Changeset 10075 for branches/GrammaticalEvolution/HeuristicLab.Problems.GrammaticalEvolution/Mappers/GenotypeToPhenotypeMapper.cs

Timestamp:

10/21/13 11:29:55 (11 years ago)

Author:

sawinkle

Message:

#2109:

• For each newly created node, ResetLocalParameters() has to be called, if possible. Otherwise 'Variable' symbols won't be initialized correctly. (E.g. internal ValueName is null and causes exceptions.)
• Method MapDepthFirstRecursively() of DepthFirstMapper.cs checks subtree boundaries by using the MinimumArity instead of the MaximumArity. Otherwise e.g. adding the 'Addition' symbol will cause very short trees, because this symbol has got a MaximumArity of 255! This would cause, that the tree is immediately full, after insertion of one 'Addition' symbol, if the genotype length is e.g. just 100.
• Several bug fixes.
• Unresolved issues:
  • Changes in the selected grammar are not taken into account during a run (e.g. 'Addition' symbols will be inserted into the tree, although its checkbox was unchecked previously).
  • Exception, if a division by zero is tried.
  • Wrapping mechanism.

File:

• branches/GrammaticalEvolution/HeuristicLab.Problems.GrammaticalEvolution/Mappers/GenotypeToPhenotypeMapper.cs (modified) (2 diffs)

branches/GrammaticalEvolution/HeuristicLab.Problems.GrammaticalEvolution/Mappers/GenotypeToPhenotypeMapper.cs

@@ -52 +52 @@
     protected ISymbolicExpressionTreeNode GetRandomTerminalNode(ISymbolicExpressionTreeNode parentNode,
                                                               ISymbolicExpressionGrammar grammar) {
-      var possibleSymbolsList = from s in grammar.GetAllowedChildSymbols(parentNode.Symbol)
-                                where s.MaximumArity == 0
-                                where s.MinimumArity == 0
-                                select s;
-      // TODO: Check, if symbol list is empty (no terminal nodes found) - what should happen? 
-      return possibleSymbolsList.SelectRandom(new MersenneTwister()).CreateTreeNode();
+      // only select specific symbols, which can be interpreted ...
+      var possibleSymbolsList = (from s in grammar.GetAllowedChildSymbols(parentNode.Symbol)
+                                 where s.InitialFrequency > 0.0
+                                 where s.MaximumArity == 0
+                                 where s.MinimumArity == 0
+                                 select s).ToList();
+      // TODO: Check, if symbol list is empty (no terminal nodes found) - what should happen?
+      var newNode = possibleSymbolsList.SelectRandom(new MersenneTwister()).CreateTreeNode();
+      if (newNode.HasLocalParameters) newNode.ResetLocalParameters(new MersenneTwister());
+      return newNode;
     }
 
@@ -74 +78 @@
                                                           int genotypeIndex) {
 
-      IEnumerable<ISymbol> symbolList = grammar.GetAllowedChildSymbols(parentNode.Symbol);
+      // only select specific symbols, which can be interpreted ...
+      IEnumerable<ISymbol> symbolList = (from s in grammar.GetAllowedChildSymbols(parentNode.Symbol)
+                                         where s.InitialFrequency > 0.0
+                                         select s).ToList();
       int prodRuleCount = symbolList.Count();
       int prodRuleIndex = genotype[genotypeIndex % genotype.Length] % prodRuleCount;
 
-      return symbolList.ElementAt(prodRuleIndex).CreateTreeNode();
+      var newNode = symbolList.ElementAt(prodRuleIndex).CreateTreeNode();
+      if (newNode.HasLocalParameters) newNode.ResetLocalParameters(new MersenneTwister());
+      return newNode;
     }
   }