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package AI::NeuralNet::Hopfield;

use v5.10;
use strict;
use warnings;
use Moose;
use Math::SparseMatrix;


=head1 NAME

AI::NeuralNet::Hopfield - A simple Hopfiled Network Implementation.

=head1 VERSION

Version 0.1

=cut

our $VERSION = '0.1';

has 'matrix' => ( is => 'rw', isa => 'Math::SparseMatrix');

has 'matrix_rows'   => ( is => 'rw', isa => 'Int');

has 'matrix_cols'   => ( is => 'rw', isa => 'Int');

sub BUILD {
	my $self = shift;
	my $args = shift;
	my $matrix = Math::SparseMatrix->new($args->{row}, $args->{col});
	$self->matrix($matrix);	
	$self->matrix_rows($args->{row});
	$self->matrix_cols($args->{col});
}

sub train() {	
	my $self = shift;
	my @pattern = @_;	

	if ( ($#pattern + 1) != $self->matrix_rows) {
		die "Can't train a pattern of size " . ($#pattern + 1) . " on a hopfield network of size " , $self->matrix_rows;
	}
	
	my $m2 = &convert_array($self->matrix_rows, $self->matrix_cols, @pattern);

	my $m1 = &transpose($m2);

	my $m3 = &multiply($m1, $m2);

	my $identity = &identity($m3->{_rows});

	my $m4 = &subtract($m3, $identity);

	my $m5 = &add($self->matrix, $m4);
	
	$self->matrix($m5);	
}

sub evaluate() {
	my $self = shift;
	my @pattern = @_;

	my @output = ();

	my $input_matrix = &convert_array($self->matrix_rows, $self->matrix_cols, @pattern);

	for (my $col = 1; $col <= ($#pattern + 1); $col++) {
		
		my $column_matrix = &get_col($self, $col);
		
		my $transposed_column_matrix = &transpose($column_matrix);
		
		my $dot_product = &dot_product($input_matrix, $transposed_column_matrix);
		
		#say $dot_product;

		if ($dot_product > 0) {
			$output[$col - 1] = "true";
		} else {
			$output[$col - 1] = "false";
		}
	}
	return @output;
}

sub convert_array() {
	my $rows    = shift;
	my $cols 	= shift;
	my @pattern = @_;
	my $result  = Math::SparseMatrix->new(1, $cols);

	for (my $i = 0; $i < ($#pattern + 1); $i++) {
		if ($pattern[$i] =~ m/true/ig) {
			$result->set(1, ($i +1 ), 1);
		} else {
			$result->set(1, ($i + 1), -1);
		}
	}
	return $result;
}

sub transpose() {
	my $matrix  = shift;
	my $rows = $matrix->{_rows};
	my $cols = $matrix->{_cols};

	my $inverse = Math::SparseMatrix->new($cols, $rows);
		
	for (my $r = 1; $r <= $rows; $r++) {
		for (my $c = 1; $c <= $cols; $c++) {
			my $value = $matrix->get($r, $c);
			$inverse->set($c, $r, $value);
		}
	}
	return $inverse;
}

sub multiply() {
	my $matrix_a  = shift;
	my $matrix_b  = shift;

	my $a_rows = $matrix_a->{_rows};
	my $a_cols = $matrix_a->{_cols};

	my $b_rows = $matrix_b->{_rows};
	my $b_cols = $matrix_b->{_cols};

	my $result = Math::SparseMatrix->new($a_rows, $b_cols);

	if ($matrix_a->{_cols} != $matrix_b->{_rows}) {
		die "To use ordinary matrix multiplication the number of columns on the first matrix must mat the number of rows on the second";
	}

	for (my $result_row = 1; $result_row <= $a_rows; $result_row++) {
		for(my $result_col = 1; $result_col <= $b_cols; $result_col++) {
			my $value = 0;
			for (my $i = 1; $i <= $a_cols; $i++) {
				$value += ($matrix_a->get($result_row, $i)) * ($matrix_b->get($i, $result_col));
			}
			$result->set($result_row, $result_col, $value);
		}
	}
	return $result;
}

sub identity() {
	my $size = shift;

	if ($size < 1) {
		die "Identity matrix must be at least of size 1.";
	}
	
	my $result = Math::SparseMatrix->new ($size, $size);

	for (my $i = 1; $i <= $size; $i++) {
		$result->set($i, $i, 1);
	}
	return $result;
}

sub subtract() {
	my $matrix_a = shift;
	my $matrix_b = shift;

    my $a_rows = $matrix_a->{_rows};
    my $a_cols = $matrix_a->{_cols};

	my $b_rows = $matrix_b->{_rows};
	my $b_cols = $matrix_b->{_cols};

	if ($a_rows != $b_rows) {
		die "To subtract the matrixes they must have the same number of rows and columns.";
	}

