Ensure good matchups per gender across teams

Previously, two teams would be considered "even" if one had
3 experienced males and 3 experienced females. Since males
generally mark males and females mark females, this would create
a lot of poor matchups on the field.

With this change, team allocation prefers combinations where
not only is the overall skill the same between teams, but also the
amount of skill per gender.

KingsAndQueensHat/KingsAndQueensHat.csproj

@@ -60,6 +60,7 @@
     <Compile Include="Model\PlayerEventArgs.cs" />
     <Compile Include="Model\TournamentSettings.cs" />
     <Compile Include="Persistence\StorageLocator.cs" />
+    <Compile Include="TeamGeneration\UnevenGenderSkillPenalty.cs" />
     <Compile Include="ViewModel\GenderRanking.cs" />
     <Compile Include="Persistence\InvalidRoundException.cs" />
     <Compile Include="Properties\Annotations.cs" />

KingsAndQueensHat/Model/Team.cs

@@ -85,6 +85,15 @@ public int TotalSkill
             get { return Players.Sum(p => p.SkillValue); }
         }
 
+        [XmlIgnore]
+        public Dictionary<Gender, int> GenderSkills
+        {
+            get 
+            { 
+                return Players.GroupBy(p => p.Gender).Select(g => new {g.Key, Skill = g.Sum(p => p.SkillValue)}).ToDictionary(x => x.Key, x => x.Skill); 
+            }
+        }
+
         [XmlIgnore]
         public int PlayerCount
         {

KingsAndQueensHat/Model/Tournament.cs

@@ -154,7 +154,8 @@ public async Task CreateNewRound(int teamCount, CancellationToken cancel)
             var penalty1 = new UnevenSkillPenalty();
             var penalty3 = new TooManyWinnersPenalty(PlayerProvider);
             var penalty4 = new RangeOfSkillsPenalty();
-            var penalties = new IPenalty[] { penalty1, _playerPairings, penalty3, penalty4 };
+            var penalty5 = new UnevenGenderSkillPenalty();
+            var penalties = new IPenalty[] { penalty1, _playerPairings, penalty3, penalty4, penalty5 };
 
             var teams = await teamCreator.CreateApproximatelyOptimalTeams(penalties, PlayerProvider, numTeamGens, teamCount, cancel);
 

KingsAndQueensHat/TeamGeneration/UnevenGenderSkillPenalty.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using KingsAndQueensHat.Model;
+
+namespace KingsAndQueensHat.TeamGeneration
+{
+    /// <summary>
+    /// Penalise team allocations that leave some teams with a particular dominant gender
+    /// , while others do not
+    /// </summary>
+    public class UnevenGenderSkillPenalty : IPenalty
+    {
+        public double ScorePenalty(List<Team> teams)
+        {
+            var scores = teams.Select(team => team.GenderSkills).ToList();
+            int result = 0;
+            foreach (var gender in new[] { Gender.Male, Gender.Female })
+            {
+                var total = scores.Sum(s => s[gender]);
+                var teamCount = teams.Count;
+                var expectedTeamGenderSkill = total / teamCount;
+
+                // Sum the deviations from the expected team skill
+                result += scores.Sum(s => Math.Abs(s[gender] - expectedTeamGenderSkill));
+            }
+            return result;
+        }
+
+        public double Weighting { get { return 1.0; } }
+    }
+}