Changeset 4524 for trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding

Timestamp:

09/27/10 17:31:09 (14 years ago)

Author:

gkronber

Message:

Fixed #1214. The size of the manipulated tree is checked and only if the new tree fulfills the size requirements it is accepted otherwise the original tree is returned instead. Additionally the calculation of tree sizes is checked for overflows now.

Location:

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.3

Files:

• ArchitectureManipulators/ArgumentCreater.cs (modified) (7 diffs)
• ArchitectureManipulators/ArgumentDuplicater.cs (modified) (2 diffs)
• SymbolicExpressionTreeNode.cs (modified) (1 diff)
• Tests/Util.cs (modified) (1 diff)

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.3/ArchitectureManipulators/ArgumentCreater.cs

@@ -26 +26 @@
 using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Symbols;
 using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+using System;
 
 namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.ArchitectureManipulators {
@@ -51 +52 @@
       int maxTreeSize, int maxTreeHeight,
       int maxFunctionDefiningBranches, int maxFunctionArguments) {
+      // work on a copy in case we find out later that the tree would be too big
+      // in this case it's easiest to simply return the original tree.
+      SymbolicExpressionTree clonedTree = (SymbolicExpressionTree)symbolicExpressionTree.Clone();
 
-      var functionDefiningBranches = symbolicExpressionTree.IterateNodesPrefix().OfType<DefunTreeNode>();
-
+      var functionDefiningBranches = clonedTree.IterateNodesPrefix().OfType<DefunTreeNode>();
       if (functionDefiningBranches.Count() == 0)
         // no function defining branch found => abort
@@ -65 +68 @@
         // max number of arguments reached => abort
         return false;
+
+      var allowedArgumentIndexes = Enumerable.Range(0, maxFunctionArguments);
+      var newArgumentIndex = allowedArgumentIndexes.Except(definedArguments).First();
+      ArgumentTreeNode newArgumentNode = MakeArgumentNode(newArgumentIndex);
+
+      // this operation potentially creates very big trees so the access to the size property might throw overflow exception
+      try {
+        if (CreateNewArgumentForDefun(random, clonedTree, selectedDefunBranch, newArgumentNode) && clonedTree.Size < maxTreeSize && clonedTree.Height < maxTreeHeight) {
+
+          // size constraints are fulfilled 
+          // replace root of original tree with root of manipulated tree
+          symbolicExpressionTree.Root = clonedTree.Root;
+          return true;
+        } else {
+          // keep originalTree
+          return false;
+        }
+      }
+      catch (OverflowException) {
+        // keep original tree
+        return false;
+      }
+    }
+
+
+    private static bool CreateNewArgumentForDefun(IRandom random, SymbolicExpressionTree tree, DefunTreeNode defunBranch, ArgumentTreeNode newArgumentNode) {
       // select a random cut point in the function defining branch
       // the branch at the cut point is to be replaced by a new argument node
-      var cutPoints = (from node in selectedDefunBranch.IterateNodesPrefix()
+      var cutPoints = (from node in defunBranch.IterateNodesPrefix()
                        where node.SubTrees.Count > 0
                        from subtree in node.SubTrees
@@ -76 +105 @@
         return false;
       var selectedCutPoint = cutPoints[random.Next(cutPoints.Count)];
-      var allowedArgumentIndexes = Enumerable.Range(0, maxFunctionArguments);
-      var newArgumentIndex = allowedArgumentIndexes.Except(definedArguments).First();
       // replace the branch at the cut point with an argument node
-      var newArgNode = MakeArgumentNode(newArgumentIndex);
       var replacedBranch = selectedCutPoint.ReplacedChild;
       selectedCutPoint.Parent.RemoveSubTree(selectedCutPoint.ReplacedChildIndex);
-      selectedCutPoint.Parent.InsertSubTree(selectedCutPoint.ReplacedChildIndex, newArgNode);
+      selectedCutPoint.Parent.InsertSubTree(selectedCutPoint.ReplacedChildIndex, newArgumentNode);
 
