public double ComputeHypervolume(SolutionSet solutionSet, Solution referencePoint)
{
double hv = 0.0;
if (solutionSet.Size() == 0)
{
hv = 0.0;
}
else
{
this.numberOfObjectives = solutionSet.Get(0).NumberOfObjectives;
this.referencePoint = referencePoint;
if (this.numberOfObjectives == 2)
{
solutionSet.Sort(new ObjectiveComparator(this.numberOfObjectives - 1, true));
hv = Get2DHV(solutionSet);
}
else
{
WFGHV wfg = new WFGHV(this.numberOfObjectives, solutionSet.Size());
Front front = new Front(solutionSet.Size(), numberOfObjectives, solutionSet);
hv = wfg.GetHV(front, referencePoint);
}
}
return(hv);
}
public override Solution GetOffspring(SolutionSet solutionSet, int index)
{
Solution[] parents = new Solution[3];
Solution offSpring = null;
try
{
int r1, r2;
do
{
r1 = JMetalRandom.Next(0, solutionSet.Size() - 1);
} while (r1 == index);
do
{
r2 = JMetalRandom.Next(0, solutionSet.Size() - 1);
} while (r2 == index || r2 == r1);
parents[0] = solutionSet.Get(r1);
parents[1] = solutionSet.Get(r2);
parents[2] = solutionSet.Get(index);
offSpring = (Solution)crossover.Execute(new object[] { solutionSet.Get(index), parents });
}
catch (Exception ex)
{
Logger.Log.Error("Exception in " + this.GetType().FullName + ".GetOffSpring()", ex);
Console.Error.WriteLine("Exception in " + this.GetType().FullName + ".GetOffSpring()");
}
//Create a new solution, using DE
return(offSpring);
}
public double ComputeHypervolume(SolutionSet solutionSet)
{
double hv;
if (solutionSet.Size() == 0)
{
hv = 0.0;
}
else
{
numberOfObjectives = solutionSet.Get(0).NumberOfObjectives;
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 void LoadFront(SolutionSet solutionSet, int notLoadingIndex)
{
if (notLoadingIndex >= 0 && notLoadingIndex < solutionSet.Size())
{
NumberOfPoints = solutionSet.Size() - 1;
}
else
{
NumberOfPoints = solutionSet.Size();
}
NPoints = NumberOfPoints;
dimension = solutionSet.Get(0).NumberOfObjectives;
Points = new Point[NumberOfPoints];
int index = 0;
for (int i = 0; i < solutionSet.Size(); i++)
{
if (i != notLoadingIndex)
{
double[] vector = new double[dimension];
for (int j = 0; j < dimension; j++)
{
vector[j] = solutionSet.Get(i).Objective[j];
}
Points[index++] = new Point(vector);
}
}
}
/// <summary>
/// Computes the HV contribution of the solutions
/// </summary>
/// <param name="solutionSet"></param>
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).CrowdingDistance = contributions[i];
}
}
/// <summary>
/// Returns a matrix with distances between solutions in a <code>SolutionSet</code>.
