private void ResetCachedValues()
{
length = 0; depth = 0;
SymbolicExpressionTreeNode parentNode = parent as SymbolicExpressionTreeNode;
if (parentNode != null)
{
parentNode.ResetCachedValues();
}
}
protected SymbolicExpressionTreeNode(SymbolicExpressionTreeNode original, Cloner cloner)
: base(original, cloner) {
symbol = original.symbol; // symbols are reused
length = original.length;
depth = original.depth;
if (original.subtrees != null) {
subtrees = new List<ISymbolicExpressionTreeNode>(original.subtrees.Count);
foreach (var subtree in original.subtrees) {
var clonedSubtree = cloner.Clone(subtree);
subtrees.Add(clonedSubtree);
clonedSubtree.Parent = this;
}
}
}
protected SymbolicExpressionTreeNode(SymbolicExpressionTreeNode original, Cloner cloner)
: base(original, cloner)
{
symbol = original.symbol; // symbols are reused
length = original.length;
depth = original.depth;
if (original.subtrees != null)
{
subtrees = new List <ISymbolicExpressionTreeNode>(original.subtrees.Count);
foreach (var subtree in original.subtrees)
{
var clonedSubtree = cloner.Clone(subtree);
subtrees.Add(clonedSubtree);
clonedSubtree.Parent = this;
}
}
}
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);
}
}
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 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 ISymbolicExpressionTreeNode CreateNodeFromWeight(ISymbolicExpressionTreeNode transformationTree, VariableTreeNode variableNode) {
var multiplicationNode = new SymbolicExpressionTreeNode(new Multiplication());
multiplicationNode.AddSubtree(new ConstantTreeNode(new Constant()) { Value = variableNode.Weight });
multiplicationNode.AddSubtree(transformationTree);
return multiplicationNode;
}
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);
}
