208%     186%      59%      50%       --

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In Section Meditations