/// </summary>
/// <param name="solutionSet">The <code>SolutionSet</code>.</param>
/// <returns>a matrix with distances.</returns>
public double[][] DistanceMatrix(SolutionSet solutionSet)
{
Solution solutionI, solutionJ;
//The matrix of distances
double[][] distance = new double[solutionSet.Size()][];
for (int i = 0; i < solutionSet.Size(); i++)
{
distance[i] = new double[solutionSet.Size()];
}
//-> Calculate the distances
for (int i = 0; i < solutionSet.Size(); i++)
{
distance[i][i] = 0.0;
solutionI = solutionSet.Get(i);
for (int j = i + 1; j < solutionSet.Size(); j++)
{
solutionJ = solutionSet.Get(j);
distance[i][j] = this.DistanceBetweenObjectives(solutionI, solutionJ);
distance[j][i] = distance[i][j];
}
}
//->Return the matrix of distances
return(distance);
}
/// <summary>
/// Executes the operation
/// </summary>
/// <param name="obj">An object containing the population and the position (index) of the current individual</param>
/// <returns>An object containing the three selected parents</returns>
public override object Execute(object obj)
{
object[] parameters = (object[])obj;
SolutionSet population = (SolutionSet)parameters[0];
int index = (int)parameters[1];
Solution[] parents = new Solution[3];
int r1, r2, r3;
if (population.Size() < 4)
{
throw new Exception("DifferentialEvolutionSelection: the population has less than four solutions");
}
do
{
r1 = (int)(JMetalRandom.Next(0, population.Size() - 1));
} while (r1 == index);
do
{
r2 = (int)(JMetalRandom.Next(0, population.Size() - 1));
} while (r2 == index || r2 == r1);
do
{
r3 = (int)(JMetalRandom.Next(0, population.Size() - 1));
} while (r3 == index || r3 == r1 || r3 == r2);
parents[0] = population.Get(r1);
parents[1] = population.Get(r2);
parents[2] = population.Get(r3);
return(parents);
}
/// <summary>
/// Computes the feasibility ratio
/// </summary>
/// <param name="solutionSet"></param>
/// <returns>The ratio of feasible solutions</returns>
private double MeanOveralViolation(SolutionSet solutionSet)
{
double aux = 0.0;
for (int i = 0; i < solutionSet.Size(); i++)
{
aux += Math.Abs(solutionSet.Get(i).NumberOfViolatedConstraints *solutionSet.Get(i).OverallConstraintViolation);
}
return(aux / (double)solutionSet.Size());
}
/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet.</param>
/// <returns>An object representing a <code>SolutionSet<code> with the selected parents</returns>
public override object Execute(object obj)
{
SolutionSet population = (SolutionSet)obj;
int populationSize = (int)Parameters["populationSize"];
SolutionSet result = new SolutionSet(populationSize);
//->Ranking the union
Ranking ranking = new Ranking(population);
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()))
{
//Asign crowding distance to individuals
distance.CrowdingDistanceAssignment(front, problem.NumberOfObjectives);
//Add the individuals of this front
for (int k = 0; k < front.Size(); k++)
{
result.Add(front.Get(k));
}
//Decrement remaint
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 containt individuals to insert
distance.CrowdingDistanceAssignment(front, problem.NumberOfObjectives);
front.Sort(crowdingComparator);
for (int k = 0; k < remain; k++)
{
result.Add(front.Get(k));
}
remain = 0;
}
return(result);
}
/// <summary>
/// Computes the feasibility ratio
/// </summary>
/// <param name="solutionSet"></param>
/// <returns>The ratio of feasible solutions</returns>
private double FeasibilityRatio(SolutionSet solutionSet)
{
double aux = 0.0;
for (int i = 0; i < solutionSet.Size(); i++)
{
if (solutionSet.Get(i).OverallConstraintViolation < 0)
{
aux = aux + 1.0;
}
}
return(aux / (double)solutionSet.Size());
}
/// <summary>
/// Return the index of the nearest solution in the solution set to a given solution
/// </summary>
/// <param name="solution"></param>
/// <param name="solutionSet"></param>
/// <returns>The index of the nearest solution; -1 if the solutionSet is empty</returns>
public int IndexToNearestSolutionInSolutionSpace(Solution solution, SolutionSet solutionSet)
{
int index = -1;
double minimumDistance = double.MaxValue;
try
{
for (int i = 0; i < solutionSet.Size(); i++)
{
double distance = 0;
distance = this.DistanceBetweenSolutions(solution, solutionSet.Get(i));
if (distance < minimumDistance)
{
minimumDistance = distance;
index = i;
}
}
}
catch (Exception ex)
{
Logger.Log.Error("Exception in " + this.GetType().FullName + ".IndexToNearestSolutionInSolutionSpace()", ex);
Console.WriteLine("Exception in " + this.GetType().FullName + ".IndexToNearestSolutionInSolutionSpace()");
}
return(index);
}
/// <summary>
/// Computes the HV of a solution set.
