/// <summary>
/// Initialize all parameter of the algorithm
/// </summary>
public void InitParams()
{
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "swarmSize", ref swarmSize);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "archiveSize", ref archiveSize);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "maxIterations", ref maxIterations);
JMetalCSharp.Utils.Utils.GetIndicatorsFromParameters(this.InputParameters, "indicators", ref indicators);
polynomialMutation = this.Operators["mutation"];
parallelEvaluator.StartParallelRunner(this.Problem);;
iteration = 1;
particles = new SolutionSet(swarmSize);
best = new Solution[swarmSize];
Leaders = new CrowdingArchive(archiveSize, this.Problem.NumberOfObjectives);
// Create comparators for dominance and crowding distance
dominance = new DominanceComparator();
crowdingDistanceComparator = new CrowdingDistanceComparator();
distance = new Distance();
// Create the speed_ vector
speed = new double[swarmSize][];
for (var i = 0; i < swarmSize; i++)
{
speed[i] = new double[this.Problem.NumberOfVariables];
}
deltaMax = new double[this.Problem.NumberOfVariables];
deltaMin = new double[this.Problem.NumberOfVariables];
for (int i = 0; i < this.Problem.NumberOfVariables; i++)
{
deltaMax[i] = (this.Problem.UpperLimit[i] - this.Problem.LowerLimit[i]) / 2.0;
deltaMin[i] = -deltaMax[i];
}
}
/// <summary>
/// Runs the NSGA-II algorithm.
/// </summary>
/// <returns>a <code>SolutionSet</code> that is a set of non dominated solutions as a result of the algorithm execution</returns>
public override SolutionSet Execute()
{
int populationSize = -1;
int maxEvaluations = -1;
int evaluations;
JMetalCSharp.QualityIndicator.QualityIndicator indicators = null; // QualityIndicator object
int requiredEvaluations; // Use in the example of use of the
// indicators object (see below)
SolutionSet population;
SolutionSet offspringPopulation;
SolutionSet union;
Operator mutationOperator;
Operator crossoverOperator;
Operator selectionOperator;
Distance distance = new Distance();
//Read the parameters
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "maxEvaluations", ref maxEvaluations);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "populationSize", ref populationSize);
JMetalCSharp.Utils.Utils.GetIndicatorsFromParameters(this.InputParameters, "indicators", ref indicators);
parallelEvaluator.StartParallelRunner(Problem);;
//Initialize the variables
population = new SolutionSet(populationSize);
evaluations = 0;
requiredEvaluations = 0;
//Read the operators
mutationOperator = Operators["mutation"];
crossoverOperator = Operators["crossover"];
selectionOperator = Operators["selection"];
// Create the initial solutionSet
Solution newSolution;
for (int i = 0; i < populationSize; i++)
{
newSolution = new Solution(Problem);
parallelEvaluator.AddTaskForExecution(new object[] { newSolution });;
}
List <Solution> solutionList = (List <Solution>)parallelEvaluator.ParallelExecution();
foreach (Solution solution in solutionList)
{
population.Add(solution);
evaluations++;
}
// Generations
while (evaluations < maxEvaluations)
{
// Create the offSpring solutionSet
offspringPopulation = new SolutionSet(populationSize);
Solution[] parents = new Solution[2];
for (int i = 0; i < (populationSize / 2); i++)
{
if (evaluations < maxEvaluations)
{
//obtain parents
parents[0] = (Solution)selectionOperator.Execute(population);
parents[1] = (Solution)selectionOperator.Execute(population);
Solution[] offSpring = (Solution[])crossoverOperator.Execute(parents);
mutationOperator.Execute(offSpring[0]);
mutationOperator.Execute(offSpring[1]);
parallelEvaluator.AddTaskForExecution(new object[] { offSpring[0] });;
parallelEvaluator.AddTaskForExecution(new object[] { offSpring[1] });;
}
}
List <Solution> solutions = (List <Solution>)parallelEvaluator.ParallelExecution();
foreach (Solution solution in solutions)
{
offspringPopulation.Add(solution);
evaluations++;
}
// Create the solutionSet union of solutionSet and offSpring
union = ((SolutionSet)population).Union(offspringPopulation);
// Ranking the union
Ranking ranking = new Ranking(union);
int remain = populationSize;
int index = 0;
SolutionSet front = null;
population.Clear();
// Obtain the next front
front = ranking.GetSubfront(index);
while ((remain > 0) && (remain >= front.Size()))
{
//Assign crowding distance to individuals
distance.CrowdingDistanceAssignment(front, Problem.NumberOfObjectives);
//Add the individuals of this front
for (int k = 0; k < front.Size(); k++)
{
population.Add(front.Get(k));
}
//Decrement remain
remain = remain - front.Size();
//Obtain the next front
index++;
if (remain > 0)
{
front = ranking.GetSubfront(index);
}
}
// Remain is less than front(index).size, insert only the best one
if (remain > 0)
{ // front contains individuals to insert
distance.CrowdingDistanceAssignment(front, Problem.NumberOfObjectives);
front.Sort(new CrowdingComparator());
for (int k = 0; k < remain; k++)
{
population.Add(front.Get(k));
}
remain = 0;
}
// This piece of code shows how to use the indicator object into the code
// of NSGA-II. In particular, it finds the number of evaluations required
// by the algorithm to obtain a Pareto front with a hypervolume higher
// than the hypervolume of the true Pareto front.
if ((indicators != null) &&
(requiredEvaluations == 0))
{
double HV = indicators.GetHypervolume(population);
if (HV >= (0.98 * indicators.TrueParetoFrontHypervolume))
{
requiredEvaluations = evaluations;
}
}
}
// Return as output parameter the required evaluations
SetOutputParameter("evaluations", requiredEvaluations);
// Return the first non-dominated front
Ranking rank = new Ranking(population);
Result = rank.GetSubfront(0);
return(this.Result);
}
