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lib/AI/Categorizer/FeatureVector.pm  view on Meta::CPAN

package AI::Categorizer::FeatureVector;

sub new {
  my ($package, %args) = @_;
  $args{features} ||= {};
  return bless {features => $args{features}}, $package;
}

sub names {
  my $self = shift;
  return keys %{$self->{features}};
}

sub set {
  my $self = shift;
  $self->{features} = (ref $_[0] ? $_[0] : {@_});
}

sub as_hash {
  my $self = shift;
  return $self->{features};
}

sub euclidean_length {
  my $self = shift;
  my $f = $self->{features};

  my $total = 0;
  foreach (values %$f) {
    $total += $_**2;
  }
  return sqrt($total);
}

sub normalize {
  my $self = shift;

  my $length = $self->euclidean_length;
  return $length ? $self->scale(1/$length) : $self;
}

sub scale {
  my ($self, $scalar) = @_;
  $_ *= $scalar foreach values %{$self->{features}};
  return $self;
}

sub as_boolean_hash {
  my $self = shift;
  return { map {($_ => 1)} keys %{$self->{features}} };
}

sub length {
  my $self = shift;
  return scalar keys %{$self->{features}};
}

sub clone {
  my $self = shift;
  return ref($self)->new( features => { %{$self->{features}} } );
}

sub intersection {
  my ($self, $other) = @_;
  $other = $other->as_hash if UNIVERSAL::isa($other, __PACKAGE__);