internal void Mutate()
{
// pick any node but the root (since that would be a replacement of the entire tree, not a mutation)
NodeBaseType <T, S> randomNode = null;
do
{
randomNode = SelectRandomNode();
} while (randomNode == Root);
// build a random subtree
bool buildFullTrees = Randomizer.GetFloatFromZeroToOne() < 0.5F;
int depth = Randomizer.IntBetween(TreeMinDepth, TreeMaxDepth);
var newSubtree = AddRandomNode(null, depth, buildFullTrees);
// replace the randomly selected node with the new random one
var parent = (FunctionNode <T, S>)randomNode.Parent;
newSubtree.Parent = parent;
// find the link from the parent to the old child, and replace it
for (int i = 0; i < parent.Children.Count; i++)
{
if (parent.Children[i] == randomNode)
{
parent.Children[i] = newSubtree;
break;
}
}
}
public void CreateRandom()
{
// ramped half-and-half approach:
// do grow or full approach, evenly split
// full: choose function nodes for all levels except the maximum, which is always terminal
// grow: randomly choose function or terminal, except for max depth which is always terminal
bool buildFullTrees = Randomizer.GetFloatFromZeroToOne() < 0.5;
int depth = Randomizer.IntBetween(TreeMinDepth, TreeMaxDepth);
Root = AddRandomNode(null, depth, buildFullTrees);
}
