#!/usr/bin/perl -w
use strict;
use Benchmark;

my $count = 500000;
my $line = "1!2!3!4!5!6!7!8!9";
my @arr = split /!/, $line;
my @exclude = (2,5..8);
my @exclude_lkup;
$exclude_lkup[$_] = 1 for @exclude;

sub ikegami
{
	my @tarr = @arr;
	my @filtered = map $tarr[$_], grep !$exclude_lkup[$_], 0..$#tarr;
}

sub injun
{
	my @tarr = @arr;
	@tarr[@exclude] = ();
	@tarr = grep $_, @tarr;
}

timethese (
  $count,
  {'Ikegami' => '&ikegami',
   'InjunJoel' => '&injun'}
);


##</code><code>##

Benchmark: timing 500000 iterations of Ikegami, InjunJoel...
   Ikegami: 16 wallclock secs (15.88 usr + 0.00 sys = 15.88 CPU) @ 31494.08/s (n=500000)
 InjunJoel: 10 wallclock secs ( 11.05 usr + 0.00 sys =  11.05 CPU) @ 45265.25/s (n=500000)