Use *all* rated documents for ideal DCG computation. (#1242)

db/migrate/20250225162317_sync_communal_scorer_code.rb

@@ -0,0 +1,8 @@
+class SyncCommunalScorerCode < ActiveRecord::Migration[8.0]
+  def change    
+    Scorer.communal.each do |scorer|
+      file_name = scorer.name.downcase + '.js'    
+      scorer.update( code:               File.readlines("./db/scorers/#{file_name}",'\n').join('\n'))
+    end
+  end
+end

db/scorers/ap@10.js

@@ -17,7 +17,7 @@ eachDocWithRating(function(doc) {
     if (doc.rating > 0) {
         totalRel++;
     }
-}, bestDocs.length);
+});
 
 // AP is the sum of the precision points divided by the total
 // number of relevant documents

db/scorers/ndcg@10.js

@@ -1,34 +1,33 @@
-var k = 10 // @Rank
-var missing_rating = 0; // pessimistic assumption
-
-var ideal = topRatings(k) // could return less than k if less than k docs have ratings
-var scores = Array(k);
-for (var i = 0; i < k; i++) {
-  if (!ideal[i]) {
-    ideal[i] = missing_rating;
+const topK = 10 // @Rank
+const missing_rating = 0;
+const scores = Array(topK);
+const idealScores = []
+eachDocWithRating(function(doc) {
+    idealScores.push(doc.rating)
+})
+idealScores.sort(function(a,b) { return b - a; });
+for (var i = 0; i < topK; i++) {
+  if (!idealScores[i]) {
+    idealScores[i] = missing_rating;
   }
   if (hasDocRating(i)) {
     scores[i] = (docRating(i));
   } else {
     scores[i] = missing_rating;
   }
 }
-
 function DCG(vals, k) {
-  var dcg = 0;
-  for (var i = 0; i < k; i++) {
-    var d = Math.log2(i + 2);
-    var n = Math.pow(2, vals[i]) - 1;
-    dcg += d ? (n / d) : 0;
+  let dcg = 0;
+  for (var j = 0; j < k; j++) {
+    const den = Math.log2(j + 2);
+    const num = Math.pow(2, vals[j]) - 1;
+    dcg += den ? (num / den) : 0;
   }
   return dcg;
 }
-
 function nDCG(vals, ideal, k) {
-  var n = DCG(vals, k);
-  var d = DCG(ideal, k);
-  return d ? (n / d) : 0;
+  const num = DCG(vals, k);
+  const den = DCG(ideal, ideal.length);
+  return den ? (num / den) : 0;
 }
-
-setScore(nDCG(scores, ideal, k));
-
+setScore(nDCG(scores, idealScores, topK));