/// <summary>
/// Remove, Replace or Insert subtrees
/// </summary>
/// <param name="tree">The symbolic expression tree</param>
/// <param name="parent">The insertion point (ie, the parent node who will receive a new child)</param>
/// <param name="oldChild">The subtree to be replaced</param>
/// <param name="newChild">The replacement subtree</param>
/// <param name="removeSubtree">Flag used to indicate if whole subtrees should be removed (default behavior), or just the subtree root</param>
private void Modify(ISymbolicExpressionTree tree, ISymbolicExpressionTreeNode parent,
ISymbolicExpressionTreeNode oldChild, ISymbolicExpressionTreeNode newChild, bool removeSubtree = true)
{
if (oldChild == null && newChild == null)
{
throw new ArgumentNullException("Cannot deduce operation type from the arguments. Please provide non null operands.");
}
if (oldChild == null)
{
// insertion operation
parent.AddSubtree(newChild);
newChild.Parent = parent;
}
else if (newChild == null)
{
// removal operation
parent.RemoveSubtree(parent.IndexOfSubtree(oldChild));
if (!removeSubtree)
{
for (int i = oldChild.SubtreeCount - 1; i >= 0; --i)
{
var subtree = oldChild.GetSubtree(i);
oldChild.RemoveSubtree(i);
parent.AddSubtree(subtree);
}
}
}
else
{
// replacement operation
var replacementIndex = parent.IndexOfSubtree(oldChild);
parent.RemoveSubtree(replacementIndex);
parent.InsertSubtree(replacementIndex, newChild);
newChild.Parent = parent;
if (changedNodes.ContainsKey(oldChild))
{
changedNodes.Add(newChild, changedNodes[oldChild]); // so that on double click the original node is restored
changedNodes.Remove(oldChild);
}
else
{
changedNodes.Add(newChild, oldChild);
}
}
treeState = IsValid(tree) ? TreeState.Valid : TreeState.Invalid;
switch (treeState)
{
case TreeState.Valid:
this.grpViewHost.Enabled = true;
UpdateModel(Content.Model.SymbolicExpressionTree);
break;
case TreeState.Invalid:
this.grpViewHost.Enabled = false;
break;
}
}
private void SwitchNode(ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode oldBranch, ISymbolicExpressionTreeNode newBranch)
{
for (int i = 0; i < root.SubtreeCount; i++)
{
if (root.GetSubtree(i) == oldBranch)
{
root.RemoveSubtree(i);
root.InsertSubtree(i, newBranch);
return;
}
}
}
private void SwitchNodeWithReplacementNode(ISymbolicExpressionTreeNode parent, int subTreeIndex)
{
ISymbolicExpressionTreeNode subTree = parent.GetSubtree(subTreeIndex);
if (foldedNodes.ContainsKey(subTree))
{
parent.RemoveSubtree(subTreeIndex);
var replacementNode = foldedNodes[subTree];
parent.InsertSubtree(subTreeIndex, replacementNode);
// exchange key and value
foldedNodes.Remove(subTree);
foldedNodes.Add(replacementNode, subTree);
}
}
protected static ISymbolicExpressionTreeNode GenerateAndInsertNewSubtree(IRandom random, ISymbolicExpressionTreeNode parent, List <ISymbol> allowedSymbols, int childIndex, int maxLength, int maxDepth)
{
var weights = allowedSymbols.Select(s => s.InitialFrequency).ToList();
#pragma warning disable 612, 618
var seedSymbol = allowedSymbols.SelectRandom(weights, random);
#pragma warning restore 612, 618
// replace the old node with the new node
var seedNode = seedSymbol.CreateTreeNode();
if (seedNode.HasLocalParameters)
{
seedNode.ResetLocalParameters(random);
}
parent.RemoveSubtree(childIndex);
parent.InsertSubtree(childIndex, seedNode);
ProbabilisticTreeCreator.PTC2(random, seedNode, maxLength, maxDepth);
return(seedNode);
}
/// <summary>
/// Remove, Replace or Insert subtrees
/// </summary>
/// <param name="tree">The symbolic expression tree</param>
