getBestMemberData

View best member data after optimization

Since R2025a

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    Syntax

    optdata = getBestMemberData(obj)

    Description

    optdata = getBestMemberData(obj) returns an object representing the best member data associated with the optimizer specified in obj.

    example

    Examples

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    Open Live Script

    Create a dipole antenna resonating at 75 MHz and calculate its maximum directivity.

    Choose its length and width as design variables. Provide lower and upper bounds of length and width.

    referenceAnt = design(dipole,75e6);
InitialDirectivity = max(max(pattern(referenceAnt,75e6)))
    InitialDirectivity = 
2.1002

    length_lb = 3; % Lower bound for length
length_ub = 7; % Upper bound for length
width_lb = 0.11; % Lower bound for width
width_ub = 0.13; % Upper bound for width
Bounds = [length_lb width_lb; length_ub width_ub];

    Use the SADEA optimizer to optimize this dipole antenna for its directivity. Specify an evaluation function for optimization using the CustomEvaluationFunction property of the OptimizerSADEA object. The evaluation function used in this example is defined at the end of this example.

    s = OptimizerSADEA(Bounds);
s.CustomEvaluationFunction = @customEvaluationOnlyObjective;

    Validate the optimizer setup.

    validateSetup(s)
    ans = logical
   1

    Run the optimization for 100 iterations.

    figure
optimizeWithPlots(s,100);

    Figure contains 2 axes objects. Axes object 1 with title Population Diversity Plot, xlabel Number of Iterations, ylabel Population Diversity contains an object of type line. Axes object 2 with title Convergence Trend Plot, xlabel Number of Iterations, ylabel Fitness contains an object of type line.

    View the best member data.

    bestDesign = s.getBestMemberData
    bestDesign = 
  bestMemberData with properties:

             member: [4.8004 0.1100]
       performances: -4.7895
            fitness: -4.7895
    bestIterationId: 72


    bestDesignValues = bestDesign.member
    bestDesignValues = 1×2

    4.8004    0.1100

    Update the reference antenna with best design values from the optimizer. Calculate directivity of the optimized design.

    Observe an increase in directivity value after optimization.

    referenceAnt.Length = bestDesignValues(1);
referenceAnt.Width = bestDesignValues(2);
postOptimizationDirectivity = max(max(pattern(referenceAnt,75e6)))
    postOptimizationDirectivity = 
4.7895

    View the surrogate model data used for prediction.

    InitialData = s.getInitializationData
    InitialData = 
  initializationData with properties:

         members: [30×2 double]
    performances: [30×1 double]
         fitness: [30×1 double]

    View the data for all iterations.

    iterData = s.getIterationData
    iterData = 
  iterationData with properties:

         members: [75×2 double]
    performances: [75×1 double]
         fitness: [75×1 double]

    Check if the algorithm has converged.

    ConvergenceFlag = s.isConverged
    ConvergenceFlag = logical
   1

    Check how many times the evaluation function is computed.

    numEvaluations = s.getNumberOfEvaluations
    numEvaluations = 
105

    Plot the convergence trend.

    s.showConvergenceTrend

    Figure contains an axes object. The axes object with title Convergence Trend Plot, xlabel Number of Iterations, ylabel Fitness contains an object of type line.

    This code defines the evaluation function used in this example.

    function fitness = customEvaluationOnlyObjective(designVariables)
    
        % Create geometry
        ant = design(dipole,75e6);
        ant.Length = designVariables(1);
        ant.Width = designVariables(2);
    
        % Calculate directivity
        % Optimizer always minimizes the objective hence reverse the sign to maximize gain.
        objective = max(max(pattern(ant,75e6)));
        objective = -objective; 
        
        % As there are no constraints, fitness equals objective.
        fitness = objective;
    
end

    Input Arguments

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    Optimizer, specified as an OptimizerSADEA or OptimizerTRSADEA object. The function returns the best member data associated with the optimizer specified in obj.

    Example: OptimizerSADEA([1;2])

    Output Arguments

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    Best member data after optimization, returned as a bestMemberData object with properties representing the optimization results:

    • member – Optimized design variable values

    • performances – Vector of objective and constraints, with first element as objective and the rest as constraints

    • fitness – Summation of objective and weighted constraint values

    • bestIterationId – Iteration ID of best value

    Version History

    Introduced in R2025a

    See Also

    Objects