public function calculateNewRatings(GameInfo $gameInfo, array $teams, array $teamRanks)
{
Guard::argumentNotNull($gameInfo, "gameInfo");
$this->validateTeamCountAndPlayersCountPerTeam($teams);
RankSorter::sort($teams, $teamRanks);
$factorGraph = new TrueSkillFactorGraph($gameInfo, $teams, $teamRanks);
$factorGraph->buildGraph();
$factorGraph->runSchedule();
$probabilityOfOutcome = $factorGraph->getProbabilityOfRanking();
return $factorGraph->getUpdatedRatings();
}
/**
* {@inheritdoc }
*/
public function calculateMatchQuality(GameInfo $gameInfo, array $teams)
{
Guard::argumentNotNull($gameInfo, "gameInfo");
$this->validateTeamCountAndPlayersCountPerTeam($teams);
$team1 = $teams[0];
$team2 = $teams[1];
$team1Ratings = $team1->getAllRatings();
$team2Ratings = $team2->getAllRatings();
$player1Rating = $team1Ratings[0];
$player2Rating = $team2Ratings[0];
// We just use equation 4.1 found on page 8 of the TrueSkill 2006 paper:
$betaSquared = square($gameInfo->getBeta());
$player1SigmaSquared = square($player1Rating->getStandardDeviation());
$player2SigmaSquared = square($player2Rating->getStandardDeviation());
// This is the square root part of the equation:
$sqrtPart = sqrt(2 * $betaSquared / (2 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared));
// This is the exponent part of the equation:
$expPart = exp(-1 * square($player1Rating->getMean() - $player2Rating->getMean()) / (2 * (2 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared)));
return $sqrtPart * $expPart;
}
/**
* {@inheritdoc }
*/
public function calculateMatchQuality(GameInfo &$gameInfo, array &$teams)
{
Guard::argumentNotNull($gameInfo, "gameInfo");
$this->validateTeamCountAndPlayersCountPerTeam($teams);
// We've verified that there's just two teams
$team1Ratings = $teams[0]->getAllRatings();
$team1Count = count($team1Ratings);
$team2Ratings = $teams[1]->getAllRatings();
$team2Count = count($team2Ratings);
$totalPlayers = $team1Count + $team2Count;
$betaSquared = square($gameInfo->getBeta());
$meanGetter = function ($currentRating) {
return $currentRating->getMean();
};
$varianceGetter = function ($currentRating) {
return square($currentRating->getStandardDeviation());
};
$team1MeanSum = sum($team1Ratings, $meanGetter);
$team1StdDevSquared = sum($team1Ratings, $varianceGetter);
$team2MeanSum = sum($team2Ratings, $meanGetter);
$team2SigmaSquared = sum($team2Ratings, $varianceGetter);
// This comes from equation 4.1 in the TrueSkill paper on page 8
// The equation was broken up into the part under the square root sign and
// the exponential part to make the code easier to read.
$sqrtPart = sqrt($totalPlayers * $betaSquared / ($totalPlayers * $betaSquared + $team1StdDevSquared + $team2SigmaSquared));
$expPart = exp(-1 * square($team1MeanSum - $team2MeanSum) / (2 * ($totalPlayers * $betaSquared + $team1StdDevSquared + $team2SigmaSquared)));
return $expPart * $sqrtPart;
}
