Changeset 1209

Timestamp:

02/05/09 12:56:43 (15 years ago)

Author:

gkronber

Message:

Return the parent tree without changes if it's not possible to create a valid tree within the size constraints after N tries. #479 (Crossover operators create trees that are larger than the allowed max size)

File:

• branches/CEDMA-Refactoring-Ticket419/HeuristicLab.GP/Recombination/SizeConstrictedGPCrossoverBase.cs (modified) (2 diffs)

branches/CEDMA-Refactoring-Ticket419/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;