/// REQUIRES: The problem is bi-objective
/// REQUIRES: The archive is ordered in descending order by the second objective
/// </summary>
/// <param name="solutionSet"></param>
/// <returns></returns>
public double Get2DHV(SolutionSet solutionSet)
{
double hv = 0.0;
if (solutionSet.Size() > 0)
{
hv = Math.Abs((solutionSet.Get(0).Objective[0] - referencePoint.Objective[0]) * (solutionSet.Get(0).Objective[1] - referencePoint.Objective[1]));
for (int i = 1; i < solutionSet.Size(); i++)
{
double tmp = Math.Abs((solutionSet.Get(i).Objective[0] - referencePoint.Objective[0]) * (solutionSet.Get(i).Objective[1] - solutionSet.Get(i - 1).Objective[1]));
hv += tmp;
}
}
return(hv);
}
public int GetLessContributorHV(SolutionSet set)
{
Front wholeFront = new Front();
wholeFront.LoadFront(set, -1);
int index = 0;
double contribution = double.PositiveInfinity;
for (int i = 0; i < set.Size(); i++)
{
double[] v = new double[set.Get(i).NumberOfObjectives];
for (int j = 0; j < v.Length; j++)
{
v[j] = set.Get(i).Objective[j];
}
Point p = new Point(v);
double aux = this.GetExclusiveHV(wholeFront, i);
if ((aux) < contribution)
{
index = i;
contribution = aux;
}
set.Get(i).CrowdingDistance = aux;
}
return(index);
}
/// <summary>
/// Updates the grid limits considering the solutions contained in a <code>SolutionSet</code>.
/// </summary>
/// <param name="solutionSet">The <code>SolutionSet</code> considered.</param>
private void UpdateLimits(SolutionSet solutionSet)
{
//Init the lower and upper limits
for (int obj = 0; obj < objectives; obj++)
{
//Set the lower limits to the max real
lowerLimits[obj] = double.MaxValue;
//Set the upper limits to the min real
upperLimits[obj] = double.MinValue;
}
//Find the max and min limits of objetives into the population
for (int ind = 0; ind < solutionSet.Size(); ind++)
{
Solution tmpIndividual = solutionSet.Get(ind);
for (int obj = 0; obj < objectives; obj++)
{
if (tmpIndividual.Objective[obj] < lowerLimits[obj])
{
lowerLimits[obj] = tmpIndividual.Objective[obj];
}
if (tmpIndividual.Objective[obj] > upperLimits[obj])
{
upperLimits[obj] = tmpIndividual.Objective[obj];
}
}
}
}
public override Solution GetOffspring(SolutionSet solutionSet, SolutionSet archive)
{
Solution[] parents = new Solution[2];
Solution offSpring = null;
try
{
parents[0] = (Solution)selection.Execute(solutionSet);
if (archive.Size() > 0)
{
parents[1] = (Solution)selection.Execute(archive);
}
else
{
parents[1] = (Solution)selection.Execute(solutionSet);
}
Solution[] children = (Solution[])crossover.Execute(parents);
offSpring = children[0];
//Create a new solution, using DE
}
catch (Exception ex)
{
Logger.Log.Error("Error in: " + this.GetType().FullName + ".GetOffspring()", ex);
Console.Error.WriteLine("Error in: " + this.GetType().FullName);
}
return(offSpring);
}
/// <summary>
/// Assigns fitness for all the solutions.
/// </summary>
public void FitnessAssign()
{
double[] strength = new double[solutionSet.Size()];
double[] rawFitness = new double[solutionSet.Size()];
double kDistance;
//Calculate the strength value
// strength(i) = |{j | j <- SolutionSet and i dominate j}|
for (int i = 0; i < solutionSet.Size(); i++)
{
for (int j = 0; j < solutionSet.Size(); j++)
{
if (dominance.Compare(solutionSet.Get(i), solutionSet.Get(j)) == -1)
{
strength[i] += 1.0;
}
}
}
//Calculate the raw fitness
// rawFitness(i) = |{sum strenght(j) | j <- SolutionSet and j dominate i}|
for (int i = 0; i < solutionSet.Size(); i++)
{
for (int j = 0; j < solutionSet.Size(); j++)
{
if (dominance.Compare(solutionSet.Get(i), solutionSet.Get(j)) == 1)
{
rawFitness[i] += strength[j];
}
}
}
// Add the distance to the k-th individual. In the reference paper of SPEA2,
// k = sqrt(population.size()), but a value of k = 1 recommended. See
// http://www.tik.ee.ethz.ch/pisa/selectors/spea2/spea2_documentation.txt
int k = 1;
for (int i = 0; i < distanceMatrix.Length; i++)
{
Array.Sort(distanceMatrix[i]);
kDistance = 1.0 / (distanceMatrix[i][k] + 2.0); // Calcule de D(i) distance
solutionSet.Get(i).Fitness = rawFitness[i] + kDistance;
}
}
/// <summary>
/// Tries to update the reference set one with a <code>Solution</code>.
