select_gen.m

多智能体工具包

function newchrom=select_gen(criteria,chrom)
% SELECT_GEN	Selects best chromosomes for next generation based on the criteria.

%     Copyright (c) 1997-2000 Jiming Liu and Jianbing Wu

global Genetic_Result;

[pop bitlength]=size(chrom);
fit=[];
%calculate fitness
[fit,fitot]=call_fitness(criteria,chrom);  

Genetic_Result=[Genetic_Result;fit];

for chromnum=1:pop
  sval(chromnum)=sum(fit(1,1:chromnum));
end
%select according to fitness by probability

% Remain a most optimal population.
% if change it ,the loop variable should be i=1:pop
[fit_max,Pos]=max(fit);
parname=Pos;

for i=1:pop-1
  rval=fitot*rand;
  if rval<=sval(1)
    parname=[parname 1];
  else
    for j=1:pop-1
      sl=sval(j);    % Left value for comparing
      su=sval(j+1);  % Right value for comparing
      if (rval>sl) & (rval<=su)
         parname=[parname j+1];
         break;
      end
    end
  end	
end
newchrom(1:pop,:)=chrom(parname,:);