public double calculateRatingChangeForPlayer(RatingsPlayer player, IEnumerable <RatingsSet> sets, IEnumerable <RatingsPlayer> players)
{
var playerSets = (from s in sets
where s.WinnerID == player.PlayerId || s.LoserID == player.PlayerId
select s).Distinct();
HashSet <int> playerOpponentIDs = new HashSet <int>();
foreach (RatingsSet set in playerSets)
{
playerOpponentIDs.Add(set.WinnerID);
playerOpponentIDs.Add(set.LoserID);
}
playerOpponentIDs.Remove(player.PlayerId);
var playerOpponents = from p in players
where playerOpponentIDs.Contains(p.PlayerId)
select p;
double expectedScore = getExpectedScoreForTournament(player, playerOpponents, playerSets);
double actualScore = getActualScore(playerSets, player.PlayerId);
var ratingChange = getRatingChange(getKFactor(player.ELO), actualScore, expectedScore);
playerSets = null;
GC.Collect();
return(ratingChange);
}
private double getExpectedScoreForTournament(RatingsPlayer player, IEnumerable <RatingsPlayer> playerOpponents, IEnumerable <RatingsSet> playerSets)
{
double expectedScore = 0;
foreach (RatingsSet set in playerSets)
{
var opponent = set.WinnerID == player.PlayerId ? playerOpponents.First(p => p.PlayerId == set.LoserID) :
playerOpponents.First(p => p.PlayerId == set.WinnerID);
expectedScore += getExpectedScore(player.ELO, opponent.ELO);
}
return(expectedScore);
}