Re: Re: Difference between tr// and s///?

Your benchmark is flawed. On the first iteration of the testing, your $toto variable has all of its '+' characters changed to ' ' (space) characters. After that, all subsequent iterations and tests are acting upon the "fixed" string, and thus, they basically have no more work to do other than their own internal overhead.

For your benchmark to gain validity, you'll need to make a copy of $toto, to act upon, inside each test, so that the original $toto is always in its original condition. Or declare and define $toto inside of each individual sub being tested.

Dave

Comment on Re: Re: Difference between tr// and s///?

Replies are listed 'Best First'.
Re: Re: Re: Difference between tr// and s///? by Limbic~Region (Chancellor) on Feb 06, 2004 at 16:45 UTC
davido, You are correct as the following modified code shows: #!/usr/bin/perl use strict; use warnings; use Benchmark qw(:all); my $length = (int rand 100) + 100; my @char = ( 'a' .. 'c' , '+' , 'd' .. 'f' ); my $string; $string .= $char[ int rand 7 ] for 0 .. $length ; my $count = -5; my $results = timethese ( $count, { 'transliterate' => sub { my $foo = $string; $foo =~ tr/ ++/ /; }, 'substitution' => sub { my $bar = $string; $bar =~s/\+ +/ /g; }, }, 'none' ); cmpthese( $results ) ; __END__ Rate substitution transliterate substitution 124624/s -- -84% transliterate 784349/s 529% -- [download] Cheers - L~R	[reply] [d/l]

Replies are listed 'Best First'.

Re: Re: Re: Difference between tr// and s///?
by Limbic~Region (Chancellor) on Feb 06, 2004 at 16:45 UTC

davido

#!/usr/bin/perl
use strict;
use warnings;

use Benchmark qw(:all);

my $length = (int rand 100) + 100;
my @char = ( 'a' .. 'c' , '+' , 'd' .. 'f' );
my $string;

$string .= $char[ int rand 7 ] for  0 .. $length ;
my $count = -5;


my $results = timethese ( $count,
           {
               'transliterate' => sub { my $foo = $string; $foo =~ tr/
++/ /; },
               'substitution' => sub {  my $bar = $string; $bar =~s/\+
+/ /g; },
           },
           'none'
       );
cmpthese( $results ) ;
__END__
                  Rate  substitution transliterate
substitution  124624/s            --          -84%
transliterate 784349/s          529%            --
[download]

L~R

[reply]
[d/l]