gamultiobj output function error
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Maximilian Ernst
on 31 Aug 2016
Edited: Modess Seyednezhad
on 31 May 2020
Hi,
I have a multiobjective opimization problem and want to solve it with gamultiobj. I want to save the optimized values of my objective functions after every iteration in an array. I found the example code for the output function here: http://de.mathworks.com/help/optim/ug/output-functions.html . But when I apply the example code to my problem, like this:
function [history,searchdir] = runfmincon
FitnessFunction = @needfunction;
numberOfVariables = 8;
lb = zeros(1,8);
ub = [];
% Set up shared variables with OUTFUN
history.x = [];
history.fval = [];
searchdir = [];
options = gaoptimset('PlotFcns',@gaplotpareto,'UseParallel',true,'OutputFcns', @outfun,'PopulationSize',5);
xsol = gamultiobj(FitnessFunction,numberOfVariables,[],[],[],[],lb,[],options);
function stop = outfun(x,optimValues,state)
stop = false;
switch state
case 'init'
hold on
case 'iter'
% Concatenate current point and objective function
% value with history. x must be a row vector.
history.fval = [history.fval; optimValues.fval];
history.x = [history.x; x];
% Concatenate current search direction with
% searchdir.
searchdir = [searchdir;...
optimValues.searchdirection'];
plot(x(1),x(2),'o');
% Label points with iteration number and add title.
% Add .15 to x(1) to separate label from plotted 'o'
text(x(1)+.15,x(2),...
num2str(optimValues.iteration));
title('Sequence of Points Computed by fmincon');
case 'done'
hold off
otherwise
end
end
end
I get the following error:
Error using runfmincon/outfun
Too many output arguments.
Error in gaoutput (line 39)
[state,optnew,changed] = feval(functions{i},options.OutputPlotFcnOptions,state,flag,args{i}{:});
Error in gamultiobjsolve (line 13)
[state,options] = gaoutput(FitnessFcn,options,state,currentState);
Error in gamultiobj (line 274)
[x,fval,exitFlag,output,population,scores] = gamultiobjsolve(FitnessFcn,nvars, ...
Error in runfmincon (line 16)
xsol = gamultiobj(FitnessFunction,numberOfVariables,[],[],[],[],lb,[],options);
It would be great, if someone could help me out
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Accepted Answer
Alan Weiss
on 1 Sep 2016
The genetic algorithm has a different syntax for output functions than Optimization Toolbox functions. The syntax is described here. After you correct your syntax things will most likely work (I didn't check in detail, but everything else looks reasonable).
Alan Weiss
MATLAB mathematical toolbox documentation
9 Comments
Alan Weiss
on 2 Sep 2016
You can get the entire population at each iteration from the state.Population field. You can then get the fitness function values by evaluating the fitness functions on the population. There is no other way, as I already told you: "If you want the fitness function of the population, I think that you need to calculate it yourself."
Alan Weiss
MATLAB mathematical toolbox documentation
More Answers (2)
Modess Seyednezhad
on 31 May 2020
Edited: Modess Seyednezhad
on 31 May 2020
Hi,
I have the same issue. The syntaxt page was not useful for me. I could not find my error.
function [history,searchdir] = runmultiobjfunc
% Set up shared variables with OUTFUN
history.x = [];
history.fval = [];
searchdir = [];
% call optimization
nvar = 2;
Lb = [1, 3];
Ub = [19.2, 6.27];
options = optimoptions(@gamultiobj,'OutputFcn',@outfun,...
'Display','iter', 'MaxGenerations',200,'PopulationSize',50);
xsol = gamultiobj(@objfun,nvar,[],[],[],[],Lb,Ub,options);
% Set up output function
function stop = outfun(x,optimValues,state)
stop = false;
switch state
case 'init'
hold on
case 'iter'
% Concatenate current point and objective function
% value with history. x must be a row vector.
history.fval = [history.fval; optimValues.fval];
history.x = [history.x; x];
% Concatenate current search direction with searchdir.
searchdir = [searchdir;...
optimValues.searchdirection'];
plot(x(1),x(2),'o');
% Label points with iteration number and add title.
% Add .15 to x(1) to separate label from plotted 'o'
text(x(1)+.15,x(2),...
num2str(optimValues.iteration));
title('Sequence of Points Computed by gamultiobj');
case 'done'
hold off
otherwise
end
end
end
The error is:
Error using runmultiobjfunc/outfun
Too many output arguments.
Error in gaoutput (line 39)
[state,optnew,changed] = feval(functions{i},options.OutputPlotFcnOptions,state,flag,args{i}{:});
Error in gamultiobjsolve (line 13)
[state,options] = gaoutput(FitnessFcn,options,state,currentState);
Error in gamultiobj (line 303)
[x,fval,exitFlag,output,population,scores] = gamultiobjsolve(FitnessFcn,nvars, ...
Error in runmultiobjfunc (line 15)
xsol = gamultiobj(@objfun,nvar,[],[],[],[],Lb,Ub,options);
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