Changeset 2730

Timestamp:

02/01/10 16:43:56 (14 years ago)

Author:

gkronber

Message:

Made PTC2 operator more robust. #859 (PTC2 initialization operator fails if it is used with restrictive function libraries)

Location:

trunk/sources

Files:

• HeuristicLab.GP.Operators/3.3/Initialization/ProbabilisticTreeCreator.cs (modified) (3 diffs)
• HeuristicLab.GP/3.3/TreeGardener.cs (modified) (2 diffs)

trunk/sources/HeuristicLab.GP.Operators/3.3/Initialization/ProbabilisticTreeCreator.cs

@@ -24 +24 @@
 using HeuristicLab.Random;
 using HeuristicLab.GP.Interfaces;
+using System;
 
 namespace HeuristicLab.GP.Operators {
@@ -58 +59 @@
     public static IFunctionTree Create(IRandom random, FunctionLibrary funLib, int minSize, int maxSize, int maxHeight) {
       int treeSize = random.Next(minSize, maxSize);
-      IFunctionTree root;
+      IFunctionTree root = null;
       int tries = 0;
       TreeGardener gardener = new TreeGardener(random, funLib);
       do {
-        root = gardener.PTC2(treeSize, maxHeight);
+        try {
+          root = gardener.PTC2(treeSize, maxHeight);
+        }
+        catch (ArgumentException) {
+          // try a different size
+          treeSize = random.Next(minSize, maxSize);
+          tries = 0;
+        }
         if (tries++ >= MAX_TRIES) {
           // try a different size
@@ -68 +76 @@
           tries = 0;
         }
-      } while (root.GetSize() > maxSize || root.GetHeight() > maxHeight);
+      } while (root == null || root.GetSize() > maxSize || root.GetHeight() > maxHeight);
       return root;
     }

trunk/sources/HeuristicLab.GP/3.3/TreeGardener.cs

@@ -483 +483 @@
 
     public static IFunction RandomSelect(IRandom random, IList<IFunction> functionSet) {
+      if (random == null || functionSet == null) throw new ArgumentNullException();
+      if (functionSet.Count == 0) throw new ArgumentException("Empty function set");
+      if (functionSet.Select(x => x.Tickets).Sum() <= 0) throw new ArgumentException("All functions in set have 0 tickets");
       double[] accumulatedTickets = new double[functionSet.Count];
       double ticketAccumulator = 0;
@@ -498 +501 @@
         if (r < accumulatedTickets[i]) return functionSet[i];
       }
-      // sanity check
-      throw new InvalidProgramException(); // should never happen
+      throw new ArgumentException();
     }