/// <summary>
/// Randomly returns a terminal node for the given <paramref name="parentNode"/>.
/// (A terminal has got a minimum and maximum arity of 0.)
/// </summary>
/// <param name="parentNode">parent node for which a child node is returned randomly</param>
/// <param name="grammar">grammar to determine the allowed child symbols for parentNode</param>
/// <param name="random">random number generator</param>
/// <returns>randomly chosen terminal node with arity 0 or null, if no terminal node exists</returns>
protected ISymbolicExpressionTreeNode GetRandomTerminalNode(ISymbolicExpressionTreeNode parentNode,
ISymbolicExpressionGrammar grammar,
IRandom random)
{
// 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();
// no terminal node exists for the given parent node
if (!possibleSymbolsList.Any())
{
return(null);
}
var newNode = possibleSymbolsList.SampleRandom(random).CreateTreeNode();
if (newNode.HasLocalParameters)
{
newNode.ResetLocalParameters(random);
}
return(newNode);
}
/// <summary>
/// Returns a randomly chosen child node for the given <paramref name="parentNode"/>.
/// </summary>
/// <param name="parentNode">parent node to find a child node randomly for</param>
/// <param name="genotype">integer vector, which should be mapped to a tree</param>
/// <param name="grammar">grammar used to define the allowed child symbols</param>
/// <param name="genotypeIndex">index in the integer vector; can be greater than vector length</param>
/// <param name="random">random number generator</param>
/// <returns>randomly chosen child node or null, if no child node exits</returns>
protected ISymbolicExpressionTreeNode GetNewChildNode(ISymbolicExpressionTreeNode parentNode,
IntegerVector genotype,
ISymbolicExpressionGrammar grammar,
int genotypeIndex,
IRandom random)
{
// 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();
// no child node exists for the given parent node
if (prodRuleCount < 1)
{
return(null);
}
// genotypeIndex % genotype.Length, if wrapping is allowed
int prodRuleIndex = genotype[genotypeIndex] % prodRuleCount;
var newNode = symbolList.ElementAt(prodRuleIndex).CreateTreeNode();
if (newNode.HasLocalParameters)
{
newNode.ResetLocalParameters(random);
}
return(newNode);
}
private void BuildAllowedChildSymbolsTree()
{
if (Symbol == null)
{
symbolicExpressionTreeChart.Tree = null;
return;
}
var tree = new SymbolicExpressionTree(new SymbolicExpressionTreeNode(Symbol));
if (Grammar.GetMaximumSubtreeCount(Symbol) > 0)
{
for (int i = 0; i < Grammar.GetMaximumSubtreeCount(Symbol); i++)
{
var node = new DummySymbol("Subtree " + i).CreateTreeNode();
var groupSymbols = grammar.GetAllowedChildSymbols(Symbol, i).OfType <GroupSymbol>().ToList();
foreach (var childSymbol in Grammar.GetAllowedChildSymbols(Symbol, i))
{
if (!groupSymbols.Any(g => g != childSymbol && g.Flatten().Contains(childSymbol)))
{
node.AddSubtree(new SymbolicExpressionTreeNode(childSymbol));
}
}
tree.Root.AddSubtree(node);
}
}
symbolicExpressionTreeChart.Tree = tree;
symbolicExpressionTreeChart.SuspendRepaint = true;
foreach (var subtreeNode in tree.Root.Subtrees)
{
foreach (var allowedChildNode in subtreeNode.Subtrees)
{
var visualLine = symbolicExpressionTreeChart.GetVisualSymbolicExpressionTreeNodeConnection(subtreeNode, allowedChildNode);
visualLine.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
}
}
for (int i = Grammar.GetMinimumSubtreeCount(symbol); i < Grammar.GetMaximumSubtreeCount(symbol); i++)
{
var subtreeNode = tree.Root.GetSubtree(i);
var visualTreeNode = symbolicExpressionTreeChart.GetVisualSymbolicExpressionTreeNode(subtreeNode);
visualTreeNode.TextColor = Color.Gray;
visualTreeNode.LineColor = Color.LightGray;
var visualLine = symbolicExpressionTreeChart.GetVisualSymbolicExpressionTreeNodeConnection(tree.Root, subtreeNode);
visualLine.LineColor = Color.LightGray;
foreach (var allowedChildNode in subtreeNode.Subtrees)
{
visualTreeNode = symbolicExpressionTreeChart.GetVisualSymbolicExpressionTreeNode(allowedChildNode);
visualTreeNode.TextColor = Color.Gray;
visualTreeNode.LineColor = Color.LightGray;
visualLine = symbolicExpressionTreeChart.GetVisualSymbolicExpressionTreeNodeConnection(subtreeNode, allowedChildNode);
visualLine.LineColor = Color.LightGray;
}
}
symbolicExpressionTreeChart.SuspendRepaint = false;
UpdateSelectedSymbolicExpressionTreeNodes();
}
/// <summary>
/// Randomly returns a terminal node for the given <paramref name="parentNode"/>.
/// (A terminal has got a minimum and maximum arity of 0.)
/// </summary>
/// <param name="parentNode">parent node for which a child node is returned randomly</param>
/// <param name="grammar">grammar to determine the allowed child symbols for parentNode</param>
/// <param name="random">random number generator</param>
/// <returns>randomly chosen terminal node with arity 0 or null, if no terminal node exists</returns>
protected ISymbolicExpressionTreeNode GetRandomTerminalNode(ISymbolicExpressionTreeNode parentNode,
ISymbolicExpressionGrammar grammar,
IRandom random) {
// 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();
// no terminal node exists for the given parent node
if (!possibleSymbolsList.Any()) return null;
var newNode = possibleSymbolsList.SampleRandom(random).CreateTreeNode();
if (newNode.HasLocalParameters) newNode.ResetLocalParameters(random);
return newNode;
}
public IEnumerable <ISymbol> GetAllowedChildSymbols(ISymbol parent)
{
return(grammar.GetAllowedChildSymbols(parent));
}
/// <summary>
/// Returns a randomly chosen child node for the given <paramref name="parentNode"/>.
/// </summary>
/// <param name="parentNode">parent node to find a child node randomly for</param>
/// <param name="genotype">integer vector, which should be mapped to a tree</param>
/// <param name="grammar">grammar used to define the allowed child symbols</param>
/// <param name="genotypeIndex">index in the integer vector; can be greater than vector length</param>
/// <param name="random">random number generator</param>
/// <returns>randomly chosen child node or null, if no child node exits</returns>
protected ISymbolicExpressionTreeNode GetNewChildNode(ISymbolicExpressionTreeNode parentNode,
IntegerVector genotype,
ISymbolicExpressionGrammar grammar,
int genotypeIndex,
IRandom random) {
// 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();
// no child node exists for the given parent node
if (prodRuleCount < 1) return null;
// genotypeIndex % genotype.Length, if wrapping is allowed
int prodRuleIndex = genotype[genotypeIndex] % prodRuleCount;
var newNode = symbolList.ElementAt(prodRuleIndex).CreateTreeNode();
if (newNode.HasLocalParameters) newNode.ResetLocalParameters(random);
return newNode;
}