sga_selection.m

多种群的链式智能体遗传算法

% 选择复制
% 选择或复制操作是决定哪些个体可以进入下一代。程序中采用赌轮盘选择法选择，这种方法较易实现。
% 根据方程 pi=fi/∑fi=fi/fsum ，选择步骤：
% 1）在第 t 代，由（1）式计算 fsum 和 pi 
% 2）产生 {0,1} 的随机数 rand( .)，求 s=rand( .)*fsum
% 3）求 ∑fi≥s 中最小的 k ，则第 k 个个体被选中
% 4）进行 N 次2）、3）操作，得到 N 个个体，成为第 t=t+1 代种群
%遗传算法子程序
%Name: selection.m
%选择复制
function [newpop]=sga_selection(popsize,pop,fitvalue)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%调试用语句
% popsize=10;
% pop=[1023,980,2133,726,1946,657,1702,1224,1522,807;
%      2025,2565,1773,2340,2354,1144,2061,240,1573,825]
% fitvalue=[96.3814,229.8687,20.4580,142.9572,24.9700,2.2584,34.3755,71.0670,9.2961,9.4407]
% 
% 
% newpop=[1023,1023,1023,980,980,726,726,1702,1702,1224;
%          2025,2025,2025,2565,2565,2340,2340,2061,2061,240];
% dna_best =[980;2565];
% dna_best_value =229.8687;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% row=1;
% dna_best=pop(:,1);
% dna_best_value=fitvalue(1);
% while row<=popsize
%     if dna_best_value<=fitvalue(row)
%         dna_best=pop(:,row);
%         dna_best_value=fitvalue(row);
%     end
%     row=row+1;
% end
% 
% dna_best;
% dna_best_value;


totalfit=sum(fitvalue);%求适应值之和
%  totalfit
fitvalue=fitvalue/totalfit;%单个个体被选择的概率
%  fitvalue
fitvalue=cumsum(fitvalue); %如 fitvalue=[1 2 3 4]，则 cumsum(fitvalue)=[1 3 6 10] 
%  fitvalue
ms=sort(rand(popsize,1)); %从小到大排列，将"rand(px,1)"产生的一列随机数变成轮盘赌形式的表示方法，由小到大排列
%  ms
fitin=1;  %fivalue是一向量，fitin代表向量中元素位，即fitvalue(fitin)代表第fitin个个体的单个个体被选择的概率
newin=1;  %同理
while newin<=popsize;
    
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%    
if ms(newin)<fitvalue(fitin)         %ms(newin)表示的是ms列向量中第"newin"位数值，同理fitvalue(fitin)
newpop(:,newin)=pop(:,fitin);      %赋值 ,即将旧种群中 的第fitin个个体保留到下一代(newpop)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  newpop
%  newin
newin=newin+1;
else
%  fitin
fitin=fitin+1;
end
end
 newpop;