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/// ------------------------------------------------------
/// SwarmOps - Numeric and heuristic optimization for C#
/// Copyright (C) 2003-2011 Magnus Erik Hvass Pedersen.
/// Please see the file license.txt for license details.
/// SwarmOps on the internet: http://www.Hvass-Labs.org/
/// ------------------------------------------------------
namespace SwarmOps
{
/// <summary>
/// Performs a number of optimization runs and returns the
/// minimum fitness found. Respects feasibility (constraint
/// satisfaction.)
/// This does NOT allow for Preemptive Fitness Evaluation!
/// </summary>
public class RepeatMin : Repeat
{
#region Constructors.
/// <summary>
/// Construct the object.
/// </summary>
/// <param name="optimizer">Optimizer to use.</param>
/// <param name="numRuns">Number of optimization runs to perform.</param>
public RepeatMin(Optimizer optimizer, int numRuns)
: base(optimizer, numRuns)
{
}
#endregion
#region Base-class overrides.
/// <summary>
/// Return problem-name.
/// </summary>
public override string Name
{
get { return "RepeatMin(" + Optimizer.Name + ")"; }
}
/// <summary>
/// Return minimum fitness possible. This is the same as
/// the minimum fitness of the Optimizer in question.
/// </summary>
public override double MinFitness
{
get { return Optimizer.MinFitness; }
}
/// <summary>
/// Compute the fitness by repeating a number of optimization runs
/// and taking the best fitness achieved in any one of these runs.
/// </summary>
/// <param name="parameters">Parameters to use for the Optimizer.</param>
/// <param name="fitnessLimit">Preemptive Fitness Limit</param>
/// <returns>Fitness value.</returns>
public override double Fitness(double[] parameters, double fitnessLimit)
{
// Best fitness found so far is initialized to the worst possible fitness.
double fitness = Optimizer.MaxFitness;
// Best feasibility found so far is initialized to the worst possible (infeasible).
bool feasible = false;
// Perform a number of optimization runs.
for (int i = 0; i < NumRuns; i++)
{
// Perform one optimization run.
Result result = Optimizer.Optimize(parameters, fitnessLimit);
// Update the best fitness found so far, if improvement.
if (Tools.BetterFeasibleFitness(feasible, result.Feasible, fitness, result.Fitness))
{
fitness = result.Fitness;
feasible = result.Feasible;
}
}
return fitness;
}
#endregion
}
}
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