/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet. This solution set must be an instancen <code>AdaptiveGridArchive</code></param>
/// <returns>the selected solution</returns>
public override object Execute(object obj)
{
try
{
AdaptiveGridArchive archive = (AdaptiveGridArchive)obj;
int selected;
int hypercube1 = archive.Grid.RandomOccupiedHypercube();
int hypercube2 = archive.Grid.RandomOccupiedHypercube();
if (hypercube1 != hypercube2)
{
if (archive.Grid.GetLocationDensity(hypercube1) < archive.Grid.GetLocationDensity(hypercube2))
{
selected = hypercube1;
}
else if (archive.Grid.GetLocationDensity(hypercube2) <
archive.Grid.GetLocationDensity(hypercube1))
{
selected = hypercube2;
}
else
{
if (JMetalRandom.NextDouble() < 0.5)
{
selected = hypercube2;
}
else
{
selected = hypercube1;
}
}
}
else
{
selected = hypercube1;
}
int bas = JMetalRandom.Next(0, archive.Size() - 1);
int cnt = 0;
while (cnt < archive.Size())
{
Solution individual = archive.Get((bas + cnt) % archive.Size());
if (archive.Grid.Location(individual) != selected)
{
cnt++;
}
else
{
return(individual);
}
}
return(archive.Get((bas + cnt) % archive.Size()));
}
catch (InvalidCastException ex)
{
Logger.Log.Error("Exception in " + this.GetType().FullName + ".Execute()", ex);
throw new Exception("Exception in " + this.GetType().FullName + ".Execute()");
}
}
/// <summary>
/// Tests two solutions to determine which one becomes be the guide of PAES algorithm
/// </summary>
/// <param name="solution"> The actual guide of PAES</param>
/// <param name="mutatedSolution">A candidate guide</param>
/// <param name="archive"></param>
/// <returns></returns>
private Solution Test(Solution solution, Solution mutatedSolution, AdaptiveGridArchive archive)
{
int originalLocation = archive.Grid.Location(solution);
int mutatedLocation = archive.Grid.Location(mutatedSolution);
if (originalLocation == -1)
{
return(new Solution(mutatedSolution));
}
if (mutatedLocation == -1)
{
return(new Solution(solution));
}
if (archive.Grid.GetLocationDensity(mutatedLocation) <
archive.Grid.GetLocationDensity(originalLocation))
{
return(new Solution(mutatedSolution));
}
return(new Solution(solution));
}
/// <summary>
/// Runs of the Paes 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 bisections = -1,
archiveSize = -1,
maxEvaluations = -1,
evaluations;
AdaptiveGridArchive archive;
Operator mutationOperator;
IComparer <Solution> dominance;
//Read the params
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "biSections", ref bisections);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "archiveSize", ref archiveSize);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "maxEvaluations", ref maxEvaluations);
//Read the operators
mutationOperator = this.Operators["mutation"];
//Initialize the variables
evaluations = 0;
archive = new AdaptiveGridArchive(archiveSize, bisections, this.Problem.NumberOfObjectives);
dominance = new DominanceComparator();
//-> Create the initial solution and evaluate it and his constraints
Solution solution = new Solution(this.Problem);
this.Problem.Evaluate(solution);
this.Problem.EvaluateConstraints(solution);
evaluations++;
// Add it to the archive
archive.Add(new Solution(solution));
//Iterations....
do
{
// Create the mutate one
Solution mutatedIndividual = new Solution(solution);
mutationOperator.Execute(mutatedIndividual);
this.Problem.Evaluate(mutatedIndividual);
this.Problem.EvaluateConstraints(mutatedIndividual);
evaluations++;
// Check dominance
int flag = dominance.Compare(solution, mutatedIndividual);
if (flag == 1)
{ //If mutate solution dominate
solution = new Solution(mutatedIndividual);
archive.Add(mutatedIndividual);
}
else if (flag == 0)
{ //If none dominate the other
if (archive.Add(mutatedIndividual))
{
solution = Test(solution, mutatedIndividual, archive);
}
}
} while (evaluations < maxEvaluations);
Result = archive;
return(archive);
}