/// </summary>
/// <param name="solution">The <code>Solution</code></param>
/// <returns>true if the <code>Solution</code> has been inserted, false
/// otherwise.</returns>
public bool RefSet1Test(Solution solution)
{
bool dominated = false;
int flag;
int i = 0;
while (i < refSet1.Size())
{
flag = dominance.Compare(solution, refSet1.Get(i));
if (flag == -1)
{ //This is: solution dominates
refSet1.Remove(i);
}
else if (flag == 1)
{
dominated = true;
i++;
}
else
{
flag = equal.Compare(solution, refSet1.Get(i));
if (flag == 0)
{
return(true);
}
i++;
}
}
if (!dominated)
{
solution.UnMarked();
if (refSet1.Size() < refSet1Size)
{ //refSet1 isn't full
refSet1.Add(solution);
}
else
{
archive.Add(solution);
}
}
else
{
return(false);
}
return(true);
}
/// <summary>
///
/// </summary>
/// <param name="cid">the id of current subproblem</param>
/// <param name="type">1 - whole population probability; otherwise - whole neighborhood probability</param>
/*public int ACOrSelection4(int cid, int type)
* {
* int ss;
* ss = neighborhood[cid].Length;
* double r;
* int b = neighborhood[cid][0];
* Solution[] parents = new Solution[ss];
* double[] fitness = new double[ss];
* Solution[] parent = new Solution[populationSize];
* double[] fit = new double[populationSize];
* double sum = 0;
* double[] pro = new double[ss];
* double[] p = new double[populationSize];
* double a1 = 0;
* double a2 = 0;
*
* if (type == 1)
* {
* for (int i = 0; i < ss; i++)
* {
* parents[i] = population.Get(neighborhood[cid][i]);
* fitness[i] = 1 / FitnessFunction(parents[i], lambda[cid]);
* sum = sum + fitness[i];
* }
* for (int j = 0; j < ss; j++)
* {
* pro[j] = fitness[j] / sum;
* }
* r = JMetalRandom.NextDouble();
* for (int k = 0; k < pro.Length; k++)
* {
* a2 = a2 + pro[k];
* if (r < a2 && r >= a1)
* {
* b = neighborhood[cid][k];
* break;
* }
* a1 = a1 + pro[k];
* }
* }
* else
* {
* for (int i = 0; i < populationSize; i++)
* {
* parent[i] = population.Get(i);
* fit[i] = 1 / FitnessFunction(parent[i], lambda[cid]);
* sum = sum + fit[i];
* }
* for (int j = 0; j < populationSize; j++)
* {
* p[j] = fit[j] / sum;
* }
* r = JMetalRandom.NextDouble();
* for (int k = 0; k < p.Length; k++)
* {
* a2 = a2 + p[k];
* if (r < a2 && r >= a1)
* {
* b = k;
* break;
* }
* a1 = a1 + p[k];
* }
* }
*
* return b;
* }*/
/// <summary>
///
/// </summary>
/// <param name="indiv">child solution</param>
/// <param name="id">the id of current subproblem</param>
/// <param name="type">update solutions in - neighborhood (1) or whole population (otherwise)</param>
private void UpdateProblem(Solution indiv, int id, int type)
{
int size;
int time;
time = 0;
if (type == 1)
{
size = neighborhood[id].Length;
}
else
{
size = population.Size();
}
int[] perm = new int[size];
Utils.RandomPermutation(perm, size);
for (int i = 0; i < size; i++)
{
int k;
if (type == 1)
{
k = neighborhood[id][perm[i]];
}
else
{
k = perm[i]; // calculate the values of objective function regarding the current subproblem
}
double f1, f2;
f1 = FitnessFunction(population.Get(k), lambda[k]);
f2 = FitnessFunction(indiv, lambda[k]);
if (f2 < f1)
{
population.Replace(k, new Solution(indiv));
time++;
}
// the maximal number of solutions updated is not allowed to exceed 'limit'
if (time >= nr)
{
return;
}
}
}
/// <summary>
/// Assigns crowding distances to all solutions in a <code>SolutionSet</code>.
