fix broken instant glicko

niklasf · Nov 2, 2024 · aaf33ed · aaf33ed
1 parent 8444597
commit aaf33ed
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Showing 3 changed files with 38 additions and 52 deletions.
diff --git a/research/src/bin/replay_encounters.rs b/research/src/bin/replay_encounters.rs
@@ -370,19 +370,18 @@ fn write_report<W: Write>(
 
     writeln!(
         writer,
-        "min_deviation,max_deviation,default_volatility,tau,first_advantage,preview_opponent_deviation,rating_periods_per_day,avg_deviance"
+        "min_deviation,max_deviation,default_volatility,tau,first_advantage,rating_periods_per_day,avg_deviance"
     )?;
 
     for experiment in experiments.iter() {
         writeln!(
             writer,
-            "{},{},{},{},{},{},{},{}",
+            "{},{},{},{},{},{},{}",
             f64::from(experiment.rating_system.min_deviation()),
             f64::from(experiment.rating_system.max_deviation()),
             f64::from(experiment.rating_system.default_volatility()),
             experiment.rating_system.tau(),
             f64::from(experiment.rating_system.first_advantage()),
-            experiment.rating_system.preview_opponent_deviation(),
             experiment.rating_periods_per_day,
             experiment.avg_deviance()
         )?;
@@ -461,8 +460,6 @@ struct Opt {
     tau: Vec<f64>,
     #[clap(long, value_delimiter = ',', num_args = 1.., default_value = "0")]
     first_advantage: Vec<f64>,
-    #[clap(long, value_delimiter = ',', num_args = 1.., default_value = "1")]
-    preview_opponent_deviation: Vec<u8>,
     #[clap(long, value_delimiter = ',', num_args = 1.., default_value = "0.21436")]
     rating_periods_per_day: Vec<f64>,
 }
@@ -479,24 +476,21 @@ fn main() -> Result<(), Box<dyn StdError>> {
             for &default_volatility in &opt.default_volatility {
                 for &tau in &opt.tau {
                     for &first_advantage in &opt.first_advantage {
-                        for &preview_opponent_deviation in &opt.preview_opponent_deviation {
-                            for &rating_periods_per_day in &opt.rating_periods_per_day {
-                                experiments.push(Experiment {
-                                    rating_system: RatingSystem::builder()
-                                        .rating_regulator_factor(1.0)
-                                        .min_rating(RatingScalar(-f64::INFINITY))
-                                        .max_rating(RatingScalar(f64::INFINITY))
-                                        .min_deviation(RatingDifference(min_deviation))
-                                        .max_deviation(RatingDifference(max_deviation))
-                                        .default_volatility(Volatility(default_volatility))
-                                        .tau(tau)
-                                        .first_advantage(RatingDifference(first_advantage))
-                                        .preview_opponent_deviation(preview_opponent_deviation != 0)
-                                        .build(),
-                                    rating_periods_per_day,
-                                    ..Default::default()
-                                });
-                            }
+                        for &rating_periods_per_day in &opt.rating_periods_per_day {
+                            experiments.push(Experiment {
+                                rating_system: RatingSystem::builder()
+                                    .rating_regulator_factor(1.0)
+                                    .min_rating(RatingScalar(-f64::INFINITY))
+                                    .max_rating(RatingScalar(f64::INFINITY))
+                                    .min_deviation(RatingDifference(min_deviation))
+                                    .max_deviation(RatingDifference(max_deviation))
+                                    .default_volatility(Volatility(default_volatility))
+                                    .tau(tau)
+                                    .first_advantage(RatingDifference(first_advantage))
+                                    .build(),
+                                rating_periods_per_day,
+                                ..Default::default()
+                            });
                         }
                     }
                 }

diff --git a/src/instant.rs b/src/instant.rs
@@ -85,6 +85,20 @@ impl From<f64> for Periods {
     }
 }
 
