roulette.m

王小平《遗传算法——理论、应用与软件实现》随书光盘

function[newPop] = roulette(oldPop,options)
% roulette is the traditional selection function with the probability of
% surviving equal to the fitness of i / sum of the fitness of all individuals
% function[newPop] = roulette(oldPop,options)
% newPop  - the new population selected from the oldPop
% oldPop  - the current population
% options - options [gen]
% Get the parameters of the population
numVars = size(oldPop,2);
numSols = size(oldPop,1);
% Generate the relative probabilities of selection
totalFit = sum(oldPop(:,numVars));
prob=oldPop(:,numVars) / totalFit; 
prob=cumsum(prob);
rNums=sort(rand(numSols,1)) 		% Generate random numbers
% Select individuals from the oldPop to the new
fitIn=1;newIn=1;
while newIn<=numSols
  if(rNums(newIn)<prob(fitIn))
    newPop(newIn,:) = oldPop(fitIn,:);
    newIn = newIn+1;
  else
    fitIn = fitIn + 1;
  end
end
end