#!/usr/bin/perl --
use strict;
use warnings;
use Benchmark qw(cmpthese);
print "\n$]\n";
our $data;
for my $range ( 1_000 , 2_000 , 10_000 , 100_000 ){
    $data = join '',map { ( qw' T A C G ' )[ $_ % 4 ] } 0 .. $range;
    print "\n$range\n";
    cmpthese (-3, {
        SplitAssign => \&SplitAssign,
        SplitRegex => \&SplitRegex,
        Substitution => \&Substitution,
    });
    print "##" x 33, "\n\n";
}
sub SplitAssign {
    my @data = split //, $data;
    for my $char ( @data ){
        if( $char eq 'T' ){ $char = 'G'; }
        elsif( $char eq 'A' ){ $char = 'T'; }
        elsif( $char eq 'C' ){ $char = 'A'; }
        elsif( $char eq 'G' ){ $char = 'C'; }
    }
    my $newData = join '', @data;
    return;
}
sub SplitRegex {
    my @data = split //, $data;
    for my $char ( @data ){
        if( $char eq 'T' ){ $char =~ s/T/G/; }
        elsif( $char eq 'A' ){ $char =~ s/A/T/; }
        elsif( $char eq 'C' ){ $char =~ s/C/A/; }
        elsif( $char eq 'G' ){ $char =~ s/G/C/; }
    }
    my $newData = join '', @data;
    return;
}
sub Substitution {
    my $newData = $data;
    $newData =~ s/(.)/
        my $char = $1;
        if( $char eq 'T' ){ $char = 'G'; }
        elsif( $char eq 'A' ){ $char = 'T'; }
        elsif( $char eq 'C' ){ $char = 'A'; }
        elsif( $char eq 'G' ){ $char = 'C'; }
        $char;
    /ge;
    return;
}
__END__
[download]

5.012002

1000
              Rate Substitution   SplitRegex  SplitAssign
Substitution 299/s           --          -9%         -37%
SplitRegex   329/s          10%           --         -31%
SplitAssign  478/s          60%          45%           --
##################################################################


2000
              Rate Substitution   SplitRegex  SplitAssign
Substitution 147/s           --          -6%         -34%
SplitRegex   157/s           7%           --         -30%
SplitAssign  224/s          53%          43%           --
##################################################################


10000
               Rate   SplitRegex Substitution  SplitAssign
SplitRegex   27.8/s           --          -3%         -25%
Substitution 28.6/s           3%           --         -23%
SplitAssign  37.2/s          34%          30%           --
##################################################################


100000
               Rate   SplitRegex  SplitAssign Substitution
SplitRegex   1.91/s           --         -16%         -28%
SplitAssign  2.29/s          20%           --         -13%
Substitution 2.64/s          38%          15%           --
##################################################################
[download]