File Coverage

blib/lib/Math/EWMA.pm

Criterion	Covered	Total	%
statement	19	19	100.0
branch	6	6	100.0
condition			n/a
subroutine	4	4	100.0
pod	1	1	100.0
total	30	30	100.0

package Math::EWMA;
use Moo;
use namespace::autoclean;
use Scalar::Util qw(looks_like_number);

our $VERSION = '0.02';
$VERSION = eval $VERSION;


has alpha => (
	is =>'ro',
	isa => sub { die "$_[0] is not a number!" unless looks_like_number $_[0]},
	required => '1',
);

has last_avg => (
	is =>'ro',
	isa => sub { die "$_[0] is not a number!" unless looks_like_number $_[0]},
	writer => '_set_last_avg',
);

has precision => (
	is => 'rw',
	isa => sub { die "$_[0] is not a number!" unless looks_like_number $_[0]},
	default => 2,
);


sub ewma
{
	my ($self, $current) = @_;
	my $last = $self->last_avg();
	my $alpha = $self->alpha();
	my $prec = $self->precision();

	return sprintf("%.${prec}f",$last) unless defined $current;
	die "ewma() works on numbers only!" unless looks_like_number $current;

	$last = $current if not defined $last;
	my $ewma = (1 - $alpha) * $last + $alpha * $current;
	$self->_set_last_avg($ewma);
	return sprintf("%.${prec}f",$ewma);
}


__PACKAGE__->meta->make_immutable;
1;

__END__