Re: Matching simple patterns - is there a faster way?

[flexvault]

mrguy123,

I benchmarked the code replacing the 'print' with '{ }':

           Rate index regex
regex 1562500/s    --  -34%
index 2380952/s  52%    --

Your not testing print, are you?

What is funny, is that I ran the code 3 times, and the exact same result occurred all 3 times. I usually take the middle one!

[mrguy123]

Hi, please see my benchmark test

use strict;
use Benchmark qw(cmpthese);

# A big, sorted list (475254 elements)
my @list = ('a'..'zzzz');
##Put the list into a string

my $string = join(/ /, @list);

$string .= "\n";

cmpthese(0, {
       # Looking for a random item in @list with grep
        index => sub {
                # A random element in the list
                my $pattern = 'fqsu  fqsv  fqsw  fqsx  fqsy';
                my $result = index($string, $pattern);

        },
        # Looking for a random item in @list linearly (with foreach)
        regex  => sub {
                my $pattern = 'fqsu  fqsv  fqsw  fqsx  fqsy';
                $string =~ /$pattern/;
        },
    }

);

I also did another test where I read a proper HTML file and received similar results. Can you please tell me what you did different?



---

Everybody seems to think I'm lazy
I don't mind, I think they're crazy

[flexvault]

mrguy123,

As requested ( I typed this in from the code ):

sub index
{  if ( index('yabba dabba doo','abba' ) >= 0 ) { }
}

sub regex
{   $_ = 'yabba dabba doo';
    if ( /abba/ ) { }
}

cmpthese ( 500_000, 
   {  regex => sub { &regex },
      index => sub { &index },
   },
 );

I have found 'index' usually faster than 'regex' in this type of situation, but 'regex' has more power when needed.

Regards...Ed

[mrguy123]

Hi flexvault, I am assuming you did the benchmark on the 'yabba dabba doo' example, which makes perfect sense because that is what I posted.
However, the real data is much larger and that may cause the difference in the benchmark
You can see my code example below for regex/index matching with larger amount of data