/// <param name="parent">The insertion point (ie, the parent node who will receive a new child)</param>
/// <param name="oldChild">The subtree to be replaced</param>
/// <param name="newChild">The replacement subtree</param>
/// <param name="removeSubtree">Flag used to indicate if whole subtrees should be removed (default behavior), or just the subtree root</param>
private void Modify(ISymbolicExpressionTree tree, ISymbolicExpressionTreeNode parent,
ISymbolicExpressionTreeNode oldChild, ISymbolicExpressionTreeNode newChild, bool removeSubtree = true) {
if (oldChild == null && newChild == null)
throw new ArgumentNullException("Cannot deduce operation type from the arguments. Please provide non null operands.");
if (oldChild == null) {
// insertion operation
parent.AddSubtree(newChild);
newChild.Parent = parent;
} else if (newChild == null) {
// removal operation
parent.RemoveSubtree(parent.IndexOfSubtree(oldChild));
if (!removeSubtree) {
for (int i = oldChild.SubtreeCount - 1; i >= 0; --i) {
var subtree = oldChild.GetSubtree(i);
oldChild.RemoveSubtree(i);
parent.AddSubtree(subtree);
}
}
} else {
// replacement operation
var replacementIndex = parent.IndexOfSubtree(oldChild);
parent.RemoveSubtree(replacementIndex);
parent.InsertSubtree(replacementIndex, newChild);
newChild.Parent = parent;
if (changedNodes.ContainsKey(oldChild)) {
changedNodes.Add(newChild, changedNodes[oldChild]); // so that on double click the original node is restored
changedNodes.Remove(oldChild);
} else {
changedNodes.Add(newChild, oldChild);
}
}
treeState = IsValid(tree) ? TreeState.Valid : TreeState.Invalid;
switch (treeState) {
case TreeState.Valid:
this.grpViewHost.Enabled = true;
UpdateModel(Content.Model.SymbolicExpressionTree);
break;
case TreeState.Invalid:
this.grpViewHost.Enabled = false;
break;
}
}
private static void ReplaceWithMinimalTree(IRandom random, ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode parent,
int childIndex)
{
// determine possible symbols that will lead to the smallest possible tree
var possibleSymbols = (from s in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, childIndex)
where s.InitialFrequency > 0.0
group s by parent.Grammar.GetMinimumExpressionLength(s) into g
orderby g.Key
select g).First().ToList();
var weights = possibleSymbols.Select(x => x.InitialFrequency).ToList();
#pragma warning disable 612, 618
var selectedSymbol = possibleSymbols.SelectRandom(weights, random);
#pragma warning restore 612, 618
var tree = selectedSymbol.CreateTreeNode();
if (tree.HasLocalParameters)
{
tree.ResetLocalParameters(random);
}
parent.RemoveSubtree(childIndex);
parent.InsertSubtree(childIndex, tree);
var topLevelNode = tree as SymbolicExpressionTreeTopLevelNode;
if (topLevelNode != null)
{
topLevelNode.SetGrammar((ISymbolicExpressionTreeGrammar)root.Grammar.Clone());
}
for (int i = 0; i < tree.Grammar.GetMinimumSubtreeCount(tree.Symbol); i++)
{
// insert a dummy sub-tree and add the pending extension to the list
var dummy = new SymbolicExpressionTreeNode();
tree.AddSubtree(dummy);
// replace the just inserted dummy by recursive application
ReplaceWithMinimalTree(random, root, tree, i);
}
}
/// <summary>
/// 1. find a mutation point
/// 2. generate new random tree
/// 3. calculate semantic of old and new subtree (or of the closest parent)
/// 4. do mutation if semantically different
/// 5. retry until a certain number of tries is reached
///
/// if no mutation has happened, do random mutation
/// </summary>