-      // find all invocations of the selected ADF and attach a cloned version of the replaced branch (with all argument-nodes expanded)
-      var invocationNodes = (from node in symbolicExpressionTree.IterateNodesPrefix().OfType<InvokeFunctionTreeNode>()
-                             where node.Symbol.FunctionName == selectedDefunBranch.FunctionName
-                             where node.SubTrees.Count == selectedDefunBranch.NumberOfArguments
+      // find all old invocations of the selected ADF and attach a cloned version of the replaced branch (with all argument-nodes expanded)
+      // iterate in post-fix order to make sure that the subtrees of n are already adapted when n is processed
+      var invocationNodes = (from node in tree.IterateNodesPostfix().OfType<InvokeFunctionTreeNode>()
+                             where node.Symbol.FunctionName == defunBranch.FunctionName
+                             where node.SubTrees.Count == defunBranch.NumberOfArguments
                              select node).ToList();
       // do this repeatedly until no matching invocations are found      
-      while (invocationNodes.Count() > 0) {
+      while (invocationNodes.Count > 0) {
         List<SymbolicExpressionTreeNode> newlyAddedBranches = new List<SymbolicExpressionTreeNode>();
         foreach (var invocationNode in invocationNodes) {
+          // check that the invocation node really has the correct number of arguments
+          if (invocationNode.SubTrees.Count != defunBranch.NumberOfArguments) throw new InvalidOperationException();
           // append a new argument branch after expanding all argument nodes
           var clonedBranch = (SymbolicExpressionTreeNode)replacedBranch.Clone();
           clonedBranch = ReplaceArgumentsInBranch(clonedBranch, invocationNode.SubTrees);
-          invocationNode.InsertSubTree(newArgumentIndex, clonedBranch);
+          invocationNode.InsertSubTree(newArgumentNode.Symbol.ArgumentIndex, clonedBranch);
           newlyAddedBranches.Add(clonedBranch);
         }
+        // iterate in post-fix order to make sure that the subtrees of n are already adapted when n is processed
         invocationNodes = (from newlyAddedBranch in newlyAddedBranches
-                           from node in newlyAddedBranch.IterateNodesPrefix().OfType<InvokeFunctionTreeNode>()
-                           where node.Symbol.FunctionName == selectedDefunBranch.FunctionName
-                           where node.SubTrees.Count == selectedDefunBranch.NumberOfArguments
+                           from node in newlyAddedBranch.IterateNodesPostfix().OfType<InvokeFunctionTreeNode>()
+                           where node.Symbol.FunctionName == defunBranch.FunctionName
+                           where node.SubTrees.Count == defunBranch.NumberOfArguments
                            select node).ToList();
       }
@@ -108 +138 @@
       // it's possible that the number of actually referenced arguments was reduced (all references were replaced by a single new argument)
       // but the number of expected arguments is increased anyway
-      selectedDefunBranch.NumberOfArguments++;
-      selectedDefunBranch.Grammar.AddSymbol(newArgNode.Symbol);
-      selectedDefunBranch.Grammar.SetMinSubtreeCount(newArgNode.Symbol, 0);
-      selectedDefunBranch.Grammar.SetMaxSubtreeCount(newArgNode.Symbol, 0);
+      defunBranch.NumberOfArguments++;
+      defunBranch.Grammar.AddSymbol(newArgumentNode.Symbol);
+      defunBranch.Grammar.SetMinSubtreeCount(newArgumentNode.Symbol, 0);
+      defunBranch.Grammar.SetMaxSubtreeCount(newArgumentNode.Symbol, 0);
       // allow the argument as child of any other symbol
-      foreach (var symb in selectedDefunBranch.Grammar.Symbols)
-        for (int i = 0; i < selectedDefunBranch.Grammar.GetMaxSubtreeCount(symb); i++) {
-          selectedDefunBranch.Grammar.SetAllowedChild(symb, newArgNode.Symbol, i);
+      foreach (var symb in defunBranch.Grammar.Symbols)
+        for (int i = 0; i < defunBranch.Grammar.GetMaxSubtreeCount(symb); i++) {
+          defunBranch.Grammar.SetAllowedChild(symb, newArgumentNode.Symbol, i);
         }
-      foreach (var subtree in symbolicExpressionTree.Root.SubTrees) {
+      foreach (var subtree in tree.Root.SubTrees) {
         // when the changed function is known in the branch then update the number of arguments
-        var matchingSymbol = subtree.Grammar.Symbols.OfType<InvokeFunction>().Where(s => s.FunctionName == selectedDefunBranch.FunctionName).SingleOrDefault();
+        var matchingSymbol = subtree.Grammar.Symbols.OfType<InvokeFunction>().Where(s => s.FunctionName == defunBranch.FunctionName).SingleOrDefault();
         if (matchingSymbol != null) {
-          subtree.Grammar.SetMinSubtreeCount(matchingSymbol, selectedDefunBranch.NumberOfArguments);
-          subtree.Grammar.SetMaxSubtreeCount(matchingSymbol, selectedDefunBranch.NumberOfArguments);
+          subtree.Grammar.SetMinSubtreeCount(matchingSymbol, defunBranch.NumberOfArguments);
+          subtree.Grammar.SetMaxSubtreeCount(matchingSymbol, defunBranch.NumberOfArguments);
           foreach (var child in subtree.GetAllowedSymbols(0)) {
             for (int i = 0; i < subtree.Grammar.GetMaxSubtreeCount(matchingSymbol); i++) {
@@ -130 +160 @@
         }
       }
+
       return true;
     }
 