/// </summary>
/// <param name="solutionSet">The <code>SolutionSet</code>.</param>
/// <param name="nObjs">Number of objectives.</param>
public void CrowdingDistanceAssignment(SolutionSet solutionSet, int nObjs)
{
int size = solutionSet.Size();
if (size == 0)
{
return;
}
if (size == 1)
{
solutionSet.Get(0).CrowdingDistance = double.PositiveInfinity;
return;
}
if (size == 2)
{
solutionSet.Get(0).CrowdingDistance = double.PositiveInfinity;
solutionSet.Get(1).CrowdingDistance = double.PositiveInfinity;
return;
}
//Use a new SolutionSet to evite alter original solutionSet
SolutionSet front = new SolutionSet(size);
for (int i = 0; i < size; i++)
{
front.Add(solutionSet.Get(i));
}
for (int i = 0; i < size; i++)
{
front.Get(i).CrowdingDistance = 0.0;
}
double objetiveMaxn;
double objetiveMinn;
double distance;
for (int i = 0; i < nObjs; i++)
{
// Sort the population by Obj n
front.Sort(new ObjectiveComparator(i));
objetiveMinn = front.Get(0).Objective[i];
objetiveMaxn = front.Get(front.Size() - 1).Objective[i];
//Set de crowding distance
front.Get(0).CrowdingDistance = double.PositiveInfinity;
front.Get(size - 1).CrowdingDistance = double.PositiveInfinity;
for (int j = 1; j < size - 1; j++)
{
distance = front.Get(j + 1).Objective[i] - front.Get(j - 1).Objective[i];
distance = distance / (objetiveMaxn - objetiveMinn);
distance += front.Get(j).CrowdingDistance;
front.Get(j).CrowdingDistance = distance;
}
}
}
/// <summary>
/// Constructor.
/// Creates a new instance of Spea2Fitness for a given <code>SolutionSet</code>.
/// </summary>
/// <param name="solutionSet">The <code>SolutionSet</code></param>
public Spea2Fitness(SolutionSet solutionSet)
{
this.distanceMatrix = distance.DistanceMatrix(solutionSet);
this.solutionSet = solutionSet;
for (int i = 0; i < solutionSet.Size(); i++)
{
solutionSet.Get(i).Location = i;
}
}
/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet.</param>
/// <returns>An object representing an array with the selected parents</returns>
public override object Execute(object obj)
{
SolutionSet population = (SolutionSet)obj;
int pos1, pos2;
pos1 = JMetalRandom.Next(0, population.Size() - 1);
pos2 = JMetalRandom.Next(0, population.Size() - 1);
while ((pos1 == pos2) && (population.Size() > 1))
{
pos2 = JMetalRandom.Next(0, population.Size() - 1);
}
Solution[] parents = new Solution[2];
parents[0] = population.Get(pos1);
parents[1] = population.Get(pos2);
return(parents);
}
/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet</param>
/// <returns>The selected solution</returns>
public override object Execute(object obj)
{
SolutionSet population = (SolutionSet)obj;
if (index == 0) //Create the permutation
{
a = (new PermutationUtility()).IntPermutation(population.Size());
}
Solution solution1, solution2;
solution1 = population.Get(a[index]);
solution2 = population.Get(a[index + 1]);
index = (index + 2) % population.Size();
int flag = dominance.Compare(solution1, solution2);
if (flag == -1)
{
return(solution1);
}
else if (flag == 1)
{
return(solution2);
}
else if (solution1.CrowdingDistance > solution2.CrowdingDistance)
{
return(solution1);
}
else if (solution2.CrowdingDistance > solution1.CrowdingDistance)
{
return(solution2);
}
else if (JMetalRandom.NextDouble() < 0.5)
{
return(solution1);
}
else
{
return(solution2);
}
}
/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet.</param>
/// <returns>the best solution found</returns>
public override object Execute(object obj)
{
SolutionSet solutionSet = (SolutionSet)obj;
if (solutionSet.Size() == 0)
{
return(null);
}
int bestSolution;
bestSolution = 0;
for (int i = 1; i < solutionSet.Size(); i++)
{
if (comparator.Compare(solutionSet.Get(i), solutionSet.Get(bestSolution)) < 0)
{
bestSolution = i;
}
}
return(bestSolution);
}
/// <summary>
/// Performs the operation
/// </summary>
/// <param name="obj">Object representing a SolutionSet</param>
/// <returns>The selected solution</returns>
public override object Execute(object obj)
{
SolutionSet solutionSet = (SolutionSet)obj;
