protected void addRankedSolutionsToPopulation(Ranking ranking, int rank) throws JMetalException {
SolutionSet front;
front = ranking.getSubfront(rank);
for (int i = 0; i < front.size(); i++) {
population.add(front.get(i));
}
}
protected void addLastRankedSolutions(Ranking ranking, int rank) throws JMetalException {
SolutionSet currentRankedFront = ranking.getSubfront(rank);
currentRankedFront.sort(new CrowdingComparator());
int i = 0;
while (population.size() < populationSize) {
population.add(currentRankedFront.get(i));
i++;
}
}
protected void createInitialPopulation() throws ClassNotFoundException, JMetalException {
population = new SolutionSet(populationSize);
Solution newSolution;
for (int i = 0; i < populationSize; i++) {
newSolution = new Solution(problem);
population.add(newSolution);
}
}
/** Updates the reference point */
private void updateReferencePoint(SolutionSet solutionSet) {
double[] maxObjectives = new double[numberOfObjectives];
for (int i = 0; i < numberOfObjectives; i++) {
maxObjectives[i] = 0;
}
for (int i = 0; i < solutionSet.size(); i++) {
for (int j = 0; j < numberOfObjectives; j++) {
if (maxObjectives[j] < solutionSet.get(i).getObjective(j)) {
maxObjectives[j] = solutionSet.get(i).getObjective(j);
}
}
}
for (int i = 0; i < referencePoint.getNumberOfObjectives(); i++) {
referencePoint.setObjective(i, maxObjectives[i] + offset);
}
}
/** Execute() method */
public Object execute(Object object) throws JMetalException {
if (null == object) {
throw new JMetalException("Null parameter");
} else if (!(object instanceof Solution)) {
throw new JMetalException("Invalid parameter class");
}
int i = 0;
int best = 0;
evaluations = 0;
Solution solution = (Solution) object;
int rounds = improvementRounds;
if (rounds <= 0) {
return new Solution(solution);
}
do {
i++;
Solution mutatedSolution = new Solution(solution);
mutationOperator.execute(mutatedSolution);
// Evaluate the getNumberOfConstraints
if (problem.getNumberOfConstraints() > 0) {
problem.evaluateConstraints(mutatedSolution);
best = constraintComparator.compare(mutatedSolution, solution);
if (best == 0) {
// none of then is better that the other one
problem.evaluate(mutatedSolution);
evaluations++;
best = dominanceComparator.compare(mutatedSolution, solution);
} else if (best == -1) {
// mutatedSolution is best
problem.evaluate(mutatedSolution);
evaluations++;
}
} else {
problem.evaluate(mutatedSolution);
evaluations++;
best = dominanceComparator.compare(mutatedSolution, solution);
}
if (best == -1) {
// mutated is best
solution = mutatedSolution;
} else if (best == 1) {
// original is best
} else {
// mutatedSolution and original are non-dominated
if (archive != null) {
archive.add(mutatedSolution);
}
}
} while (i < rounds);
return new Solution(solution);
}
public double computeHypervolume(SolutionSet solutionSet) {
double hv;
if (solutionSet.size() == 0) {
hv = 0.0;
} else {
numberOfObjectives = solutionSet.get(0).getNumberOfObjectives();
referencePoint = new Solution(numberOfObjectives);
updateReferencePoint(solutionSet);
if (numberOfObjectives == 2) {
solutionSet.sort(new ObjectiveComparator(numberOfObjectives - 1, true));
hv = get2DHV(solutionSet);
} else {
updateReferencePoint(solutionSet);
Front front = new Front(solutionSet.size(), numberOfObjectives, solutionSet);
hv = new WFGHV(numberOfObjectives, solutionSet.size(), referencePoint).getHV(front);
}
}
return hv;
}
public double computeHypervolume(SolutionSet solutionSet, Solution referencePoint) {
double hv = 0.0;
if (solutionSet.size() == 0) {
hv = 0.0;
} else {
numberOfObjectives = solutionSet.get(0).getNumberOfObjectives();
this.referencePoint = referencePoint;
if (numberOfObjectives == 2) {