public static void ReplaceSemanticallyDifferentBranch(IRandom random, ISymbolicExpressionTree symbolicExpressionTree, ICFGPythonProblemData problemData, ItemArray <PythonStatementSemantic> semantics, PythonProcess pythonProcess, double timeout, int maxTreeLength, int maxTreeDepth, int maximumSemanticTries)
{
if (semantics == null || semantics.Length == 0)
{
ReplaceBranchManipulation.ReplaceRandomBranch(random, symbolicExpressionTree, maxTreeLength, maxTreeDepth);
return;
}
var statementProductionNames = SemanticOperatorHelper.GetSemanticProductionNames(symbolicExpressionTree.Root.Grammar);
var variables = problemData.Variables.GetVariableNames().ToList();
string variableSettings = problemData.VariableSettings.Count == 0 ? String.Empty : String.Join(Environment.NewLine, problemData.VariableSettings.Select(x => x.Value));
var allowedSymbols = new List <ISymbol>();
// repeat until a fitting parent and child are found (MAX_TRIES times)
int tries = 0;
int semanticTries = 0;
do
{
#region find mutation point
#pragma warning disable 612, 618
ISymbolicExpressionTreeNode parent = symbolicExpressionTree.Root.IterateNodesPrefix().Skip(1).Where(n => n.SubtreeCount > 0).SelectRandom(random);
#pragma warning restore 612, 618
int childIndex = random.Next(parent.SubtreeCount);
var child = parent.GetSubtree(childIndex);
int maxLength = maxTreeLength - symbolicExpressionTree.Length + child.GetLength();
int maxDepth = maxTreeDepth - symbolicExpressionTree.Root.GetBranchLevel(child);
allowedSymbols.Clear();
foreach (var symbol in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, childIndex))
{
// check basic properties that the new symbol must have
if ((symbol.Name != child.Symbol.Name || symbol.MinimumArity > 0) &&
symbol.InitialFrequency > 0 &&
parent.Grammar.GetMinimumExpressionDepth(symbol) <= maxDepth &&
parent.Grammar.GetMinimumExpressionLength(symbol) <= maxLength)
{
allowedSymbols.Add(symbol);
}
}
#endregion
#region check for semantic difference with a new random tree
if (allowedSymbols.Count > 0)
{
if (semanticTries <= maximumSemanticTries)
{
// do semantic mutation
#region calculate original json output
ISymbolicExpressionTreeNode statement = SemanticOperatorHelper.GetStatementNode(child, statementProductionNames);
var statementPos0 = symbolicExpressionTree.IterateNodesPrefix().ToList().IndexOf(statement);
if (String.IsNullOrEmpty(variableSettings))
{
variableSettings = SemanticOperatorHelper.SemanticToPythonVariableSettings(semantics.First(x => x.TreeNodePrefixPos == statementPos0).Before, problemData.Variables.GetVariableTypes());
}
var jsonOriginal = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
#endregion
var seedNode = GenerateAndInsertNewSubtree(random, parent, allowedSymbols, childIndex, maxLength, maxDepth);
#region calculate new json output
JObject jsonReplaced;
if (child == statement)
{
// child is executable, so is the new child
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(seedNode, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
else
{
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
if (JToken.EqualityComparer.Equals(jsonOriginal, jsonReplaced))
{
// semantically equivalent. undo mutation
parent.RemoveSubtree(childIndex);
parent.InsertSubtree(childIndex, child);
allowedSymbols.Clear();
}
else
{
Console.WriteLine("never happens?");
}
if (problemData.VariableSettings.Count == 0)
{
// reset variableSettings
variableSettings = String.Empty;
}
semanticTries++;
#endregion
}
else
{
// do random mutation
GenerateAndInsertNewSubtree(random, parent, allowedSymbols, childIndex, maxLength, maxDepth);
}
}
#endregion
tries++;
