MATLAB: No repetition in the result of a roulette wheel selection function

genetic algorithmrandom number generator

Please, I would like to ask someone a little question: what should I do if I have to write a roulette selection function for a genetic algorithm in which the resulting numbers have no repetition. In example, if I write the selectionroulette of matlab toolbox:
 function parents = selection3roulette(expectation,nParents,options)
 % example
 nParents=14;    
 expectation=[1.6098;
    0.9294;
    1.1383;
    1.9716;
    1.3941;
    1.2470;
    0.9858;
    0.8817;
    1.0539;
    2.7883];
 expectation = expectation(:,1);
 wheel = cumsum(expectation) / nParents;
 parents = zeros(1,nParents);
 for i = 1:nParents
    r = rand;
    for j = 1:length(wheel)
        if(r < wheel(j))
            parents(i) = j;
            break;
        end
    end
 end
 disp('parents=');disp(parents);
at the end I could obtain : parents= [5 5 1 5 7 6 2 7 5 8 1 5 3 8] instead I wolud have different elements into the array… Thank you very much….

Best Answer

doc randperm
maybe?
Related Question