ControllerPtr PopulationControlArchitecture::getNextCandidate() { currentTime++; ControllerPtr candidate; // if there is no full list of active solutions yet, generate a new candidate randomly if (activeSolutions.size() < mu) { candidate = this->createRandomGenome(); if (debug) { cout << "Generated " << candidate->ToString() << endl; } } // get news from the population, spreading the active solution population->update(currentTime); // if there is a full list of active solutions, mutate an existing solution or re-evaluate an active to create a new candidate if (activeSolutions.size() == mu) { // decide whether to re-evaluate or mutate a controller if (Rand::randouble() < reEvaluationRate) { // re-evaluate // pick one of the active solutions for re-evaluation candidate = activeSolutions[Rand::randint(0, activeSolutions.size())]; if (debug) { cout << "Selected re-evaluation of " << candidate->ToShortString() << endl; } } else { // mutate existing // parent selection: random from the population ControllerPtr parentA = selectParentByBinaryTournament(ControllerPtr()); if (debug) { cout << "Selected first parent: " << parentA->ToShortString() << endl; } // crossover or clone; crossover only if there is a second active solution in the hivemind if (population->getActiveCount() > 1 && Rand::randouble() < crossoverRate) { if (debug) { cout << "Selecting second parent, from a choice of " << population->getActiveCount() << endl; } // crossover // select a second parent, excluding the first from the selection vector<ControllerPtr> *parents = new vector<ControllerPtr>(); parents->push_back(parentA); while (parents->size()<(unsigned) numberOfParents) { if (debug) { cout << parents->size() << endl; } ControllerPtr tmpC = selectParentsByBinaryTournament(parents); parents->push_back(tmpC); } // create a candidate from crossover between the parents candidate = parentA->crossOverWithMP(parents); if (debug) { cout << " Created " << candidate->ToShortString() << " from crossover between " << parents->at(0)->ToShortString(); for (uint i = 1; i < parents->size(); i++) cout << " and " << parents->at(i)->ToShortString(); cout << endl; } parents->clear(); delete parents; } else { // clone candidate = parentA->Clone(); if (debug) { cout << "Spawned " << candidate->ToShortString() << " from " << parentA->ToShortString() << endl; } } // mutation if (Rand::randouble() < mutationRate) { //cout << "Before mutation: " << candidate->ToString() << endl; candidate->mutate(); //cout << "After mutation: " << candidate->ToString() << endl; if (debug) { cout << "Mutated " << candidate->ToShortString() << endl; } } } } return candidate; }