private void Mutate(MathExpressionTree expression)
{
MathExpressionNode randomNode = expression.GetRandomNode();
randomNode.SubstiteValue(randomNode.IsLeaf ?
stohasticGenerator.GetRandomOperand()
: stohasticGenerator.GetRandomOperator(randomNode.LeftChild, randomNode.RightChild));
}
private void Crossover(MathExpressionTree first, MathExpressionTree second)
{
MathExpressionNode crossoverPointOfFirst = first.GetRandomSubtree();
MathExpressionNode crossoverPointOfSecond = second.GetRandomSubtree();
MathExpressionNode firstParent = crossoverPointOfFirst.Parent;
MathExpressionNode secondParent = crossoverPointOfSecond.Parent;
if (firstParent != null)
{
if (firstParent.LeftChild.Id == crossoverPointOfFirst.Id)
{
firstParent.LeftChild = crossoverPointOfSecond;
}
else
{
firstParent.RightChild = crossoverPointOfSecond;
}
}
else
{
first.Root = crossoverPointOfSecond;
}
if (secondParent != null)
{
if (secondParent.LeftChild.Id == crossoverPointOfSecond.Id)
{
secondParent.LeftChild = crossoverPointOfFirst;
}
else
{
secondParent.RightChild = crossoverPointOfFirst;
}
}
else
{
second.Root = crossoverPointOfFirst;
}
crossoverPointOfFirst.Parent = secondParent;
crossoverPointOfSecond.Parent = firstParent;
}
public MathExpressionTree GenerateIndividual()
{
MathExpressionTree validExpression;
do
{
int operandsCount = stohasticGenerator.OperandsCount();
List <MathExpressionNode> operatorsAndOperands = Enumerable.Range(0, 2 * operandsCount - 1)
.Select(x => x % 2 == 0 ? stohasticGenerator.GetRandomOperand() : stohasticGenerator.GetRandomOperator())
.ToList();
MathExpressionNode root = operatorsAndOperands.Where(x => !x.IsLeaf)
.OrderBy(x => Guid.NewGuid())
.First();
MathExpressionNode getGenome(List <MathExpressionNode> elements, MathExpressionNode parent, MathExpressionNode rootNode = null)
{
if (elements.Count == 0)
{
return(null);
}
MathExpressionNode currentNode = (rootNode ?? elements.FirstOrDefault(x => !x.IsLeaf)) ?? elements.First();
currentNode.Parent = parent;
if (!currentNode.IsLeaf)
{
int currentNodeIndex = elements.IndexOf(currentNode);
currentNode.LeftChild = getGenome(elements.Take(currentNodeIndex).ToList(), currentNode);
currentNode.RightChild = getGenome(elements.Skip(currentNodeIndex + 1).ToList(), currentNode);
}
return(currentNode);
}
validExpression = new MathExpressionTree(getGenome(operatorsAndOperands, null, root));
} while (!validExpression.IsValidExpression());
return(validExpression);
}
public Operator GetRandomOperator(MathExpressionNode firstOperand, MathExpressionNode secondOperand)
=> new Operator((Operation)randomGenerator.Next(max: operationCount))
{
LeftChild = firstOperand,
RightChild = secondOperand
};
