Changeset 7496

Timestamp:

02/21/12 11:03:08 (12 years ago)

Author:

bburlacu

Message:

#1683: Simplified selection of cut points and allowed branches.

File:

• branches/HeuristicLab.Crossovers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Crossovers/SymbolicDataAnalysisExpressionSemanticSimilarityCrossover.cs (modified) (5 diffs)

branches/HeuristicLab.Crossovers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Crossovers/SymbolicDataAnalysisExpressionSemanticSimilarityCrossover.cs

@@ -30 +30 @@
 
 namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
-  [Item("SemanticSimilarityCrossover", "An operator which performs subtree swapping based on the semantic similarity between subtrees.")]
+  [Item("SemanticSimilarityCrossover", "An operator which performs subtree swapping based on the notion semantic similarity between subtrees\n" +
+                                       "(criteria: mean of the absolute differences between the estimated output values of the two subtrees, falling into a user-defined range)\n" +
+                                       "- Take two parent individuals P0 and P1\n" +
+                                       "- Randomly choose a node N from the P0\n" +
+                                       "- Find the first node M that satisfies the semantic similarity criteria\n" +
+                                       "- Swap N for M and return P0")]
   public sealed class SymbolicDataAnalysisExpressionSemanticSimilarityCrossover<T> : SymbolicDataAnalysisExpressionCrossover<T> where T : class, IDataAnalysisProblemData {
     private const string SemanticSimilarityRangeParameterName = "SemanticSimilarityRange";
@@ -52 +57 @@
       : base() {
       Parameters.Add(new ValueLookupParameter<DoubleRange>(SemanticSimilarityRangeParameterName, "Semantic similarity interval.", new DoubleRange(0.0001, 10)));
+      Name = "SemanticSimilarityCrossover";
     }
     public override IDeepCloneable Clone(Cloner cloner) {
@@ -72 +78 @@
       var crossoverPoints0 = new List<CutPoint>();
       parent0.Root.ForEachNodePostfix((n) => {
-        if (n.Subtrees.Any() && n != parent0.Root)
-          foreach (var child in n.Subtrees)
-            crossoverPoints0.Add(new CutPoint(n, child));
+        if (n.Parent != null && n.Parent != parent0.Root)
+          crossoverPoints0.Add(new CutPoint(n.Parent, n));
       });
       var crossoverPoint0 = crossoverPoints0.SelectRandom(random);
@@ -82 +87 @@
       var allowedBranches = new List<ISymbolicExpressionTreeNode>();
       parent1.Root.ForEachNodePostfix((n) => {
-        if (n.Subtrees.Any() && n != parent1.Root)
-          allowedBranches.AddRange(n.Subtrees.Where(s => crossoverPoint0.IsMatchingPointType(s) && s.GetDepth() + level <= maxDepth && s.GetLength() + length <= maxLength));
+        if (n.Parent != null && n.Parent != parent1.Root) {
+          if (n.GetDepth() + level <= maxDepth && n.GetLength() + length <= maxLength && crossoverPoint0.IsMatchingPointType(n))
+            allowedBranches.Add(n);
+        }
       });
 
@@ -117 +124 @@
       // perform the actual swap
       if (selectedBranch != null)
-        swap(crossoverPoint0, selectedBranch);
-
+        Swap(crossoverPoint0, selectedBranch);
       return parent0;
-    }
-
-    private static void swap(CutPoint crossoverPoint, ISymbolicExpressionTreeNode selectedBranch) {
-      // perform the actual swap
-      if (crossoverPoint.Child != null) {
-        // manipulate the tree of parent0 in place
-        // replace the branch in tree0 with the selected branch from tree1
-        crossoverPoint.Parent.RemoveSubtree(crossoverPoint.ChildIndex);
-        if (selectedBranch != null) {
-          crossoverPoint.Parent.InsertSubtree(crossoverPoint.ChildIndex, selectedBranch);
-        }
-      } else {
-        // child is null (additional child should be added under the parent)
-        if (selectedBranch != null) {
-          crossoverPoint.Parent.AddSubtree(selectedBranch);
-        }
-      }
     }
   }