} while (tries < MAX_TRIES && allowedSymbols.Count == 0 && semanticTries <= maximumSemanticTries);
}
public override void ReplaceBranch(IRandom random, ISymbolicExpressionTree symbolicExpressionTree, ICFGPythonProblemData problemData, ItemArray <PythonStatementSemantic> semantics, PythonProcess pythonProcess, double timeout, int maxTreeLength, int maxTreeDepth, int maximumSemanticTries)
{
if (semantics == null || semantics.Length == 0)
{
ReplaceBranchManipulation.ReplaceRandomBranch(random, symbolicExpressionTree, maxTreeLength, maxTreeDepth);
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(NoSemantics);
MutationTypeParameter.ActualValue = new IntValue(RandomMutation);
return;
}
var statementProductionNames = SemanticOperatorHelper.GetSemanticProductionNames(symbolicExpressionTree.Root.Grammar);
var variables = problemData.Variables.GetVariableNames().ToList();
string variableSettings = problemData.VariableSettings.Count == 0 ? String.Empty : String.Join(Environment.NewLine, problemData.VariableSettings.Select(x => x.Value));
var allowedSymbols = new List <ISymbol>();
// repeat until a fitting parent and child are found (MAX_TRIES times)
int tries = 0;
int semanticTries = 0;
List <JObject> saveOriginalSemantics = null;
List <JObject> saveReplaceSemantics = null;
List <Tuple <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode, int> > possibleChildren = null; // Item1 = parent, Item2 = seedNode, Item3 = childIndex
if (UsesAdditionalSemanticMeasure())
{
saveOriginalSemantics = new List <JObject>(semanticTries);
saveReplaceSemantics = new List <JObject>(semanticTries);
possibleChildren = new List <Tuple <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode, int> >(semanticTries);
}
bool success = false;
do
{
#region find mutation point
#pragma warning disable 612, 618
ISymbolicExpressionTreeNode parent = symbolicExpressionTree.Root.IterateNodesPrefix().Skip(1).Where(n => n.SubtreeCount > 0).SelectRandom(random);
#pragma warning restore 612, 618
int childIndex = random.Next(parent.SubtreeCount);
var child = parent.GetSubtree(childIndex);
int maxLength = maxTreeLength - symbolicExpressionTree.Length + child.GetLength();
int maxDepth = maxTreeDepth - symbolicExpressionTree.Root.GetBranchLevel(child);
allowedSymbols.Clear();
foreach (var symbol in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, childIndex))
{
// check basic properties that the new symbol must have
if ((symbol.Name != child.Symbol.Name || symbol.MinimumArity > 0) &&
symbol.InitialFrequency > 0 &&
parent.Grammar.GetMinimumExpressionDepth(symbol) <= maxDepth &&
parent.Grammar.GetMinimumExpressionLength(symbol) <= maxLength)
{
allowedSymbols.Add(symbol);
}
}
#endregion
#region check for semantic difference with a new random tree
if (allowedSymbols.Count > 0)
{
if (semanticTries <= maximumSemanticTries)
{
// do semantic mutation
#region calculate original json output
ISymbolicExpressionTreeNode statement = SemanticOperatorHelper.GetStatementNode(child, statementProductionNames);
var statementPos0 = symbolicExpressionTree.IterateNodesPrefix().ToList().IndexOf(statement);
PythonStatementSemantic curSemantics = null;
if (String.IsNullOrEmpty(variableSettings))
{
curSemantics = semantics.First(x => x.TreeNodePrefixPos == statementPos0);
variableSettings = SemanticOperatorHelper.SemanticToPythonVariableSettings(curSemantics.Before, problemData.Variables.GetVariableTypes());
}
var jsonOriginal = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
// compare jsonOriginal to semantic after! Maybe avoid additional evaluation.
