I am building a plugin for a LAN party website that I wrote that would allow the use of a Round Robin tournament.
All is going well, but I have some questions about the most efficient way to rank over two criteria.
Basically, I would like the following ranking layout:
Rank Wins TotalScore
PersonE 1 5 50
PersonD 2 3.5 37
PersonA 2 3.5 37
PersonC 4 2.5 26
PersonB 5 2.5 24
PersonF 6 0 12
In SQL server, I would use:
SELECT
[Person],
RANK() OVER (ORDER BY Wins DESC, TotalScore DESC) [Rank],
[Wins],
[TotalScore]
Now, I only have List, Dictionary, and etc. to work with
Specifically:
Dictionary<TournamentTeam, double> wins = new Dictionary<TournamentTeam, double>();
Dictionary<TournamentTeam, double> score = new Dictionary<TournamentTeam, double>();
Is there a way to do this style of ranking with LINQ?
If not, is there an extensible way that would allow me later to take in to account Win-Loss-Draw instead of just wins if I choose to?
Edit:
My adaptation of TheSoftwareJedi's answer:
private class RRWinRecord : IComparable
{
public int Wins { get; set; }
public int Losses { get; set; }
public int Draws { get; set; }
public double OverallScore { get; set; }
public double WinRecord
{
get
{
return this.Wins * 1.0 + this.Draws * 0.5 + this.Losses * 0.0;
}
}
public int CompareTo(object obj) { ... }
public override bool Equals(object obj) { ... }
public override int GetHashCode() { ... }
public static bool operator ==(RRWinRecord lhs, RRWinRecord rhs) { ... }
public static bool operator !=(RRWinRecord lhs, RRWinRecord rhs) { ... }
public static bool operator >(RRWinRecord lhs, RRWinRecord rhs) { ... }
public static bool operator <(RRWinRecord lhs, RRWinRecord rhs) { ... }
public static bool operator >=(RRWinRecord lhs, RRWinRecord rhs) { ... }
public static bool operator <=(RRWinRecord lhs, RRWinRecord rhs) { ... }
}
...
int r = 1, lastRank = 1;
RRWinRecord lastRecord = null;
var ranks = from team in records.Keys
let teamRecord = records[team]
orderby teamRecord descending
select new RRRank() { Team = team, Rank = r++, Record = teamRecord };
foreach (var rank in ranks)
{
if (rank.Record != null && lastRecord == rank.Record)
{
rank.Rank = lastRank;
}
lastRecord = rank.Record;
lastRank = rank.Rank;
string scoreDescription = String.Format("{0}-{1}-{2}", rank.Record.Wins, rank.Record.Losses, rank.Record.Draws);
yield return new TournamentRanking(rank.Team, rank.Rank, scoreDescription);
}
yield break;
Ranking isn't too hard. Just mishmash OrderBy and Select implementation patterns together and you can have an easy to use Ranking extension method. Like this:
public static IEnumerable<U> Rank<T, TKey, U>
(
this IEnumerable<T> source,
Func<T, TKey> keySelector,
Func<T, int, U> selector
)
{
if (!source.Any())
{
yield break;
}
int itemCount = 0;
T[] ordered = source.OrderBy(keySelector).ToArray();
TKey previous = keySelector(ordered[0]);
int rank = 1;
foreach (T t in ordered)
{
itemCount += 1;
TKey current = keySelector(t);
if (!current.Equals(previous))
{
rank = itemCount;
}
yield return selector(t, rank);
previous = current;
}
}
Here's some test code
string[] myNames = new string[]
{ "Bob", "Mark", "John", "Jim", "Lisa", "Dave" };
//
var query = myNames.Rank(s => s.Length, (s, r) => new { s, r });
//
foreach (var x in query)
{
Console.WriteLine("{0} {1}", x.r, x.s);
}
Which yields these results:
1 Bob
1 Jim
3 Mark
3 John
3 Lisa
3 Dave
Assuming you have a List<Result>
structure where the Result
object has the following parameters...
Pesron - string
Rank - int
Wins - double
TotalScore - int
You could write a custom comparer, and then pass that to List.Sort(Comparison<Result> comparison)
Alternative, you could just make your Result
object implement IComparable<Result>
and stick this in your class.
#region IComparable Members
public int CompareTo(Result obj)
{
if (this.Rank.CompareTo(obj.Rank) != 0)
return this.Rank.CompareTo(obj.Rank);
if (this.Wins.CompareTo(obj.Wins) != 0)
return (this.Wins.CompareTo(obj.Wins);
return (this.TotalScore.CompareTo(obj.TotalScore) ;
}
#endregion
Then you can just call List<Result>.Sort()
;
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