Fixed scale projection

kataklinger · Mar 14, 2024 · c6628a8 · c6628a8
1 parent dd630e0
commit c6628a8
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Showing 2 changed files with 14 additions and 10 deletions.
diff --git a/src/inc/projection.hpp b/src/inc/projection.hpp
@@ -38,6 +38,9 @@ class none {
 // x = rank / (1. - density) (nsga)
 template<typename RankTag>
 class scale {
+private:
+  inline static constexpr double epsilon = 0.00001;
+
 public:
   template<projectable_context<RankTag, double> Context, typename Preserved>
   void operator()(
@@ -51,7 +54,7 @@ class scale {
 
     for (auto&& individual : context.population().individuals()) {
       auto front = get_tag<frontier_level_t>(individual).get() - 1;
-      double density{get_tag<crowd_density_t>(individual)};
+      auto density = 1. - get_tag<crowd_density_t>(individual).get();
 
       if (multipliers[front] > density) {
         multipliers[front] = density;
@@ -60,13 +63,14 @@ class scale {
 
     for (auto correction = 1.0;
          auto&& multiplier : multipliers | std::views::reverse) {
-      correction *= std::exchange(multiplier, multiplier / correction);
+      correction /= multiplier > epsilon ? multiplier : epsilon;
+      multiplier = correction;
     }
 
     for (auto&& individual : context.population().individuals()) {
       auto front = get_tag<frontier_level_t>(individual).get() - 1;
-      auto scaled = multipliers[front] * get_tag<RankTag>(individual).get() *
-                    get_tag<crowd_density_t>(individual).get();
+      auto scaled = multipliers[front] *
+                    (1. - get_tag<crowd_density_t>(individual).get());
 
       individual.eval().set_scaled(scaled_fitness_t{scaled});
     }

diff --git a/tests/operations/multiobjective/projection_tests.cpp b/tests/operations/multiobjective/projection_tests.cpp
@@ -77,12 +77,12 @@ TEST_F(projection_tests, scale_scaled_fitness_value) {
 
   // assert
   auto values = to_vector(population_.individuals());
-  EXPECT_NEAR(values[0], 120., 0.0000001);
-  EXPECT_NEAR(values[1], 80., 0.0000001);
-  EXPECT_NEAR(values[2], 2.5, 0.0000001);
-  EXPECT_NEAR(values[3], 1.25, 0.0000001);
-  EXPECT_NEAR(values[4], 0.00375, 0.0000001);
-  EXPECT_NEAR(values[5], 0.001875, 0.0000001);
+  EXPECT_NEAR(values[0], 1.4035, 0.0001);
+  EXPECT_NEAR(values[1], 2.8070, 0.0001);
+  EXPECT_NEAR(values[2], 1.0526, 0.0001);
+  EXPECT_NEAR(values[3], 1.2280, 0.0001);
+  EXPECT_NEAR(values[4], 0.9999, 0.0001);
+  EXPECT_NEAR(values[5], 1.0263, 0.0001);
 }
 TEST_F(projection_tests, translate_scaled_fitness_value) {
   // arrange