#endregion
var seedNode = GenerateAndInsertNewSubtree(random, parent, allowedSymbols, childIndex, maxLength, maxDepth);
#region calculate new json output
JObject jsonReplaced;
if (child == statement)
{
// child is executable, so is the new child
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(seedNode, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
else
{
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
var exception = jsonOriginal["exception"] != null || jsonReplaced["exception"] != null;
if (exception)
{
if (jsonOriginal["exception"] != null)
{
MutationExceptionsParameter.ActualValue.Add(new StringValue(jsonOriginal["exception"].ToString()));
}
if (jsonReplaced["exception"] != null)
{
MutationExceptionsParameter.ActualValue.Add(new StringValue(jsonReplaced["exception"].ToString()));
}
}
if (curSemantics != null && !exception)
{
jsonOriginal = PythonSemanticComparer.ReplaceNotExecutedCases(jsonOriginal, curSemantics.Before, curSemantics.ExecutedCases);
jsonReplaced = PythonSemanticComparer.ReplaceNotExecutedCases(jsonReplaced, curSemantics.Before, curSemantics.ExecutedCases);
jsonOriginal = PythonSemanticComparer.ProduceDifference(jsonOriginal, curSemantics.Before);
jsonReplaced = PythonSemanticComparer.ProduceDifference(jsonReplaced, curSemantics.Before);
}
if (!exception && SemanticMeasure(jsonOriginal, jsonReplaced))
{
success = true;
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(Different);
TypeSelectedForSimilarityParameter.ActualValue = new StringValue("First Semantic");
MutationTypeParameter.ActualValue = new IntValue(SemanticMutation);
}
else
{
// undo mutation
parent.RemoveSubtree(childIndex);
parent.InsertSubtree(childIndex, child);
allowedSymbols.Clear();
if (!exception && UsesAdditionalSemanticMeasure())
{
saveOriginalSemantics.Add(jsonOriginal);
saveReplaceSemantics.Add(jsonReplaced);
possibleChildren.Add(new Tuple <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode, int>(parent, seedNode, childIndex));
}
}
if (problemData.VariableSettings.Count == 0)
{
// reset variableSettings
variableSettings = String.Empty;
}
semanticTries++;
#endregion
#region try second semantic comparison
if (!success && semanticTries >= maximumSemanticTries && UsesAdditionalSemanticMeasure())
{
for (int index = 0; index < saveOriginalSemantics.Count; index++)
{
if (AdditionalSemanticMeasure(saveOriginalSemantics[index], saveReplaceSemantics[index]))
{
var mutation = possibleChildren[index];
mutation.Item1.RemoveSubtree(mutation.Item3);
mutation.Item1.InsertSubtree(mutation.Item3, mutation.Item2);
success = true;
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(Different);
TypeSelectedForSimilarityParameter.ActualValue = new StringValue("Second Semantic");
MutationTypeParameter.ActualValue = new IntValue(SemanticMutation);
break;
}
}
}
#endregion
}
else
{
// do random mutation
#region calculate original json output
ISymbolicExpressionTreeNode statement = SemanticOperatorHelper.GetStatementNode(child, statementProductionNames);
var statementPos0 = symbolicExpressionTree.IterateNodesPrefix().ToList().IndexOf(statement);
if (String.IsNullOrEmpty(variableSettings))
{
variableSettings = SemanticOperatorHelper.SemanticToPythonVariableSettings(semantics.First(x => x.TreeNodePrefixPos == statementPos0).Before, problemData.Variables.GetVariableTypes());
}
var jsonOriginal = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
#endregion
var seedNode = GenerateAndInsertNewSubtree(random, parent, allowedSymbols, childIndex, maxLength, maxDepth);
JObject jsonReplaced;
if (child == statement)
{
// child is executable, so is the new child
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(seedNode, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
