TreeMutShrink.cpp

#include "../ECF_base.h"
#include "Tree.h"
#include "TreeMutShrink.h"
#include <stdio.h>
 
 
namespace Tree
{
 
void TreeMutShrink::registerParameters(StateP state)
{
    myGenotype_->registerParameter(state, "mut.shrink", (voidP) new double(0), ECF::DOUBLE);
}
 
 
bool TreeMutShrink::initialize(StateP state)
{
    voidP sptr = myGenotype_->getParameterValue(state, "mut.shrink");
    probability_ = *((double*)sptr.get());
    return true;
}
 
 
bool TreeMutShrink::mutate(GenotypeP gene)
{
    Tree* tree = (Tree*) (gene.get());
 
    // try to select random node in tree which is not a terminal
    // (it is silly to shrink just a terminal :))
    uint chosenNode;
    uint chosenNodeSubtreeSize;
    uint tries = 0;
    do {
        chosenNode = state_->getRandomizer()->getRandomInteger((int) tree->size());
        chosenNodeSubtreeSize = tree->at(chosenNode)->size_;
        tries++;
    } while(chosenNodeSubtreeSize == 1 && tries < 4);
 
    if(chosenNodeSubtreeSize == 1) {
        ECF_LOG(state_, 5, "TreeMutShrink not successful.");
        return false;
    }
 
    // first of all, make a copy and clear the original
    Tree* copyTree = tree->copy();
    tree->clear();
 
    std::stringstream log;
    log << "TreeMutShrink successful (";
 
    uint i = 0;
 
    // copy all nodes before chosen subtree to original
    for( ; i < chosenNode; i++) {
        NodeP node = static_cast<NodeP> (new Node(copyTree->at(i)->primitive_));
        tree->addNode(node);
    }
 
    log << "shrinkedSubtree = ";
    for( ; i < chosenNode + chosenNodeSubtreeSize; i++) {
        // these nodes are skipped because they are elements of the chosen subtree
        log << copyTree->at(i)->primitive_->getName() << " ";
    }
 
    // chosen subtree is shrinked to a random terminal
    Node* node = new Node;
    node->setPrimitive(copyTree->primitiveSet_->getRandomTerminal());
    tree->addNode(node);
    log << ", shrinkedTo = " << node->primitive_->getName() << ")";
 
    // copy all nodes after chosen subtree to original
    for( ; i < copyTree->size(); i++) {
        NodeP node = static_cast<NodeP> (new Node(copyTree->at(i)->primitive_));
        tree->addNode(node);
    }
 
    tree->update();
    delete copyTree;
 
    ECF_LOG(state_, 5, log.str());
 
    return true;
}
 
}