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lib/AI/NeuralNet/FastSOM/Hexa.pm  view on Meta::CPAN

package AI::NeuralNet::FastSOM::Hexa;

use strict;
use warnings;

use AI::NeuralNet::FastSOM;
our @ISA = qw/AI::NeuralNet::FastSOM/;

our $VERSION = '0.19';

sub radius   { shift->{_R} }
sub diameter { shift->{_X} }

sub as_data   { die 'not implemented' }
sub as_string { die 'not implemented' }

sub initialize {
    my $self = shift;
    my @data = @_;

    our $i = 0;
    my $get_from_stream = sub {
        $i = 0 if $i > $#data;
        return [ @{ $data[$i++] } ];  # cloning !
    } if @data;
    $get_from_stream ||= sub {
        return [ map { rand( 1 ) - 0.5 } 1..$self->{_Z} ];
    };

    for my $x (0 .. $self->{_X}-1) {
        for my $y (0 .. $self->{_X}-1) {
            $self->{map}->[$x]->[$y] = &$get_from_stream;
        }
    }
}

1;

__END__

=pod

=head1 NAME

AI::NeuralNet::FastSOM::Hexa - Perl extension for Kohonen Maps (hexagonal topology)

=head1 SYNOPSIS

  use AI::NeuralNet::FastSOM::Hexa;
  my $nn = new AI::NeuralNet::FastSOM::Hexa (output_dim => 6,
                                         input_dim  => 3);
  # ... see also base class AI::NeuralNet::FastSOM

=head1 INTERFACE

=head2 Constructor

The constructor takes the following arguments (additionally to those in
the base class):

=over

=item C<output_dim> : (mandatory, no default)

A positive, non-zero number specifying the diameter of the hexagonal. C<1>
creates one with a single hexagon, C<2> one with 4, C<3> one with 9. The
number plays the role of a diameter.

=back

Example:

    my $nn = new AI::NeuralNet::FastSOM::Hexa (output_dim => 6,
                                           input_dim  => 3);

=head2 Methods

=over

=item I<radius>

Returns the radius (half the diameter).

=item I<diameter>

Returns the diameter (= dimension) of the hexagon.

=item I<map>

I<$m> = I<$nn>->map

This method returns the 2-dimensional array of vectors in the grid
(as a reference to an array of references to arrays of vectors).

Example:

   my $m = $nn->map;
   for my $x (0 .. $nn->diameter -1) {
       for my $y (0 .. $nn->diameter -1){
           warn "vector at $x, $y: ". Dumper $m->[$x]->[$y];
       }
   }

This array represents a hexagon like this (ASCII drawing is so cool):