else
{
jsonReplaced = SemanticOperatorHelper.EvaluateStatementNode(statement, pythonProcess, random, problemData, variables, variableSettings, timeout);
}
if (JToken.EqualityComparer.Equals(jsonOriginal, jsonReplaced))
{
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(Equvivalent);
}
else
{
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(Different);
}
TypeSelectedForSimilarityParameter.ActualValue = new StringValue("Random Crossover; Reached Max Semantic Tries");
MutationTypeParameter.ActualValue = new IntValue(RandomMutation);
success = true;
}
}
#endregion
tries++;
} while (tries < MAX_TRIES && !success);
NumberOfTriesParameter.ActualValue = new IntValue(semanticTries);
if (SemanticallyEquivalentMutationParameter.ActualValue == null)
{
SemanticallyEquivalentMutationParameter.ActualValue = new IntValue(NoMutation);
TypeSelectedForSimilarityParameter.ActualValue = new StringValue("No mutation");
MutationTypeParameter.ActualValue = new IntValue(NoMutation);
}
}
private static void ReplaceWithMinimalTree(IRandom random, ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode parent, int childIndex) {
// determine possible symbols that will lead to the smallest possible tree
var possibleSymbols = (from s in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, childIndex)
where s.InitialFrequency > 0.0
group s by parent.Grammar.GetMinimumExpressionLength(s) into g
orderby g.Key
select g).First().ToList();
var weights = possibleSymbols.Select(x => x.InitialFrequency).ToList();
#pragma warning disable 612, 618
var selectedSymbol = possibleSymbols.SelectRandom(weights, random);
#pragma warning restore 612, 618
var newTreeNode = selectedSymbol.CreateTreeNode();
if (newTreeNode.HasLocalParameters) newTreeNode.ResetLocalParameters(random);
parent.RemoveSubtree(childIndex);
parent.InsertSubtree(childIndex, newTreeNode);
var topLevelNode = newTreeNode as SymbolicExpressionTreeTopLevelNode;
if (topLevelNode != null)
topLevelNode.SetGrammar((ISymbolicExpressionTreeGrammar)root.Grammar.Clone());
for (int i = 0; i < newTreeNode.Grammar.GetMinimumSubtreeCount(newTreeNode.Symbol); i++) {
// insert a dummy sub-tree and add the pending extension to the list
var dummy = new SymbolicExpressionTreeNode();
newTreeNode.AddSubtree(dummy);
// replace the just inserted dummy by recursive application
ReplaceWithMinimalTree(random, root, newTreeNode, i);
}
}
private void SwitchNodeWithReplacementNode(ISymbolicExpressionTreeNode parent, int subTreeIndex) {
ISymbolicExpressionTreeNode subTree = parent.GetSubtree(subTreeIndex);
if (foldedNodes.ContainsKey(subTree)) {
parent.RemoveSubtree(subTreeIndex);
var replacementNode = foldedNodes[subTree];
parent.InsertSubtree(subTreeIndex, replacementNode);
// exchange key and value
foldedNodes.Remove(subTree);
foldedNodes.Add(replacementNode, subTree);
}
}
private static bool TryCreateFullTreeFromSeed(IRandom random, ISymbolicExpressionTreeNode root,
int targetLength, int maxDepth)
{
List <TreeExtensionPoint> extensionPoints = new List <TreeExtensionPoint>();
int currentLength = 0;
int actualArity = SampleArity(random, root, targetLength, maxDepth);
if (actualArity < 0)
{
return(false);
}
for (int i = 0; i < actualArity; i++)
{
// insert a dummy sub-tree and add the pending extension to the list
var dummy = new SymbolicExpressionTreeNode();
root.AddSubtree(dummy);
var x = new TreeExtensionPoint {
Parent = root, ChildIndex = i, ExtensionPointDepth = 0
};
FillExtensionLengths(x, maxDepth);
extensionPoints.Add(x);
}
//necessary to use long data type as the extension point length could be int.MaxValue
long minExtensionPointsLength = extensionPoints.Select(x => (long)x.MinimumExtensionLength).Sum();