	if ($a_cols != $b_cols) {
		die "To subtract the matrixes they must have the same number of rows and columns.  Matrix a has ";
	}

	my $result = Math::SparseMatrix->new($a_rows, $a_cols);

	for (my $result_row = 1; $result_row <= $a_rows; $result_row++) {
		for (my $result_col = 1; $result_col <= $a_cols; $result_col++) {
			my $value = ( $matrix_a->get($result_row, $result_col) ) - ( $matrix_b->get($result_row, $result_col));
			
			if ($value == 0) {
				$value += 2;
			}			
			$result->set($result_row, $result_col, $value);
		}
	}
	return $result;
}

sub add() {
	#weight matrix.
    my $matrix_a = shift;
	#identity matrix.
    my $matrix_b = shift;

	my $a_rows = $matrix_a->{_rows};
	my $a_cols = $matrix_a->{_cols};

	my $b_rows = $matrix_b->{_rows};
	my $b_cols = $matrix_b->{_cols};
	
	if ($a_rows != $b_rows) {
		die "To add the matrixes they must have the same number of rows and columns.";
	}

	if ($a_cols != $b_cols) {
		 die "To add the matrixes they must have the same number of rows and columns.";
	}

	my $result = Math::SparseMatrix->new($a_rows, $a_cols);

	for (my $result_row = 1; $result_row <= $a_rows; $result_row++) {
		for (my $result_col = 1; $result_col <= $a_cols; $result_col++) {
			my $value = $matrix_b->get($result_row, $result_col);			
			$result->set($result_row, $result_col, $matrix_a->get($result_row, $result_col) + $value  )
		}
	}
	return $result;
}

sub dot_product() {
	my $matrix_a = shift;
	my $matrix_b = shift;
	
	my $a_rows = $matrix_a->{_rows};
	my $a_cols = $matrix_a->{_cols};
	
	my $b_rows = $matrix_b->{_rows};
	my $b_cols = $matrix_b->{_cols};

	my @array_a = &packed_array($matrix_a);
	my @array_b = &packed_array($matrix_b);

	for (my $n = 0; $n <= $#array_b; $n++) {
		if ($array_b[$n] == 2) {
			$array_b[$n] = 0;
		}
	}
	
	if ($#array_a != $#array_b) {
		die "To take the dot product, both matrixes must be of the same length.";
	}

	my $result = 0;
	my $length = $#array_a + 1;

	for (my $i = 0; $i < $length; $i++) {
		$result += $array_a[$i] * $array_b[$i];
	}
	return $result;
}

sub packed_array() {
	my $matrix = shift;
	my @result = ();

	for (my $r = 1; $r <= $matrix->{_rows}; $r++) {
		for (my $c = 1; $c <= $matrix->{_cols}; $c++) {
			push(@result, $matrix->get($r, $c)); 
		}
	}
	return @result;
}

sub get_col() {
	my $self = shift;
	my $col  = shift;

	my $matrix = $self->matrix();
	
	my $matrix_rows = $self->matrix_rows();

	if ($col > $matrix_rows) {
		die "Can't get column";
	}

	my $new_matrix = Math::SparseMatrix->new($matrix_rows, 1);

	for (my $row = 1; $row <= $matrix_rows; $row++) {
		my $value = $matrix->get($row, $col);
		$new_matrix->set($row, 1, $value);
	}
	return $new_matrix;
}

sub print_matrix() {
    my $matrix  = shift;
    my $rs = $matrix->{_rows};
    my $cs = $matrix->{_cols};

	for (my $i = 1; $i <= $rs; $i++) {
		for (my $j = 1; $j <= $cs; $j++) {
			say "[$i,$j]" . $matrix->get($i, $j);
		}
	}
}

=head1 SYNOPSIS

This is a version of a Hopfield Network implemented in Perl. Hopfield networks are sometimes called associative networks since 
they associate a class pattern to each input pattern, they are tipically used for classification problems with binary pattern vectors.

=head1 SUBROUTINES/METHODS

=head2 New

In order to build new calssifiers, you have to pass to the constructor the number of rows and columns (neurons) for the matrix construction.

	my $hop = AI::NeuralNet::Hopfield->new(row => 4, col => 4);

=cut

=head2 Train

The training method configurates the network memory.

	my @input_1 = qw(true true false false);
	$hop->train(@input_1);

=cut

=head2 Evaluation

The evaluation method compares the new input with the information stored in the matrix memory.
The output is a new array with the boolean evaluation of each neuron.

	my @input_2 = qw(true true true false);
	my @result = $hop->evaluate(@input_2);

=cut


=head1 AUTHOR

Felipe da Veiga Leprevost, C<< <leprevost at cpan.org> >>

=head1 BUGS

Please report any bugs or feature requests to C<bug-ai-neuralnet-hopfield at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=AI-NeuralNet-Hopfield>.  I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.


=head1 SUPPORT

You can find documentation for this module with the perldoc command.