File Coverage

blib/lib/Games/Ratings/LogisticElo.pm

Criterion	Covered	Total	%
statement	35	35	100.0
branch	7	8	87.5
condition			n/a
subroutine	8	8	100.0
pod	3	3	100.0
total	53	54	98.1

package Games::Ratings::LogisticElo;

use 5.014000;
use strict;
use warnings;
use parent qw/Exporter Games::Ratings/;

our @EXPORT_OK = qw/multi_elo/;
our @EXPORT = qw//;
our $VERSION = '0.001';

use List::Util qw/sum/;

sub get_rating_change {
	my ($self) = @_;

	my $own_rating = $self->get_rating;
	my $K = $self->get_coefficient;

	my $expected = sum map {
		my $exp = ($_->{opponent_rating} - $own_rating) / 400;
		1 / (1 + 10 ** $exp)
	} $self->get_all_games;

	my $actual = sum map {
		Games::Ratings::_get_numerical_result($_->{result})
	} $self->get_all_games;

	$K * ($actual - $expected)
}

sub get_new_rating {
	my ($self) = @_;
	$self->get_rating + $self->get_rating_change
}

sub multi_elo {
	my @args = @_;
	my $K = ref $args[0] ? 15 : shift @args;

	my @newratings = map {
		my $player = __PACKAGE__->new;
		$player->set_rating($_->[0]);
		$player->set_coefficient($K);
		for my $opponent (@args) {
			$player->add_game({
				opponent_rating => $opponent->[0],
				result =>
				  $_->[1] > $opponent->[1] ? 'win' :
				  $_->[1] < $opponent->[1] ? 'loss' : 'draw'
			})
		}
		$player->get_new_rating
	} @args;

	wantarray ? @newratings : \@newratings
}

1;
__END__