long maxExtensionPointsLength = extensionPoints.Select(x => (long)x.MaximumExtensionLength).Sum();
// while there are pending extension points and we have not reached the limit of adding new extension points
while (extensionPoints.Count > 0 && minExtensionPointsLength + currentLength <= targetLength)
{
int randomIndex = random.Next(extensionPoints.Count);
TreeExtensionPoint nextExtension = extensionPoints[randomIndex];
extensionPoints.RemoveAt(randomIndex);
ISymbolicExpressionTreeNode parent = nextExtension.Parent;
int argumentIndex = nextExtension.ChildIndex;
int extensionDepth = nextExtension.ExtensionPointDepth;
if (parent.Grammar.GetMinimumExpressionDepth(parent.Symbol) > maxDepth - extensionDepth)
{
ReplaceWithMinimalTree(random, root, parent, argumentIndex);
int insertedTreeLength = parent.GetSubtree(argumentIndex).GetLength();
currentLength += insertedTreeLength;
minExtensionPointsLength -= insertedTreeLength;
maxExtensionPointsLength -= insertedTreeLength;
}
else
{
//remove currently chosen extension point from calculation
minExtensionPointsLength -= nextExtension.MinimumExtensionLength;
maxExtensionPointsLength -= nextExtension.MaximumExtensionLength;
var symbols = from s in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, argumentIndex)
where s.InitialFrequency > 0.0
where parent.Grammar.GetMinimumExpressionDepth(s) <= maxDepth - extensionDepth
where parent.Grammar.GetMinimumExpressionLength(s) <= targetLength - currentLength - minExtensionPointsLength
select s;
if (maxExtensionPointsLength < targetLength - currentLength)
{
symbols = from s in symbols
where parent.Grammar.GetMaximumExpressionLength(s, maxDepth - extensionDepth) >= targetLength - currentLength - maxExtensionPointsLength
select s;
}
var allowedSymbols = symbols.ToList();
if (allowedSymbols.Count == 0)
{
return(false);
}
var weights = allowedSymbols.Select(x => x.InitialFrequency).ToList();
#pragma warning disable 612, 618
var selectedSymbol = allowedSymbols.SelectRandom(weights, random);
#pragma warning restore 612, 618
ISymbolicExpressionTreeNode newTree = selectedSymbol.CreateTreeNode();
if (newTree.HasLocalParameters)
{
newTree.ResetLocalParameters(random);
}
parent.RemoveSubtree(argumentIndex);
parent.InsertSubtree(argumentIndex, newTree);
var topLevelNode = newTree as SymbolicExpressionTreeTopLevelNode;
if (topLevelNode != null)
{
topLevelNode.SetGrammar((ISymbolicExpressionTreeGrammar)root.Grammar.Clone());
}
currentLength++;
actualArity = SampleArity(random, newTree, targetLength - currentLength, maxDepth - extensionDepth);
if (actualArity < 0)
{
return(false);
}
for (int i = 0; i < actualArity; i++)
{
// insert a dummy sub-tree and add the pending extension to the list
var dummy = new SymbolicExpressionTreeNode();
newTree.AddSubtree(dummy);
var x = new TreeExtensionPoint {
Parent = newTree, ChildIndex = i, ExtensionPointDepth = extensionDepth + 1
};
FillExtensionLengths(x, maxDepth);
extensionPoints.Add(x);
maxExtensionPointsLength += x.MaximumExtensionLength;
minExtensionPointsLength += x.MinimumExtensionLength;
}
}
}
// fill all pending extension points
while (extensionPoints.Count > 0)
{
int randomIndex = random.Next(extensionPoints.Count);
TreeExtensionPoint nextExtension = extensionPoints[randomIndex];
extensionPoints.RemoveAt(randomIndex);
ISymbolicExpressionTreeNode parent = nextExtension.Parent;
int a = nextExtension.ChildIndex;
ReplaceWithMinimalTree(random, root, parent, a);
}
return(true);
}
private void SwitchNode(ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode oldBranch, ISymbolicExpressionTreeNode newBranch) {
for (int i = 0; i < root.SubtreeCount; i++) {
if (root.GetSubtree(i) == oldBranch) {
root.RemoveSubtree(i);
root.InsertSubtree(i, newBranch);
return;
}
}
}