Solution solution1, solution2;
solution1 = solutionSet.Get(JMetalRandom.Next(0, solutionSet.Size() - 1));
solution2 = solutionSet.Get(JMetalRandom.Next(0, solutionSet.Size() - 1));
if (solutionSet.Size() >= 2)
{
while (solution1 == solution2)
{
solution2 = solutionSet.Get(JMetalRandom.Next(0, solutionSet.Size() - 1));
}
}
int flag = comparator.Compare(solution1, solution2);
if (flag == -1)
{
return(solution1);
}
else if (flag == 1)
{
return(solution2);
}
else
if (JMetalRandom.NextDouble() < 0.5)
{
return(solution1);
}
else
{
return(solution2);
}
}
/// <summary>
/// Apply a mutation operator to some particles in the swarm
/// </summary>
/// <param name="actualIteration"></param>
/// <param name="totalIterations"></param>
private void MopsoMutation(int actualIteration, int totalIterations)
{
for (int i = 0; i < particles.Size(); i++)
{
if ((i % 6) == 0)
{
polynomialMutation.Execute(particles.Get(i));
}
}
}
/// <summary>
/// Returns the minimum distance from a <code>Solution</code> to a
/// <code>SolutionSet according to the encodings.variable values</code>.
/// </summary>
/// <param name="solution">The <code>Solution</code></param>
/// <param name="solutionSet">The <code>SolutionSet</code>.</param>
/// <returns>The minimum distance between solution and the set.</returns>
public double DistanceToSolutionSetInSolutionSpace(Solution solution, SolutionSet solutionSet)
{
//At start point the distance is the max
double distance = double.MaxValue;
// found the min distance respect to population
for (int i = 0; i < solutionSet.Size(); i++)
{
double aux = this.DistanceBetweenSolutions(solution, solutionSet.Get(i));
if (aux < distance)
{
distance = aux;
}
}
//->Return the best distance
return(distance);
}
/// <summary>
/// Updates the grid adding solutions contained in a specific
/// <code>SolutionSet</code>.
/// <b>REQUIRE</b> The grid limits must have been previously calculated.
/// </summary>
/// <param name="solutionSet">The <code>SolutionSet</code> considered.</param>
private void AddSolutionSet(SolutionSet solutionSet)
{
//Calculate the location of all individuals and update the grid
MostPopulated = 0;
int location;
for (int ind = 0; ind < solutionSet.Size(); ind++)
{
location = Location(solutionSet.Get(ind));
hypercubes[location]++;
if (hypercubes[location] > hypercubes[MostPopulated])
{
MostPopulated = location;
}
}
//The grid has been updated, so also update ocuppied's hypercubes
CalculateOccupied();
}
public Solution GetBest(double w1, double w2, double w3)
{
var size = _solutions.Size();
_solution = -1;
var min = double.MaxValue;
double wsum = -1;
for (var i = 0; i < size; i++)
{
wsum = w1 * _f1Scaled[i] + w2 * _f2Scaled[i] + w3 * _f3Scaled[i];
if (!(wsum < min))
{
continue;
}
min = wsum;
_solution = i;
}
//Console.WriteLine("Best solution: " + _solution + " wsum= " + wsum);
return(_solutions.Get(_solution));
}
/// <summary>
/// Updates the reference point
/// </summary>
/// <param name="solutionSet"></param>
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).Objective[j])
{
maxObjectives[j] = solutionSet.Get(i).Objective[j];
}
}
}
for (int i = 0; i < referencePoint.NumberOfObjectives; i++)
{
referencePoint.Objective[i] = maxObjectives[i] + offset;
}
}
/// <summary>
/// Runs the SMS-EMOA 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;
double offset = 100.0;
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;
//Read the parameters
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "populationSize", ref populationSize);
JMetalCSharp.Utils.Utils.GetIntValueFromParameter(this.InputParameters, "maxEvaluations", ref maxEvaluations);
JMetalCSharp.Utils.Utils.GetIndicatorsFromParameters(this.InputParameters, "indicators", ref indicators);
JMetalCSharp.Utils.Utils.GetDoubleValueFromParameter(this.InputParameters, "offset", ref offset);
//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);
Problem.Evaluate(newSolution);
Problem.EvaluateConstraints(newSolution);
evaluations++;
population.Add(newSolution);
}
// Generations ...
