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NQueensSearchDemo.java
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NQueensSearchDemo.java
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package aima.gui.fx.applications.search;
import aima.core.environment.nqueens.NQueensBoard;
import aima.core.environment.nqueens.NQueensBoard.Config;
import aima.core.environment.nqueens.NQueensFunctions;
import aima.core.environment.nqueens.NQueensGenAlgoUtil;
import aima.core.environment.nqueens.QueenAction;
import aima.core.search.framework.Metrics;
import aima.core.search.framework.SearchForActions;
import aima.core.search.framework.problem.GeneralProblem;
import aima.core.search.framework.problem.Problem;
import aima.core.search.framework.qsearch.TreeSearch;
import aima.core.search.local.*;
import aima.core.search.uninformed.DepthFirstSearch;
import java.util.*;
/**
* Command line demo which demonstrates how different search algorithms
* solve the n-queens problem.
*
* @author Ruediger Lunde
*/
public class NQueensSearchDemo {
private int boardSize = 8;
private int populationSize = 10;
private double mutationProbability = 0.2;
public int k = 30;
private double lambda = 2.0 / 100;
private int maxIterations = 500;
private static Random random = new Random();
private GeneticAlgorithm<Integer> genAlgo;
private SearchForActions<NQueensBoard, QueenAction> search;
private NQueensBoard board;
private List<ProgressTracker> progressTracers = new ArrayList<>();
public static void main(String[] args) {
NQueensSearchDemo demo = new NQueensSearchDemo();
// prog.setBoardSize(32);
demo.addProgressTracker(demo::printProgress);
System.out.println("NQueens depth-first search experiment (boardSize=" + demo.boardSize + ") -->");
demo.initExperiment(Config.EMPTY);
demo.startExperiment(new DepthFirstSearch<>(new TreeSearch<>()));
demo.printResult();
System.out.println("NQueens hill climbing search experiment (boardSize=" + demo.boardSize + ") -->");
demo.initExperiment(Config.QUEENS_IN_FIRST_ROW);
demo.startHillClimbingExperiment();
demo.printResult();
System.out.println("NQueens simulated annealing experiment (boardSize=" + demo.boardSize + ", maxIterations="
+ demo.maxIterations + ") -->");
demo.initExperiment(Config.QUEENS_IN_FIRST_ROW);
demo.startSimulatedAnnealingExperiment();
demo.printResult();
System.out.println("NQueens genetic algorithm experiment (boardSize=" + demo.boardSize + ", popSize="
+ demo.populationSize + ", mutProb=" + demo.mutationProbability + ") -->");
demo.initExperiment(Config.EMPTY);
demo.startGenAlgoExperiment(false);
demo.printResult();
}
public void setBoardSize(int size) {
boardSize = size;
board = new NQueensBoard(boardSize);
}
public void addProgressTracker(ProgressTracker tracer) {
progressTracers.add(tracer);
}
public void initExperiment(Config config) {
board = new NQueensBoard(boardSize, config);
genAlgo = null;
search = null;
}
public void startExperiment(SearchForActions<NQueensBoard, QueenAction> search) {
search.addNodeListener(n -> notifyProgressTrackers(n.getState(), search.getMetrics()));
Problem<NQueensBoard, QueenAction> problem;
if (board.getNumberOfQueensOnBoard() == 0)
problem = new GeneralProblem<>(board, NQueensFunctions::getIFActions,
NQueensFunctions::getResult, NQueensFunctions::testGoal);
else
problem = new GeneralProblem<>(board, NQueensFunctions::getCSFActions,
NQueensFunctions::getResult, NQueensFunctions::testGoal);
Optional<List<QueenAction>> actions = search.findActions(problem);
if (actions.isPresent())
for (QueenAction action : actions.get())
board = NQueensFunctions.getResult(board, action);
notifyProgressTrackers(board, search.getMetrics());
