public void Mutate(GPNode root, int index1, int maxLevels)
{
//We dont want to crossover root
if (index1 == 1)
{
throw new Exception("Wrong index number for Mutate operation!");
}
//start counter from 0
int count = 0;
//Collection holds tree nodes
Queue <Tuple <int, GPNode> > dataTree = new Queue <Tuple <int, GPNode> >();
//current node
Tuple <int, GPNode> tuplenode = null;
//Add tail recursion
dataTree.Enqueue(new Tuple <int, GPNode>(0, root));
while (dataTree.Count > 0)
{
//get next node
tuplenode = dataTree.Dequeue();
//count node
count++;
//perform mutation
if (count == index1)
{
int level = maxLevels - tuplenode.Item1;
if (level < 0)
{
throw new Exception("Level is not a correct number!");
}
int rnd = Globals.radn.Next(level + 1);
if (level <= 1 || rnd == 0)
{
tuplenode.Item2.value = Globals.GenerateNodeValue(false);
GPNode.DestroyNodes(tuplenode.Item2.children);
tuplenode.Item2.children = null;
}
else
{
var node = GenerateTreeStructure(rnd);
tuplenode.Item2.value = node.value;
tuplenode.Item2.children = node.children;
}
break;
}
if (tuplenode.Item2.children != null)
{
for (int i = tuplenode.Item2.children.Length - 1; i >= 0; i--)
{
dataTree.Enqueue(new Tuple <int, GPNode>(tuplenode.Item1 + 1, tuplenode.Item2.children[i]));
}
}
}
}
