Skip to content

Fix PlackettLuce handling of ties #1

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
myssto merged 4 commits into from
Dec 20, 2025
Merged

Fix PlackettLuce handling of ties #1

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
5f747c6
Update test data to produce failing tests
smoogipoo Dec 15, 2025
2c39577
Fix PlackettLuce handling of ties
smoogipoo Dec 15, 2025
ad9cc65
Add another failing test
smoogipoo Dec 15, 2025
d551f2f
Fix exception when all scores are tied
smoogipoo Dec 15, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 9 additions & 9 deletions OpenSkillSharp.Tests/Models/Data/plackettluce.json
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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
}
],
Expand Down Expand Up @@ -160,7 +160,7 @@
"ties": {
"team_1": [
{
"mu": 23.241111866333558,
"mu": 21.63766806988004,
"sigma": 8.310709773172306
}
],
Expand All @@ -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
}
]
Expand Down Expand Up @@ -261,4 +261,4 @@
}
]
}
}
}
12 changes: 12 additions & 0 deletions OpenSkillSharp.Tests/Models/PlackettLuceTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
}
2 changes: 1 addition & 1 deletion OpenSkillSharp/Models/PlackettLuce.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ protected override IEnumerable<ITeam> Compute(
return (
sumOmega: acc.sumOmega + (
iTeamIndex == qTeamIndex
? 1 - (iMuOverCeOverSumQ / rankOccurrences[qTeamIndex])
? (1 - iMuOverCeOverSumQ) / rankOccurrences[qTeamIndex]
: -1 * iMuOverCeOverSumQ / rankOccurrences[qTeamIndex]
),
sumDelta: acc.sumDelta +
Expand Down
1 change: 1 addition & 0 deletions OpenSkillSharp/OpenSkillModelBase.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -289,6 +289,7 @@ protected IEnumerable<double> CalculateMarginAdjustedMu(
double sign = qTeamScore > iTeamScore ? 1D : -1D;
return (qTeam.Mu - iTeam.Mu) * (marginFactor - 1) * sign;
})
.DefaultIfEmpty(0)
.Average();

return qTeam.Mu + muAdjustment;
Expand Down