+impl Periods {
+    #[must_use]
+    #[inline]
+    pub fn max(self, other: Periods) -> Periods {
+        Periods(f64::max(self.0, other.0))
+    }
+
+    #[must_use]
+    #[inline]
+    pub fn min(self, other: Periods) -> Periods {
+        Periods(f64::min(self.0, other.0))
+    }
+}
+
 impl Add for Periods {
     type Output = Periods;
 

diff --git a/src/rating_system.rs b/src/rating_system.rs
@@ -34,8 +34,6 @@ pub struct RatingSystemBuilder {
 
     first_advantage: RatingDifference,
 
-    preview_opponent_deviation: bool,
-
     tau: f64,
 
     convergence_tolerance: f64,
@@ -115,13 +113,6 @@ impl RatingSystemBuilder {
         self
     }
 
-    /// Set whether to apply time decay to the second rating deviation when
-    /// updating the first rating and vice versa. The default is `false`.
-    pub fn preview_opponent_deviation(&mut self, preview_opponent_deviation: bool) -> &mut Self {
-        self.preview_opponent_deviation = preview_opponent_deviation;
-        self
-    }
-
     /// Set the tolerance for the convergence in step 5.4 of the Glicko-2
     /// algorithm. The default is `1e-6`.
     pub fn convergence_tolerance(&mut self, convergence_tolerance: f64) -> &mut Self {
@@ -173,8 +164,6 @@ impl RatingSystemBuilder {
 
             first_advantage: self.first_advantage,
 
-            preview_opponent_deviation: self.preview_opponent_deviation,
-
             tau: self.tau,
 
             convergence_tolerance: self.convergence_tolerance,
@@ -207,8 +196,6 @@ pub struct RatingSystem {
 
     first_advantage: RatingDifference,
 
-    preview_opponent_deviation: bool,
-
     tau: f64,
 
     convergence_tolerance: f64,
@@ -245,8 +232,6 @@ impl RatingSystem {
 
             first_advantage: RatingDifference(0.0),
 
-            preview_opponent_deviation: false,
-
             tau: 0.75,
 
             convergence_tolerance: 1e-6,
@@ -297,10 +282,6 @@ impl RatingSystem {
         self.first_advantage
     }
 
-    pub fn preview_opponent_deviation(&self) -> bool {
-        self.preview_opponent_deviation
-    }
-
     pub fn tau(&self) -> f64 {
         self.tau
     }
@@ -401,16 +382,13 @@ impl RatingSystem {
         advantage: RatingDifference,
     ) -> Result<Rating, ConvergenceError> {
         // Step 2
-        let phi = us.deviation.to_internal();
+        let phi = self.preview_deviation(us, now - Periods(1.0)).to_internal(); // Notable change!
 
         // Step 3
-        let their_g = g(RatingDifference::to_internal(
-            if self.preview_opponent_deviation {
-                self.preview_deviation(them, now)
-            } else {
-                them.deviation
-            },
-        ));
+        let their_g = g(self
+            .preview_deviation(them, now - Periods(1.0)) // Notable change!
+            .to_internal());
+
         let expected =
             expectation_value((us.rating - them.rating + advantage).to_internal(), their_g);
         let v = 1.0 / (their_g.powi(2) * expected.value() * expected.opposite().value());
@@ -471,7 +449,7 @@ impl RatingSystem {
         let phi_star = new_deviation(
             us.deviation.to_internal(),
             sigma_prime,
-            now.elapsed_since(us.at),
+            Periods::min(now.elapsed_since(us.at), Periods(1.0)), // Notable change!
         );
 
         // Step 7
@@ -527,7 +505,7 @@ fn new_deviation(
     elapsed: Periods,
 ) -> InternalRatingDifference {
     InternalRatingDifference(f64::sqrt(
-        deviation.sq() + f64::max(elapsed.0, 0.0) * volatility.sq(),
+        deviation.sq() + Periods::max(elapsed, Periods(0.0)).0 * volatility.sq(),
     ))
 }