Changeset 15277 for stable/HeuristicLab.Encodings.RealVectorEncoding/3.3/ParticleOperators/SPSO2011ParticleUpdater.cs

Timestamp:

07/21/17 11:18:40 (7 years ago)

Author:

abeham

Message:

#2797: merged revisions 15071, 15076, 15091, 15092, 15093, 15096, 15102, 15114, 15181, 15201, 15214, 15223, 15224, 15228 to stable

Location:

stable

Files:

• . (modified) (1 prop)
• HeuristicLab.Encodings.RealVectorEncoding (modified) (1 prop)
• HeuristicLab.Encodings.RealVectorEncoding/3.3/ParticleOperators/SPSO2011ParticleUpdater.cs (copied) (copied from trunk/sources/HeuristicLab.Encodings.RealVectorEncoding/3.3/ParticleOperators/SPSO2011ParticleUpdater.cs) (3 diffs)

stable/HeuristicLab.Encodings.RealVectorEncoding/3.3/ParticleOperators/SPSO2011ParticleUpdater.cs

@@ -25 +25 @@
 using HeuristicLab.Data;
 using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+using HeuristicLab.Random;
 
 namespace HeuristicLab.Encodings.RealVectorEncoding {
   [Item("SPSO 2011 Particle Updater", "Updates the particle's position according to the formulae described in SPSO 2011.")]
   [StorableClass]
-  public sealed class SPSO2011ParticleUpdater : RealVectorParticleUpdater {
-
+  public sealed class SPSO2011ParticleUpdater : SPSOParticleUpdater {
     #region Construction & Cloning
     [StorableConstructor]
@@ -41 +41 @@
     #endregion
     
-    public static void UpdateVelocity(IRandom random, RealVector velocity, double maxVelocity, RealVector position, double inertia, RealVector personalBest, double personalBestAttraction, RealVector neighborBest, double neighborBestAttraction) {
+    public static void UpdateVelocity(IRandom random, RealVector velocity, RealVector position, RealVector personalBest, RealVector neighborBest, double inertia = 0.721, double personalBestAttraction = 1.193, double neighborBestAttraction = 1.193, double maxVelocity = double.MaxValue) {
       var gravity = new double[velocity.Length];
-      var direct = new RealVector(velocity.Length);
+      var direction = new RealVector(velocity.Length);
       var radius = 0.0;
 
+      var nd = new NormalDistributedRandom(random, 0, 1);
+
       for (int i = 0; i < velocity.Length; i++) {
-        var g_id = 1.193 * ((personalBest[i] + neighborBest[i] - 2 * position[i]) / 3.0);
+        var g_id = (personalBestAttraction * personalBest[i]
+          + neighborBestAttraction * neighborBest[i]
+          - position[i] * (neighborBestAttraction + personalBestAttraction)) / 3.0;
+        // center of the hyper-sphere
         gravity[i] = g_id + position[i];
-        direct[i] = (random.NextDouble() - 0.5) * 2;
+        // a random direction vector uniform over the surface of hyper-sphere, see http://mathworld.wolfram.com/HyperspherePointPicking.html
+        direction[i] = nd.NextDouble();
         radius += g_id * g_id;
       }
 
+      // randomly choose a radius within the hyper-sphere
       radius = random.NextDouble() * Math.Sqrt(radius);
 
-      var unitscale = Math.Sqrt(direct.DotProduct(direct));
+      // unitscale is used to rescale the random direction vector to unit length, resp. length of the radius
+      var unitscale = Math.Sqrt(direction.DotProduct(direction));
       if (unitscale > 0) {
         for (var i = 0; i < velocity.Length; i++) {
-          velocity[i] = velocity[i] * inertia + gravity[i] + direct[i] * radius / unitscale - position[i];
+          var sampledPos = gravity[i] + direction[i] * radius / unitscale;
+          velocity[i] = velocity[i] * inertia + sampledPos - position[i];
         }
       }
@@ -101 +110 @@
       var neighborBest = NeighborBestParameter.ActualValue;
       var neighborBestAttraction = NeighborBestAttractionParameter.ActualValue.Value;
-      
-      UpdateVelocity(random, velocity, maxVelocity, position, inertia, personalBest, personalBestAttraction, neighborBest, neighborBestAttraction);
+
+      UpdateVelocity(random, velocity, position, personalBest, neighborBest, inertia, personalBestAttraction, neighborBestAttraction, maxVelocity);
       UpdatePosition(bounds, velocity, position);