     private static SymbolicExpressionTreeNode ReplaceArgumentsInBranch(SymbolicExpressionTreeNode branch, IList<SymbolicExpressionTreeNode> argumentTrees) {
-      if (branch is ArgumentTreeNode) {
-        var argNode = branch as ArgumentTreeNode;
+      ArgumentTreeNode argNode = branch as ArgumentTreeNode;
+      if (argNode != null) {
         // replace argument nodes by a clone of the original subtree that provided the result for the argument node
         return (SymbolicExpressionTreeNode)argumentTrees[argNode.Symbol.ArgumentIndex].Clone();
@@ -149 +180 @@
     }
 
-    private static SymbolicExpressionTreeNode MakeArgumentNode(int argIndex) {
+    private static ArgumentTreeNode MakeArgumentNode(int argIndex) {
       var node = (ArgumentTreeNode)(new Argument(argIndex)).CreateTreeNode();
       return node;

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.3/ArchitectureManipulators/ArgumentDuplicater.cs

@@ -26 +26 @@
 using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
 using System.Collections.Generic;
+using System;
 
 namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.ArchitectureManipulators {
@@ -87 +88 @@
         List<SymbolicExpressionTreeNode> newlyAddedBranches = new List<SymbolicExpressionTreeNode>();
         foreach (var invokeNode in invocationNodes) {
+          // check that the invocation node really has the correct number of arguments
+          if (invokeNode.SubTrees.Count != selectedDefunBranch.NumberOfArguments) throw new InvalidOperationException();
           var argumentBranch = invokeNode.SubTrees[selectedArgumentSymbol.ArgumentIndex];
           var clonedArgumentBranch = (SymbolicExpressionTreeNode)argumentBranch.Clone();

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.3/SymbolicExpressionTreeNode.cs

@@ -94 +94 @@
         size = 1;
         if (SubTrees != null) {
-          for (int i = 0; i < SubTrees.Count; i++) size += (short)SubTrees[i].GetSize();
+          for (int i = 0; i < SubTrees.Count; i++) {
+            checked { size += (short)SubTrees[i].GetSize(); }
+          }
         }
         return size;

trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.3/Tests/Util.cs

@@ -115 +115 @@
 
     public static void IsValid(SymbolicExpressionTree tree) {
+      int reportedSize = tree.Size;
+      int actualSize = tree.IterateNodesPostfix().Count();
+      Assert.AreEqual(actualSize, reportedSize);
+
       foreach (var defunTreeNode in tree.Root.SubTrees.OfType<DefunTreeNode>()) {
         int arity = defunTreeNode.NumberOfArguments;