Merge remote-tracking branch 'origin/master' into predict-rank

# Conflicts:
#	OpenSkillSharp/Models/PlackettLuce.cs
#	OpenSkillSharp/OpenSkillModelBase.cs

Author: myssto

OpenSkillSharp.Tests/Models/Data/plackettluce.json

@@ -86,21 +86,21 @@
     ],
     "team_2": [
       {
-        "mu": 23.083700519022745,
+        "mu": 20.599656070925114,
         "sigma": 8.222674397835641
       },
       {
-        "mu": 21.717476072569045,
+        "mu": 20.47545384852023,
         "sigma": 8.277466291367071
       }
     ],
     "team_3": [
       {
-        "mu": 21.717476072569045,
+        "mu": 20.47545384852023,
         "sigma": 8.277466291367071
       },
       {
-        "mu": 23.083700519022745,
+        "mu": 20.599656070925114,
         "sigma": 8.222674397835641
       }
     ],
@@ -160,7 +160,7 @@
   "ties": {
     "team_1": [
       {
-        "mu": 23.241111866333558,
+        "mu": 21.63766806988004,
         "sigma": 8.310709773172306
       }
     ],
@@ -176,15 +176,15 @@
     ],
     "team_3": [
       {
-        "mu": 21.479966996534408,
+        "mu": 19.87652320008089,
         "sigma": 8.237522411103104
       },
       {
-        "mu": 21.479966996534408,
+        "mu": 19.87652320008089,
         "sigma": 8.237522411103104
       },
       {
-        "mu": 21.479966996534408,
+        "mu": 19.87652320008089,
         "sigma": 8.237522411103104
       }
     ]
@@ -261,4 +261,4 @@
       }
     ]
   }
-}
+}

OpenSkillSharp.Tests/Models/PlackettLuceTests.cs

@@ -149,4 +149,16 @@ public void Rate_Balance()
         // Assert
         Assertions.RatingResultsEqual(expectedRatings, results);
     }
+
+    [Fact]
+    public void Rate_AllScoresTied()
+    {
+        PlackettLuce model = new PlackettLuce { Mu = 30, Sigma = 30.0 / 3 };
+
+        ITeam[] teams = [new Team { Players = [model.Rating()] }, new Team { Players = [model.Rating()] }];
+        ITeam[] result = model.Rate(teams, scores: [0, 0]).ToArray();
+
+        Assert.Equal(30, result[0].Players.Single().Mu);
+        Assert.Equal(30, result[1].Players.Single().Mu);
+    }
 }

OpenSkillSharp/Models/PlackettLuce.cs

@@ -44,7 +44,7 @@ protected override IEnumerable<ITeam> Compute(
                                     sumOmega: acc.sumOmega +
                                               (
                                                   iTeamIndex == qTeamIndex
-                                                      ? 1 - (iMuOverCeOverSumQ / rankOccurrences[qTeamIndex])
+                                                      ? (1 - iMuOverCeOverSumQ) / rankOccurrences[qTeamIndex]
                                                       : -1 * iMuOverCeOverSumQ / rankOccurrences[qTeamIndex]
                                               ),
                                     sumDelta: acc.sumDelta +

OpenSkillSharp/OpenSkillModelBase.cs

@@ -352,6 +352,7 @@ protected IEnumerable<double> CalculateMarginAdjustedMu(
                             return (qTeam.Mu - iTeam.Mu) * (marginFactor - 1) * sign;
                         }
                     )
+                    .DefaultIfEmpty(0)
                     .Average();
 
                 return qTeam.Mu + muAdjustment;