From 7e2576085f779ffa85d17638dc67a91aac96077b Mon Sep 17 00:00:00 2001
From: Anders Olsson <anders.olsson@digitalistgroup.com>
Date: Thu, 26 Oct 2023 11:11:54 +0200
Subject: [PATCH] Make quality a free standing function instead

---
 src/history.rs | 62 --------------------------------------------------
 src/lib.rs     | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 62 deletions(-)

diff --git a/src/history.rs b/src/history.rs
index 0d26b8c..4a09dc4 100644
--- a/src/history.rs
+++ b/src/history.rs
@@ -4,7 +4,6 @@ use crate::{
     agent::{self, Agent},
     batch::{self, Batch},
     gaussian::Gaussian,
-    matrix::Matrix,
     player::Player,
     sort_time, tuple_gt, tuple_max, Index, BETA, GAMMA, MU, P_DRAW, SIGMA,
 };
@@ -418,67 +417,6 @@ impl History {
 
         self.size += n;
     }
-
-    pub fn quality(&self, rating_groups: &[&[Gaussian]]) -> f64 {
-        let flatten_ratings = rating_groups
-            .iter()
-            .flat_map(|group| group.iter())
-            .collect::<Vec<_>>();
-
-        let flatten_weights = vec![1.0; flatten_ratings.len()].into_boxed_slice();
-
-        let length = flatten_ratings.len();
-
-        let mut mean_matrix = Matrix::new(length, 1);
-
-        for (i, rating) in flatten_ratings.iter().enumerate() {
-            mean_matrix[(i, 0)] = rating.mu;
-        }
-
-        let mut variance_matrix = Matrix::new(length, length);
-
-        for (i, rating) in flatten_ratings.iter().enumerate() {
-            variance_matrix[(i, i)] = rating.sigma.powi(2);
-        }
-
-        let mut rotated_a_matrix = Matrix::new(rating_groups.len() - 1, length);
-
-        let mut t = 0;
-        let mut x = 0;
-
-        for (row, group) in rating_groups.windows(2).enumerate() {
-            let current = group[0];
-            let next = group[1];
-
-            for n in t..t + current.len() {
-                rotated_a_matrix[(row, n)] = flatten_weights[n];
-
-                x += 1;
-            }
-
-            t += current.len();
-
-            for n in x..x + next.len() {
-                rotated_a_matrix[(row, n)] = -flatten_weights[n];
-            }
-
-            x += next.len();
-        }
-
-        let a_matrix = rotated_a_matrix.transpose();
-
-        let ata = self.beta.powi(2) * &rotated_a_matrix * &a_matrix;
-        let atsa = &rotated_a_matrix * &variance_matrix * &a_matrix;
-
-        let start = mean_matrix.transpose() * &a_matrix;
-        let middle = &ata + &atsa;
-        let end = &rotated_a_matrix * &mean_matrix;
-
-        let e_arg = (-0.5 * &start * &middle.inverse() * &end).determinant();
-        let s_arg = ata.determinant() / middle.determinant();
-
-        e_arg.exp() * s_arg.sqrt()
-    }
 }
 
 #[cfg(test)]
diff --git a/src/lib.rs b/src/lib.rs
index 76fb17b..2a74c02 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,6 +18,7 @@ pub mod player;
 pub use game::Game;
 pub use gaussian::Gaussian;
 pub use history::History;
+use matrix::Matrix;
 use message::DiffMessage;
 pub use player::Player;
 
@@ -255,6 +256,67 @@ pub(crate) fn evidence(d: &[DiffMessage], margin: &[f64], tie: &[bool], e: usize
     }
 }
 
+pub fn quality(rating_groups: &[&[Gaussian]], beta: f64) -> f64 {
+    let flatten_ratings = rating_groups
+        .iter()
+        .flat_map(|group| group.iter())
+        .collect::<Vec<_>>();
+
+    let flatten_weights = vec![1.0; flatten_ratings.len()].into_boxed_slice();
+
+    let length = flatten_ratings.len();
+
+    let mut mean_matrix = Matrix::new(length, 1);
+
+    for (i, rating) in flatten_ratings.iter().enumerate() {
+        mean_matrix[(i, 0)] = rating.mu;
+    }
+
+    let mut variance_matrix = Matrix::new(length, length);
+
+    for (i, rating) in flatten_ratings.iter().enumerate() {
+        variance_matrix[(i, i)] = rating.sigma.powi(2);
+    }
+
+    let mut rotated_a_matrix = Matrix::new(rating_groups.len() - 1, length);
+
+    let mut t = 0;
+    let mut x = 0;
+
+    for (row, group) in rating_groups.windows(2).enumerate() {
+        let current = group[0];
+        let next = group[1];
+
+        for n in t..t + current.len() {
+            rotated_a_matrix[(row, n)] = flatten_weights[n];
+
+            x += 1;
+        }
+
+        t += current.len();
+
+        for n in x..x + next.len() {
+            rotated_a_matrix[(row, n)] = -flatten_weights[n];
+        }
+
+        x += next.len();
+    }
+
+    let a_matrix = rotated_a_matrix.transpose();
+
+    let ata = beta.powi(2) * &rotated_a_matrix * &a_matrix;
+    let atsa = &rotated_a_matrix * &variance_matrix * &a_matrix;
+
+    let start = mean_matrix.transpose() * &a_matrix;
+    let middle = &ata + &atsa;
+    let end = &rotated_a_matrix * &mean_matrix;
+
+    let e_arg = (-0.5 * &start * &middle.inverse() * &end).determinant();
+    let s_arg = ata.determinant() / middle.determinant();
+
+    e_arg.exp() * s_arg.sqrt()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;