Changeset 7961 for trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Creators/GrowTreeCreator.cs

Timestamp:

06/05/12 10:02:25 (12 years ago)

Author:

bburlacu

Message:

#1866: Fixed bug where initial frequencies of grammar symbols were not taken into account by the tree creators.

File:

• trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Creators/GrowTreeCreator.cs (modified) (3 diffs)

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Creators/GrowTreeCreator.cs

@@ -160 +160 @@
           .Where(s => seedNode.Grammar.IsAllowedChildSymbol(seedNode.Symbol, s, i))
           .ToList();
-        var selectedSymbol = possibleSymbols.SelectRandom(random);
+        var weights = possibleSymbols.Select(s => s.InitialFrequency).ToList();
+        var selectedSymbol = possibleSymbols.SelectRandom(weights, random);
         var tree = selectedSymbol.CreateTreeNode();
         if (tree.HasLocalParameters) tree.ResetLocalParameters(random);
@@ -178 +179 @@
         throw new ArgumentException("Cannot grow node of arity zero. Expected a function node.");
 
-      var allowedSymbols = root.Grammar.AllowedSymbols
-        .Where(s => s.InitialFrequency > 0.0)
-        .ToList();
+      var allowedSymbols = root.Grammar.AllowedSymbols.Where(s => s.InitialFrequency > 0.0).ToList();
 
       for (var i = 0; i < arity; i++) {
@@ -187 +186 @@
             root.Grammar.GetMinimumExpressionDepth(s) - 1 <= maxDepth - currentDepth)
           .ToList();
+
         if (!possibleSymbols.Any())
           throw new InvalidOperationException("No symbols are available for the tree.");
-        var selectedSymbol = possibleSymbols.SelectRandom(random);
+        var weights = possibleSymbols.Select(s => s.InitialFrequency).ToList();
+        var selectedSymbol = possibleSymbols.SelectRandom(weights, random);
         var tree = selectedSymbol.CreateTreeNode();
         if (tree.HasLocalParameters) tree.ResetLocalParameters(random);