Changeset 1196 for branches/CEDMA-Refactoring-Ticket419/HeuristicLab.GP/Recombination/OnePointCrossOver.cs

Timestamp:

02/02/09 12:45:08 (15 years ago)

Author:

gkronber

Message:

fixed #479 (Crossover operators create trees that are larger than the allowed max size)

File:

• branches/CEDMA-Refactoring-Ticket419/HeuristicLab.GP/Recombination/OnePointCrossOver.cs (modified) (4 diffs)

branches/CEDMA-Refactoring-Ticket419/HeuristicLab.GP/Recombination/OnePointCrossOver.cs

@@ -36 +36 @@
   /// W. B. Langdon and R. Poli.  Foundations of Genetic Programming. Springer-Verlag, 2002.
   /// </summary>
-  public class OnePointCrossOver : GPCrossoverBase {
+  public class OnePointCrossOver : SizeConstrictedGPCrossoverBase {
     // internal data structure to represent crossover points
     private class CrossoverPoint {
@@ -45 +45 @@
     public override string Description {
       get {
-        return @"";
+        return @"One point crossover for trees as described in W. B. Langdon and R. Poli. Foundations of Genetic Programming. Springer-Verlag, 2002.";
       }
     }
 
-    internal override IFunctionTree Cross(IScope scope, TreeGardener gardener, MersenneTwister random, IFunctionTree tree0, IFunctionTree tree1) {
+    internal override IFunctionTree Cross(TreeGardener gardener, MersenneTwister random, IFunctionTree tree0, IFunctionTree tree1, int maxTreeSize, int maxTreeHeight) {
       List<CrossoverPoint> allowedCrossOverPoints = new List<CrossoverPoint>();
-      GetCrossOverPoints(gardener, tree0, tree1, allowedCrossOverPoints);
+      GetCrossOverPoints(gardener, tree0, tree1, maxTreeSize - tree0.Size, allowedCrossOverPoints);
       if (allowedCrossOverPoints.Count > 0) {
         CrossoverPoint crossOverPoint = allowedCrossOverPoints[random.Next(allowedCrossOverPoints.Count)];
@@ -62 +62 @@
     }
 
-    private void GetCrossOverPoints(TreeGardener gardener, IFunctionTree branch0, IFunctionTree branch1, List<CrossoverPoint> crossoverPoints) {
+    private void GetCrossOverPoints(TreeGardener gardener, IFunctionTree branch0, IFunctionTree branch1, int maxNewNodes, List<CrossoverPoint> crossoverPoints) {
       if (branch0.SubTrees.Count != branch1.SubTrees.Count) return;
 
       for (int i = 0; i < branch0.SubTrees.Count; i++) {
         // if the current branch can be attached as a sub-tree to branch0
-        if (gardener.GetAllowedSubFunctions(branch0.Function, i).Contains(branch1.SubTrees[i].Function)) {
+        if (gardener.GetAllowedSubFunctions(branch0.Function, i).Contains(branch1.SubTrees[i].Function) &&
+           branch1.SubTrees[i].Size - branch0.SubTrees[i].Size <= maxNewNodes) {
           CrossoverPoint p = new CrossoverPoint();
           p.childIndex = i;
@@ -74 +75 @@
           crossoverPoints.Add(p);
         }
-        GetCrossOverPoints(gardener, branch0.SubTrees[i], branch1.SubTrees[i], crossoverPoints);
+        GetCrossOverPoints(gardener, branch0.SubTrees[i], branch1.SubTrees[i], maxNewNodes, crossoverPoints);
       }
     }