select_roulette.m

来自「人工免疫算法基于遗传MATLAB代码很有用哦」· M 代码 · 共 35 行

function[newPop] = select_Roulette(oldPop)
% 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]

% Binary and Real-Valued Simulation Evolution for Matlab 
% Copyright (C) 1996 C.R. Houck, J.A. Joines, M.G. Kay 
%

% Get the parameters of the population
numVars = size(oldPop,2);  % 列
numSols = size(oldPop,1);  % 行

% 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