Re: split n characters into n chunks

[John W. Krahn]

Shawn H Corey wrote:

John W. Krahn wrote:

$ perl -le'
my $word = "thequickbrown";
my $subsets = 3;
print for $word =~ /(?=(.{$subsets}))/g;

Getting up there but substr is still the fastest.

#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;

# Make Data::Dumper pretty
$Data::Dumper::Sortkeys = 1;
$Data::Dumper::Indent   = 1;

# Set maximum depth for Data::Dumper, zero means unlimited
$Data::Dumper::Maxdepth = 0;

my $Testing = $ARGV[0] || 0;
use Benchmark qw(:all);

my $word = "thequickbrown";
my $size = 3;

if( $Testing ){
  via_arrays();
  via_substr();
  via_unpack();
  via_match();
  via_match2();
}else{
  cmpthese( 50_000, {
    'via arrays' => \&via_arrays,
    'via substr' => \&via_substr,
    'via unpack' => \&via_unpack,
    'via match'  => \&via_match,
    'via match2' => \&via_match2,
  });
}


sub via_arrays {
  my @array = split //, $word;
  my $max = @array - $size;
  my @list = ();
  for my $i ( 0 .. $max ){
    push @list, join '', @array[ $i .. $i+$size-1 ];
  }
  # print Dumper \...@list;  #for testing only
}

sub via_substr {
  my $max = length( $word ) - $size;
  my @list = ();
  for my $i ( 0 .. $max ){
    push @list, substr( $word, $i, $size );
  }
  # print Dumper \...@list;  #for testing only
}

sub via_unpack {
  my $max = length( $word ) - $size;
  my @list = ();
  for my $i ( 0 .. $max ){
    push @list, (unpack( "A${i}A$size", $word ))[1];
  }
  # print Dumper \...@list;  #for testing only
}

sub via_match {
  my @list = ();
  push @list, substr( $word, $-[0], 3 )
    while $word =~ /.(?=..)/g;
  # print Dumper \...@list;  #for testing only
}

sub via_match2 {
  my @list = ();
  push @list, $_ for $word =~ /(?=(.{$size}))/g;

Why the for loop?

  my @list = $word =~ /(?=(.{$size}))/g;

  # print Dumper \...@list;  #for testing only
}

John
--
The programmer is fighting against the two most
destructive forces in the universe: entropy and
human stupidity.               -- Damian Conway

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