public static Stack <GPTreeNode> GetNodeStack(string originalExpression)
{
if (string.IsNullOrWhiteSpace(originalExpression))
{
return(null);
}
var customGene = new FlexibleGPGene(FlexibleGPGene.AllFunctions.ToList(), 1);
//gets the reverse (polish notation) expression and the elements in the expression
var elements = originalExpression.Split(' ');
//creates stack of nodes for each element in the reverse expression
var nodeStack = new Stack <GPTreeNode>();
foreach (var element in elements)
{
if (!string.IsNullOrEmpty(element))
{
nodeStack.Push(IsZeroNode(element) ? ZeroNode : new GPTreeNode(customGene.CreateNew(element)));
}
}
return(nodeStack);
}
public static HashSet <IGPChromosome> GenerateAllCombinations(GPTreeNode node)
{
var combChromosomes = new HashSet <IGPChromosome>();
//tests end condition, ie no more children, add node itself
if ((node.Children == null) || (node.Children.Count == 0))
{
combChromosomes.Add(new GPExpressionChromosome(node.ToString()));
return(combChromosomes);
}
//add all combinations from each child
foreach (var child in node.Children)
{
combChromosomes.UnionWith(GenerateAllCombinations(child));
}
//for one argument functions, gets children
var children0 = GetAllChildren(node.Children[0]);
//creates combinations for all children
foreach (var child0 in children0)
{
var newNode = (GPTreeNode)node.Clone();
newNode.Children[0] = child0;
combChromosomes.Add(new GPExpressionChromosome(newNode.ToString()));
}
//for two argument functions
if (node.Children.Count < 2)
{
return(combChromosomes);
}
//gets children from both sides
var children1 = GetAllChildren(node.Children[1]);
//creates combinations between the different children
foreach (var child0 in children0)
{
foreach (var child1 in children1)
{
var newNode = (GPTreeNode)node.Clone();
newNode.Children[0] = child0;
newNode.Children[1] = child1;
combChromosomes.Add(new GPExpressionChromosome(newNode.ToString()));
}
}
//if function is subtraction
if (!node.Gene.ToString().Equals(FlexibleGPGene.GetFunctionTypeString(FunctionType.Subtract)))
{
return(combChromosomes);
}
//consider right side negative by adding "0 - 'childNode'"
foreach (var child1 in children1)
{
var newNode = (GPTreeNode)node.Clone();
newNode.Children[0] = ZeroNode;
newNode.Children[1] = child1;
combChromosomes.Add(new GPExpressionChromosome(newNode.ToString()));
}
return(combChromosomes);
}