}
public void startHillClimbingExperiment() {
// board = new NQueensBoard(boardSize, Config.QUEEN_IN_EVERY_COL);
Problem<NQueensBoard, QueenAction> problem = new GeneralProblem<>(board, NQueensFunctions::getCSFActions,
NQueensFunctions::getResult, NQueensFunctions::testGoal);
search = new HillClimbingSearch<>(NQueensFunctions::getNumberOfAttackingPairs);
search.addNodeListener(n -> notifyProgressTrackers(n.getState(), search.getMetrics()));
search.findActions(problem);
board = (NQueensBoard) ((HillClimbingSearch) search).getLastState();
notifyProgressTrackers(board, search.getMetrics());
}
public void startSimulatedAnnealingExperiment() {
Problem<NQueensBoard, QueenAction> problem = new GeneralProblem<>(board, NQueensFunctions::getCSFActions,
NQueensFunctions::getResult, NQueensFunctions::testGoal);
Scheduler scheduler = new Scheduler(k, lambda, maxIterations);
search = new SimulatedAnnealingSearch<>(NQueensFunctions::getNumberOfAttackingPairs, scheduler);
search.addNodeListener(n -> notifyProgressTrackers(n.getState(), search.getMetrics()));
search.findActions(problem);
board = (NQueensBoard) ((SimulatedAnnealingSearch) search).getLastState();
notifyProgressTrackers(board, search.getMetrics());
}
public void startGenAlgoExperiment(boolean randomConfig) {
Collection<Integer> alphabet = NQueensGenAlgoUtil.getFiniteAlphabetForBoardOfSize(boardSize);
FitnessFunction<Integer> fitnessFn = NQueensGenAlgoUtil.getFitnessFunction();
genAlgo = new GeneticAlgorithm<Integer>(boardSize, alphabet, mutationProbability, random) {
protected void updateMetrics(Collection<Individual<Integer>> pop, int itCount, long time) {
super.updateMetrics(pop, itCount, time);
double avg = 0.0;
double max = Double.NEGATIVE_INFINITY;
for (Individual<Integer> ind : pop) {
double fval = fitnessFn.apply(ind);
avg += fval;
max = Math.max(max, fval);
}
avg /= pop.size();
metrics.set("fitMax", max);
metrics.set("fitAvg", avg);
}
};
genAlgo.addProgressTracer((it, pop) -> notifyProgressTrackers(pop, fitnessFn));
List<Individual<Integer>> population = new ArrayList<>();
List<Integer> rep = new ArrayList<>();
for (int i = 0; i < boardSize; i++)
rep.add(0);
for (int i = 0; i < populationSize; i++)
if (randomConfig)
population.add(NQueensGenAlgoUtil.generateRandomIndividual(boardSize));
else
population.add(new Individual<>(rep));
Individual<Integer> result = genAlgo.geneticAlgorithm(population, fitnessFn, maxIterations);
board = NQueensGenAlgoUtil.getBoardForIndividual(result);
}
public NQueensBoard getBoard() {
return board;
}
private void printProgress(NQueensBoard board, Metrics metrics) {
System.out.println(board.getNumberOfAttackingPairs() + " attacking pairs " + metrics);
}
private void printResult() {
if (board != null) {
System.out.println("Final State:\n" + board);
System.out.println("Attacking pairs: " + board.getNumberOfAttackingPairs());
}
if (genAlgo != null)
System.out.println("Metrics: " + genAlgo.getMetrics());
if (search != null)
System.out.println("Metrics: " + search.getMetrics());
System.out.println("Experiment finished.\n");
}
private void notifyProgressTrackers(Collection<Individual<Integer>> population, FitnessFunction<Integer> fitnessFn) {
Individual<Integer> best = genAlgo.retrieveBestIndividual(population, fitnessFn);
notifyProgressTrackers(NQueensGenAlgoUtil.getBoardForIndividual(best), genAlgo.getMetrics());
}
private void notifyProgressTrackers(NQueensBoard board, Metrics metrics) {
for (ProgressTracker tracker : progressTracers)
tracker.trackProgress(board, metrics);
}
public interface ProgressTracker {
void trackProgress(NQueensBoard board, Metrics metrics);
}
}