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package jeco.core.problems;
import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.logging.Logger;
import javax.xml.parsers.DocumentBuilderFactory;
import jeco.core.problem.Problem;
import jeco.core.problem.Solution;
import jeco.core.problem.Solutions;
import jeco.core.problem.Variable;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
/**
* TSP.java
*
* @author José L. Risco-Martín
* @version 1.0
*/
/**
* Class representing a TSP (Traveling Salesman Problem) problem.
*/
public class TSP extends Problem> {
private static Logger logger = Logger.getLogger(TSP.class.getName());
protected String xmlFilePath = null;
public int numberOfCities;
public double[][] distanceMatrix;
public ArrayList cityNames;
/**
* Creates a new TSP problem instance. It accepts data files from TSPLIB
* @param xmlFilePath The file containing the definition of the problem
*/
public TSP(String xmlFilePath) {
super(1, 1);
this.xmlFilePath = xmlFilePath;
try {
readProblem(xmlFilePath);
} catch (Exception ee) {
ee.printStackTrace();
}
} // TSP
public void evaluate(Solutions> solutions) {
for(Solution> solution : solutions)
evaluate(solution);
}
/**
* Evaluates a solution
* @param solution The solution to evaluate
*/
public void evaluate(Solution> solution) {
double fitness;
fitness = 0.0;
for (int i = 0; i < (numberOfCities - 1); i++) {
int x;
int y;
x = solution.getVariables().get(i).getValue();
y = solution.getVariables().get(i + 1).getValue();
fitness += distanceMatrix[x][y];
} // for
int firstCity;
int lastCity;
firstCity = solution.getVariables().get(0).getValue();
lastCity = solution.getVariables().get(numberOfCities - 1).getValue();
fitness += distanceMatrix[firstCity][lastCity];
solution.getObjectives().set(0, fitness);
} // evaluate
public void readProblem(String xmlFilePath) throws Exception {
/**
*
*
*/
Document xmlTspModel = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File(xmlFilePath));
Element xmlTsp = (Element) xmlTspModel.getElementsByTagName("tsp").item(0);
HashSet cityNamesAsSet = new HashSet();
NodeList xmlDistances = xmlTsp.getElementsByTagName("distance");
for (int i = 0; i < xmlDistances.getLength(); ++i) {
Element xmlDistance = (Element) xmlDistances.item(i);
cityNamesAsSet.add(xmlDistance.getAttribute("from"));
cityNamesAsSet.add(xmlDistance.getAttribute("to"));
}
numberOfCities = cityNamesAsSet.size();
distanceMatrix = new double[numberOfCities][numberOfCities];
cityNames = new ArrayList();
int counter = 0;
HashMap cityIndexes = new HashMap();
for (String cityName : cityNamesAsSet) {
cityIndexes.put(cityName, counter++);
cityNames.add(cityName);
}
for (int i = 0; i < xmlDistances.getLength(); ++i) {
Element xmlDistance = (Element) xmlDistances.item(i);
String cityFrom = xmlDistance.getAttribute("from");
Integer indexFrom = cityIndexes.get(cityFrom);
String cityTo = xmlDistance.getAttribute("to");
Integer indexTo = cityIndexes.get(cityTo);
Double distance = Double.valueOf(xmlDistance.getAttribute("distance"));
distanceMatrix[indexFrom][indexTo] = distance;
}
} // readProblem
public Solutions> newRandomSetOfSolutions(int size) {
logger.severe("Method not implemented");
return null;
// TODO: Finish this method.
}
public TSP clone() {
TSP clone = new TSP(this.xmlFilePath);
for(int i=0; i