public void TestMatchAgainstWikipediaValues()
{
// Suppose Player A has a rating of 1613, and plays in a five-round tournament.
// He or she loses to a player rated 1609, draws with a player rated 1477,
// defeats a player rated 1388, defeats a player rated 1586, and loses to a
// player rated 1720. The player's actual score is
// (0 + 0.5 + 1 + 1 + 0) = 2.5. The expected score, calculated according to
// the formula above, was (0.506 + 0.686 + 0.785 + 0.539 + 0.351) = 2.867.
// Therefore, the player's new rating is (1613 + 32×(2.5 − 2.867)) = 1601,
// assuming that a K-factor of 32 is used.
var elo = new EloSystem(k: 32);
var tournament = new RatingPeriod(elo);
var playerA = new Player(1613);
var teamA = new Team(playerA);
var games = new[]
{
teamA.LosesTo(new Team(new Player(1609))),
teamA.Draws(new Team(new Player(1477))),
teamA.Defeats(new Team(new Player(1388))),
teamA.Defeats(new Team(new Player(1586))),
teamA.LosesTo(new Team(new Player(1720)))
};
foreach (var game in games)
{
tournament.AddGame(game);
}
var teamsToNewRank = tournament.UpdateRankings();
var teamANewRank = teamsToNewRank.First(tup => tup.Item1 == playerA).Item2;
Assert.AreEqual(1601, teamANewRank.Value, 1.0);
}
public void TestPlayerAGainsWhatPlayerBLoses()
{
var elo = new EloSystem(k: 32);
var rp = new RatingPeriod(elo);
var playerAStart = 1500;
var playerA = new Player(playerAStart);
var teamA = new Team(playerA);
var playerBStart = 1700;
var playerB = new Player(playerBStart);
var teamB = new Team(playerB);
rp.AddGame(teamA.Defeats(teamB));
var newRankings = rp.UpdateRankings();
var diffA = Math.Abs(newRankings.Where(p => p.Item1 == playerA).First().Item2.Value - playerAStart);
var diffB = Math.Abs(newRankings.Where(p => p.Item1 == playerB).First().Item2.Value - playerBStart);
Assert.AreEqual(diffA, diffB, .1);
}
public RatingPeriod(EloSystem eloSystem)
{
Contract.Requires(eloSystem != null);
this._elo = eloSystem;
}