public static void main(String[] args) {
Properties properties = new Properties();
properties.setProperty("populationSize", "10");
Problem problem = new OneMax(100);
Algorithm algorithm =
AlgorithmFactory.getInstance().getAlgorithm("NSGAII", properties, problem);
while (!algorithm.isTerminated()) {
algorithm.step();
NondominatedPopulation population = algorithm.getResult();
if (population.get(0).getObjective(0) == 0) {
// if all bits are 1
System.out.println(
"Found optimal solution after " + algorithm.getNumberOfEvaluations() + " evaluations!");
break;
}
}
}
/**
* Solves this TSPLIB instance while displaying a GUI showing the optimization progress.
*
* @param instance the TSPLIB instance to solve
*/
public static void solve(TSPInstance instance) {
TSPPanel panel = new TSPPanel(instance);
panel.setAutoRepaint(false);
// create other components on the display
StringBuilder progress = new StringBuilder();
JTextArea progressText = new JTextArea();
JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
splitPane.setTopComponent(panel);
splitPane.setBottomComponent(new JScrollPane(progressText));
splitPane.setDividerLocation(300);
splitPane.setResizeWeight(1.0);
// display the panel on a window
JFrame frame = new JFrame(instance.getName());
frame.getContentPane().setLayout(new BorderLayout());
frame.getContentPane().add(splitPane, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setSize(500, 400);
frame.setLocationRelativeTo(null);
frame.setIconImages(Settings.getIconImages());
frame.setVisible(true);
// create the optimization problem and evolutionary algorithm
Problem problem = new TSPProblem(instance);
Properties properties = new Properties();
properties.setProperty("swap.rate", "0.7");
properties.setProperty("insertion.rate", "0.9");
properties.setProperty("pmx.rate", "0.4");
Algorithm algorithm =
AlgorithmFactory.getInstance().getAlgorithm("NSGAII", properties, problem);
int iteration = 0;
// now run the evolutionary algorithm
while (frame.isVisible()) {
algorithm.step();
iteration++;
// clear existing tours in display
panel.clearTours();
// display population with light gray lines
if (algorithm instanceof EvolutionaryAlgorithm) {
EvolutionaryAlgorithm ea = (EvolutionaryAlgorithm) algorithm;
for (Solution solution : ea.getPopulation()) {
panel.displayTour(toTour(solution), lightGray);
}
}
// display current optimal solutions with red line
Tour best = toTour(algorithm.getResult().get(0));
panel.displayTour(best, Color.RED, new BasicStroke(2.0f));
progress.insert(0, "Iteration " + iteration + ": " + best.distance(instance) + "\n");
progressText.setText(progress.toString());
// repaint the TSP display
panel.repaint();
}
}