while (evaluations < maxEvaluations)
{
// select parents
offspringPopulation = new SolutionSet(populationSize);
List <Solution> selectedParents = new List <Solution>();
Solution[] parents = new Solution[0];
while (selectedParents.Count < 2)
{
object selected = selectionOperator.Execute(population);
try
{
Solution parent = (Solution)selected;
selectedParents.Add(parent);
}
catch (InvalidCastException e)
{
parents = (Solution[])selected;
selectedParents.AddRange(parents);
}
}
parents = selectedParents.ToArray <Solution>();
// crossover
Solution[] offSpring = (Solution[])crossoverOperator.Execute(parents);
// mutation
mutationOperator.Execute(offSpring[0]);
// evaluation
Problem.Evaluate(offSpring[0]);
Problem.EvaluateConstraints(offSpring[0]);
// insert child into the offspring population
offspringPopulation.Add(offSpring[0]);
evaluations++;
// Create the solutionSet union of solutionSet and offSpring
union = ((SolutionSet)population).Union(offspringPopulation);
// Ranking the union (non-dominated sorting)
Ranking ranking = new Ranking(union);
// ensure crowding distance values are up to date
// (may be important for parent selection)
for (int j = 0; j < population.Size(); j++)
{
population.Get(j).CrowdingDistance = 0.0;
}
SolutionSet lastFront = ranking.GetSubfront(ranking.GetNumberOfSubfronts() - 1);
if (lastFront.Size() > 1)
{
double[][] frontValues = lastFront.WriteObjectivesToMatrix();
int numberOfObjectives = Problem.NumberOfObjectives;
// STEP 1. Obtain the maximum and minimum values of the Pareto front
double[] maximumValues = utils.GetMaximumValues(union.WriteObjectivesToMatrix(), numberOfObjectives);
double[] minimumValues = utils.GetMinimumValues(union.WriteObjectivesToMatrix(), numberOfObjectives);
// STEP 2. Get the normalized front
double[][] normalizedFront = utils.GetNormalizedFront(frontValues, maximumValues, minimumValues);
// compute offsets for reference point in normalized space
double[] offsets = new double[maximumValues.Length];
for (int i = 0; i < maximumValues.Length; i++)
{
offsets[i] = offset / (maximumValues[i] - minimumValues[i]);
}
// STEP 3. Inverse the pareto front. This is needed because the original
//metric by Zitzler is for maximization problems
double[][] invertedFront = utils.InvertedFront(normalizedFront);
// shift away from origin, so that boundary points also get a contribution > 0
for (int j = 0, lj = invertedFront.Length; j < lj; j++)
{
var point = invertedFront[j];
for (int i = 0; i < point.Length; i++)
{
point[i] += offsets[i];
}
}
// calculate contributions and sort
double[] contributions = HvContributions(invertedFront);
for (int i = 0; i < contributions.Length; i++)
{
// contribution values are used analogously to crowding distance
lastFront.Get(i).CrowdingDistance = contributions[i];
}
lastFront.Sort(new CrowdingDistanceComparator());
}
// all but the worst are carried over to the survivor population
SolutionSet front = null;
population.Clear();
for (int i = 0; i < ranking.GetNumberOfSubfronts() - 1; i++)
{
front = ranking.GetSubfront(i);
for (int j = 0; j < front.Size(); j++)
{
population.Add(front.Get(j));
}
}
for (int i = 0; i < lastFront.Size() - 1; i++)
{
population.Add(lastFront.Get(i));
}
// This piece of code shows how to use the indicator object into the code
// of SMS-EMOA. 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 rnk = new Ranking(population);
Result = rnk.GetSubfront(0);
return(Result);
}