solutionSet.sort(new ObjectiveComparator(numberOfObjectives - 1, true));
hv = get2DHV(solutionSet);
} else {
WFGHV wfg = new WFGHV(numberOfObjectives, solutionSet.size());
Front front = new Front(solutionSet.size(), numberOfObjectives, solutionSet);
hv = wfg.getHV(front, referencePoint);
}
}
return hv;
}
protected void crowdingDistanceSelection(Ranking ranking) {
population.clear();
int rankingIndex = 0;
while (populationIsNotFull()) {
if (subfrontFillsIntoThePopulation(ranking, rankingIndex)) {
addRankedSolutionsToPopulation(ranking, rankingIndex);
rankingIndex++;
} else {
computeCrowdingDistance(ranking, rankingIndex);
addLastRankedSolutions(ranking, rankingIndex);
}
}
}
/**
* Computes the HV contribution of the solutions
*
* @return
*/
public void computeHVContributions(SolutionSet solutionSet) {
double[] contributions = new double[solutionSet.size()];
double solutionSetHV = 0;
solutionSetHV = computeHypervolume(solutionSet);
for (int i = 0; i < solutionSet.size(); i++) {
Solution currentPoint = solutionSet.get(i);
solutionSet.remove(i);
if (numberOfObjectives == 2) {
contributions[i] = solutionSetHV - get2DHV(solutionSet);
} else {
Front front = new Front(solutionSet.size(), numberOfObjectives, solutionSet);
double hv = new WFGHV(numberOfObjectives, solutionSet.size(), referencePoint).getHV(front);
contributions[i] = solutionSetHV - hv;
}
solutionSet.add(i, currentPoint);
}
for (int i = 0; i < solutionSet.size(); i++) {
solutionSet.get(i).setCrowdingDistance(contributions[i]);
}
}
/**
* Computes the HV of a solutiontype set. REQUIRES: The problem is bi-objective REQUIRES: The
* setArchive is ordered in descending order by the second objective
*
* @return
*/
public double get2DHV(SolutionSet solutionSet) {
double hv = 0.0;
if (solutionSet.size() > 0) {
hv =
Math.abs(
(solutionSet.get(0).getObjective(0) - referencePoint.getObjective(0))
* (solutionSet.get(0).getObjective(1) - referencePoint.getObjective(1)));
for (int i = 1; i < solutionSet.size(); i++) {
double tmp =
Math.abs(
(solutionSet.get(i).getObjective(0) - referencePoint.getObjective(0))
* (solutionSet.get(i).getObjective(1)
- solutionSet.get(i - 1).getObjective(1)));
hv += tmp;
}
}
return hv;
}
/**
* Computes the HV contribution of a solutiontype in a solutiontype set. REQUIRES: the
* solutiontype belongs to the solutiontype set REQUIRES: the HV of the solutiontype set is
* computed beforehand and its value is passed as third parameter
*
* @return The hv contribution of the solutiontype
*/
public double computeSolutionHVContribution(
SolutionSet solutionSet, int solutionIndex, double solutionSetHV) {
double contribution;
Solution currentPoint = solutionSet.get(solutionIndex);
solutionSet.remove(solutionIndex);
if (numberOfObjectives == 2) {
contribution = solutionSetHV - get2DHV(solutionSet);
} else {
Front front = new Front(solutionSet.size(), numberOfObjectives, solutionSet);
double hv = new WFGHV(numberOfObjectives, solutionSet.size(), referencePoint).getHV(front);
contribution = solutionSetHV - hv;
}
solutionSet.add(solutionIndex, currentPoint);
solutionSet.get(solutionIndex).setCrowdingDistance(contribution);
return contribution;
}
protected boolean subfrontFillsIntoThePopulation(Ranking ranking, int rank) {
return ranking.getSubfront(rank).size() < (populationSize - population.size());
}
protected boolean populationIsNotFull() {
return population.size() < populationSize;
}
protected Ranking rankPopulation() throws JMetalException {
SolutionSet union = population.union(offspringPopulation);
return new Ranking(union);
}
protected SolutionSet evaluatePopulation(SolutionSet population) throws JMetalException {
evaluations += population.size();
return evaluator.evaluate(population, problem);
}