Fix function evaluations in ga

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sandeep singh chauhan
评论： Emily Kambalame 2022-8-26
I want to fix my number of maximum function evaluation as stopping criteria in ga. How can i do it?
  2 个评论
Geoff Hayes
Geoff Hayes 2016-1-26
Sandeep - do you mean that you want the genetic algorithm to iterate for some maximum number of iterations/generations?
sandeep singh chauhan
sandeep singh chauhan 2016-1-26
No, I want to use genetic algorithm that will stop with maximum function evaluations

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回答（2 个）

Brendan Hamm
Brendan Hamm 2016-1-26
This is controlled in the Generations property of the Genetic Algorithm options. Obtain the default options:
>> options = gaoptimset(@ga)
options =
PopulationType: 'doubleVector'
PopInitRange: []
PopulationSize: '50 when numberOfVariables <= 5, else 200'
EliteCount: '0.05*PopulationSize'
CrossoverFraction: 0.8000
ParetoFraction: []
MigrationDirection: 'forward'
MigrationInterval: 20
MigrationFraction: 0.2000
Generations: '100*numberOfVariables'
TimeLimit: Inf
FitnessLimit: -Inf
StallGenLimit: 50
StallTest: 'averageChange'
StallTimeLimit: Inf
TolFun: 1.0000e-06
TolCon: 1.0000e-03
InitialPopulation: []
InitialScores: []
NonlinConAlgorithm: 'auglag'
InitialPenalty: 10
PenaltyFactor: 100
PlotInterval: 1
CreationFcn: @gacreationuniform
FitnessScalingFcn: @fitscalingrank
SelectionFcn: @selectionstochunif
CrossoverFcn: @crossoverscattered
MutationFcn: {@mutationgaussian [1] [1]}
DistanceMeasureFcn: []
HybridFcn: []
Display: 'final'
PlotFcns: []
OutputFcns: []
Vectorized: 'off'
UseParallel: 0
Now you can change the Generations and pass this in to the options input of your call to ga
>> options.Generations = '200*numberOfVariables';
>> ga(...,options); % Fill in the ... with your function, constraints, etc.
  4 个评论
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UbuntuXenial
UbuntuXenial 2019-3-28
Can you please explain how to determine the dependence? I want to run GA/MOGA only up to certain MaxFunctionEvaluations but this isn't a valid optimoption for these algorithms.
Emily Kambalame
Emily Kambalame 2022-8-26
Hie sandeep singh chauhan, Brendan Hamm,UbuntuXenial
I also dont want to use the max generation but rather the maximum function evaluation as my stopping condition. How should i approach my problem? Take note that my constraints are satified using Epanet simulator and am NSGA 2 to optimise.

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Matt J
Matt J 2016-1-26
编辑：Matt J 2016-1-26
The following nested function strategy might be a way to cheat. Basically, it keeps a running count, funEvals, of the number of calls to the fitness function. When funEvals exceeds a specified MaxFunEvals, the FitnessFcn output is forced to -Inf, which I think must trigger the FitnessLimit stopping criterion.
function runEverything(MaxFunEvals)
funEvals=0;
bestFitness=inf;
[x,fval,exitflag,output,population,scores] = ga(@FitnessFcn,...);
fval=bestFitness;
function val = FitnessFcn(x)
...
bestFitness=min(bestFitness,val);
funEvals=funEvals+1; %increment counter
if funEvals>=MaxFunEvals
val=-inf;
end
end
end

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