Changeset 807

Timestamp:

11/23/08 19:29:26 (16 years ago)

Author:

gkronber

Message:

Changed UniformCrossover to create two new trees from two parents. This shouldn't alter the search behavior because UniformCrossover is symmetric. #382 (Uniform crossover operator for GP)

File:

• trunk/sources/HeuristicLab.GP/Recombination/UniformCrossover.cs (modified) (2 diffs)

trunk/sources/HeuristicLab.GP/Recombination/UniformCrossover.cs

@@ -62 +62 @@
       CompositeOperation initOperations = new CompositeOperation();
 
-      int children = scope.SubScopes.Count / 2;
-      for (int i = 0; i < children; i++) {
+      int crossoverEvents = scope.SubScopes.Count / 2;
+      for (int i = 0; i < crossoverEvents; i++) {
         IScope parent1 = scope.SubScopes[0];
         scope.RemoveSubScope(parent1);
         IScope parent2 = scope.SubScopes[0];
         scope.RemoveSubScope(parent2);
-        IScope child = new Scope(i.ToString());
-        IOperation childInitOperation = Cross(scope, random, gardener, parent1, parent2, child);
-        initOperations.AddOperation(childInitOperation);
-        scope.AddSubScope(child);
-      }
-
-      return initOperations;
-    }
-
-    private IOperation Cross(IScope scope, MersenneTwister random, TreeGardener gardener, IScope parent1, IScope parent2, IScope child) {
-      IFunctionTree newTree = Cross(random, gardener, parent1, parent2);
-      Debug.Assert(gardener.IsValidTree(newTree));
-      int newTreeSize = newTree.Size;
-      int newTreeHeight = newTree.Height;
-      child.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("FunctionTree"), newTree));
-      child.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeSize"), new IntData(newTreeSize)));
-      child.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeHeight"), new IntData(newTreeHeight)));
+        IScope child0 = new Scope((i*2).ToString());
+        IScope child1 = new Scope((i*2+1).ToString());
+        Cross(scope, random, gardener, parent1, parent2, child0, child1);
+        scope.AddSubScope(child0);
+        scope.AddSubScope(child1);
+      }
 
       return null;
     }
 
-
-    private IFunctionTree Cross(MersenneTwister random, TreeGardener gardener, IScope f, IScope g) {
+    private void Cross(IScope scope, MersenneTwister random, TreeGardener gardener, IScope parent1, IScope parent2, IScope child0, IScope child1) {
+      IFunctionTree childTree0;
+      IFunctionTree childTree1;
+      Cross(random, gardener, parent1, parent2, out childTree0, out childTree1);
+      Debug.Assert(gardener.IsValidTree(childTree0));
+      Debug.Assert(gardener.IsValidTree(childTree1));
+      child0.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("FunctionTree"), childTree0));
+      child0.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeSize"), new IntData(childTree0.Size)));
+      child0.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeHeight"), new IntData(childTree0.Height)));
+
+      child1.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("FunctionTree"), childTree1));
+      child1.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeSize"), new IntData(childTree1.Size)));
+      child1.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeHeight"), new IntData(childTree1.Height)));
+    }
+
+
+    private void Cross(MersenneTwister random, TreeGardener gardener, IScope f, IScope g, out IFunctionTree child0, out IFunctionTree child1) {
       IFunctionTree tree0 = f.GetVariableValue<IFunctionTree>("FunctionTree", false);
       int tree0Height = f.GetVariableValue<IntData>("TreeHeight", false).Data;
@@ -155 +159 @@
         }
       }
-      if (random.NextDouble() < 0.5) return tree0; else return tree1;
+      if (random.NextDouble() < 0.5) {
+        child0 = tree0;
+        child1 = tree1;
+      } else {
+        child0 = tree1;
+        child1 = tree0;
+      }
     }