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lib/AI/NeuralNet/SOM/Rect.pm  view on Meta::CPAN

package AI::NeuralNet::SOM::Rect;

use strict;
use warnings;

use Data::Dumper;
use base qw(AI::NeuralNet::SOM);
use AI::NeuralNet::SOM::Utils;

=pod

=head1 NAME

AI::NeuralNet::SOM::Rect - Perl extension for Kohonen Maps (rectangular topology)

=head1 SYNOPSIS

  use AI::NeuralNet::SOM::Rect;
  my $nn = new AI::NeuralNet::SOM::Rect (output_dim => "5x6",
                                         input_dim  => 3);
  $nn->initialize;
  $nn->train (30, 
    [ 3, 2, 4 ], 
    [ -1, -1, -1 ],
    [ 0, 4, -3]);

  print $nn->as_data;

=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 string of the form "3x4" defining the X and the Y dimensions.

=back

Example:

    my $nn = new AI::NeuralNet::SOM::Rect (output_dim => "5x6",
                                           input_dim  => 3);

=cut

sub new {
    my $class = shift;
    my %options = @_;
    my $self = bless { %options }, $class;

    if ($self->{output_dim} =~ /(\d+)x(\d+)/) {
	$self->{_X} = $1 and $self->{_Y} = $2;
    } else {
	die "output dimension does not have format MxN";
    }
    if ($self->{input_dim} > 0) {
	$self->{_Z} = $self->{input_dim};
    } else {
	die "input dimension must be positive integer";
    }


    ($self->{_R}) = map { $_ / 2 } sort {$b <= $a } ($self->{_X}, $self->{_Y});          # radius
    $self->{_Sigma0} = $options{sigma0} || $self->{_R};                                  # impact distance, start value
    $self->{_L0} = $options{learning_rate} || 0.1;                                       # learning rate, start value
    return $self;
}

=pod

=head2 Methods

=cut

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->{_Y}-1) {
	    $self->{map}->[$x]->[$y] = &$get_from_stream;
	}
    }
}