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lib/AI/Fuzzy/Set.pm  view on Meta::CPAN

package AI::Fuzzy::Set;

## Fuzzy Set ####

sub new { 

    my $class = shift;
    my $self = {} ;

    # accepts a hash of member weights..
    # ( $members{$member}=$weight )

    %{$self->{members}} = @_;
    bless $self, $class;
}

sub membership {
    # naturally, it returns a fuzzy value - the degree
    # to wich $item is a member of the set! :)

    my $self = shift;
    my $item = shift;

    if (defined(${$self->{members}}{$item})) {
	return ${$self->{members}}{$item};
    } else {
	return 0;
    }
}

sub members {
    # returns list of members, sorted from least membership to greatest
    my $self = shift;

    my %l = %{$self->{members}};
    return sort { $l{$a} <=> $l{$b} } keys %l;
}

sub equal {
    # returns true if the argument set is equal to this one
    my $self = shift;
    my $otherset = shift;

    my (%us, %them);
    %us = %{$self->{members}} if (exists $self->{members});
    %them = %{$otherset->{members}} if (exists $otherset->{members});

    # for all keys in us and them
    foreach my $key (keys (%us), keys (%them)) {
	# not equal if either set is missing a key
	return 0 unless (exists ($us{$key}) && exists ($them{$key}) );

	# not equal if the membership of the keys isn't equal
	return 0 unless (float_equal($us{$key},$them{$key}, 10));
    }

    # otherwise they are equal
    return 1;
}

sub union {
    # returns a set that is the union of us and the argument set
    my $self = shift;
    my $otherset = shift;

    my (%us, %them, %new);
    %us = %{$self->{members}} if (exists $self->{members});
    %them = %{$otherset->{members}} if (exists $otherset->{members});

    # for all keys in us and them
    foreach my $key (keys (%us), keys (%them)) {
	if (not exists $us{$key} and exists $them{$key}) {
	    $new{$key} = $them{$key};
	    next;