Changeset 7495

Timestamp:

02/21/12 11:01:02 (12 years ago)

Author:

bburlacu

Message:

#1693:

• Simplified selection of cutpoints and reordered criteria for cutpoint selection

File:

• branches/HeuristicLab.Crossovers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Crossovers/SymbolicDataAnalysisExpressionContextAwareCrossover.cs (modified) (6 diffs)

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

@@ -30 +30 @@
 namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
 
-  [Item("ContextAwareCrossover", "An operator which deterministically choses the best insertion point for a randomly selected node.")]
+  [Item("ContextAwareCrossover", "An operator which deterministically choses the best insertion point for a randomly selected node:\n" +
+                                 "- Take two parent individuals P0 and P1\n" +
+                                 "- Randomly choose a node N from P1\n" +
+                                 "- Test all crossover points from P0 to determine the best location for N to be inserted")]
   public sealed class SymbolicDataAnalysisExpressionContextAwareCrossover<T> : SymbolicDataAnalysisExpressionCrossover<T> where T : class, IDataAnalysisProblemData {
     [StorableConstructor]
@@ -63 +66 @@
       var possibleChildren = new List<ISymbolicExpressionTreeNode>();
       parent1.Root.ForEachNodePostfix((n) => {
-        if (n.Subtrees.Any() && n != parent0.Root)
-          possibleChildren.AddRange(n.Subtrees);
+        if (n.Parent != null && n.Parent != parent1.Root)
+          possibleChildren.Add(n);
       });
       var selectedChild = possibleChildren.SelectRandom(random);
@@ -71 +74 @@
 
       parent0.Root.ForEachNodePostfix((n) => {
-        if (n.Subtrees.Any() && n != parent0.Root)
-          crossoverPoints.AddRange(from s in n.Subtrees
-                                   let crossoverPoint = new CutPoint(n, s)
-                                   let totalDepth = parent0.Root.GetBranchLevel(s) + selectedChild.GetDepth()
-                                   let totalLength = parent0.Root.GetLength() - s.GetLength() + selectedChild.GetLength()
-                                   where crossoverPoint.IsMatchingPointType(selectedChild) && totalDepth <= maxDepth && totalLength <= maxLength
-                                   select crossoverPoint);
+        if (n.Parent != null && n.Parent != parent0.Root) {
+          var totalDepth = parent0.Root.GetBranchLevel(n) + selectedChild.GetDepth();
+          var totalLength = parent0.Root.GetLength() - n.GetLength() + selectedChild.GetLength();
+          if (totalDepth <= maxDepth && totalLength <= maxLength) {
+            var crossoverPoint = new CutPoint(n.Parent, n);
+            if (crossoverPoint.IsMatchingPointType(selectedChild))
+              crossoverPoints.Add(crossoverPoint);
+          }
+        }
       });
 
@@ -86 +91 @@
           var parent = selectedChild.Parent;
           // perform a swap and check the quality of the solution
-          swap(crossoverPoint, selectedChild);
+          Swap(crossoverPoint, selectedChild);
           double quality = evaluator.Evaluate(context, parent0, problemData, rows);
           qualities.Add(new Tuple<CutPoint, double>(crossoverPoint, quality));
@@ -92 +97 @@
           selectedChild.Parent = parent;
           // swap the replaced subtree back into the tree so that the structure is preserved
-          swap(crossoverPoint, crossoverPoint.Child);
+          Swap(crossoverPoint, crossoverPoint.Child);
         }
 
@@ -99 +104 @@
         // swap the node that would create the best offspring
         // this last swap makes a total of (2 * crossoverPoints.Count() + 1) swap operations.
-        swap(crossoverPoint0, selectedChild);
+        Swap(crossoverPoint0, selectedChild);
       }
 
       return parent0;
     }
-
-    private static void swap(CutPoint crossoverPoint, ISymbolicExpressionTreeNode selectedBranch) {
-      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);
-        }
-      }
-    }
   }
 }