public override int Produce(
int min,
int max,
int subpop,
IList <Individual> inds,
IEvolutionState state,
int thread,
IDictionary <string, object> misc)
{
int start = inds.Count;
// grab individuals from our source and stick 'em right into inds.
// we'll modify them from there
var n = Sources[0].Produce(min, max, subpop, inds, state, thread, misc);
// should we bother?
if (!state.Random[thread].NextBoolean(Likelihood))
{
return(n);
}
var initializer = ((GPInitializer)state.Initializer);
// now let's mutate 'em
for (var q = start; q < n + start; q++)
{
var i = (GPIndividual)inds[q];
if (Tree != TREE_UNFIXED && (Tree < 0 || Tree >= i.Trees.Length))
{
// uh oh
state.Output.Fatal("GP Mutation Pipeline attempted to fix Tree.0 to a value which was out of bounds"
+ " of the array of the individual's Trees. Check the pipeline's fixed Tree values"
+ " -- they may be negative or greater than the number of Trees in an individual");
}
int t;
// pick random Tree
if (Tree == TREE_UNFIXED)
{
if (i.Trees.Length > 1)
{
t = state.Random[thread].NextInt(i.Trees.Length);
}
else
{
t = 0;
}
}
else
{
t = Tree;
}
// validity result...
var res = false;
// prepare the NodeSelector
NodeSelect.Reset();
// pick a node
GPNode p1 = null; // the node we pick
GPNode p2 = null;
for (var x = 0; x < NumTries; x++)
{
// pick a node in individual 1
p1 = NodeSelect.PickNode(state, subpop, thread, i, i.Trees[t]);
// generate a Tree swap-compatible with p1's position
var size = GPNodeBuilder.NOSIZEGIVEN;
if (EqualSize)
{
size = p1.NumNodes(GPNode.NODESEARCH_ALL);
}
p2 = Builder.NewRootedTree(state, p1.ParentType(initializer), thread, p1.Parent,
i.Trees[t].Constraints(initializer).FunctionSet, p1.ArgPosition, size);
// check for depth and swap-compatibility limits
res = VerifyPoints(p2, p1); // p2 can fit in p1's spot -- the order is important!
// did we get something that had both nodes verified?
if (res)
{
break;
}
}
if (res)
// we're in business
{
p2.Parent = p1.Parent;
p2.ArgPosition = p1.ArgPosition;
if (p2.Parent is GPNode)
{
((GPNode)p2.Parent).Children[p2.ArgPosition] = p2;
}
else
{
((GPTree)p2.Parent).Child = p2;
}
i.Evaluated = false; // we've modified it
}
// add the new individual, replacing its previous source
inds[q] = i;
}
return(n);
}
