Changeset 1212

Timestamp:

02/10/09 12:59:37 (15 years ago)

Author:

gkronber

Message:

merged r1200 and r1209 from CEDMA refactoring branch into trunk. #479 (Crossover operators create trees that are larger than the allowed max size)

Location:

trunk/sources/HeuristicLab.GP/Recombination

Files:

• SizeConstrictedGPCrossoverBase.cs (modified) (2 diffs)
• SizeFairCrossOver.cs (modified) (1 diff)

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

@@ -50 +50 @@
       int tries = 0;
       do {
+        if (tries++ > MaxRecombinationTries)
+          // if after so many tries it was not possible to create a solution within the given size constraints just return the tree without changes.
+          return tree0;
         if (tree0.SubTrees.Count > 0) {
           newTree = Cross(gardener, random, (IFunctionTree)tree0.Clone(), (IFunctionTree)tree1.Clone(), maxTreeSize, maxTreeHeight);
@@ -55 +58 @@
           newTree = Cross(gardener, random, (IFunctionTree)tree1.Clone(), (IFunctionTree)tree0.Clone(), maxTreeSize, maxTreeHeight);
         } else newTree = tree0;
-        if (tries++ > MaxRecombinationTries)
-          throw new InvalidOperationException("Couldn't recombine parents to create a valid child not larger than " + maxTreeSize + " and not higher than " + maxTreeHeight + ".");
       } while (newTree.Size > maxTreeSize || newTree.Height > maxTreeHeight);
       return newTree;

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

@@ -83 +83 @@
       if (shorterBranches.Count > 0 && longerBranches.Count > 0) {
         double pEqualLength = equalLengthBranches.Count > 0 ? 1.0 / removedBranchSize : 0.0;
-        double pLonger = (1.0 - pEqualLength) / (longerBranches.Count * (1.0 + longerBranches.Average(p => p.branchSize) / shorterBranches.Average(p => p.branchSize)));
+        double pLonger;
+        if (parent.Size == maxTreeSize) {
+          pLonger = 0.0;
+        } else {
+          pLonger = (1.0 - pEqualLength) / (longerBranches.Count * (1.0 + longerBranches.Average(p => p.branchSize) / shorterBranches.Average(p => p.branchSize)));
+        }
         double pShorter = (1.0 - pEqualLength - pLonger);