遗传算法matlab程序实例.docx
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遗传算法matlab程序实例
%-----------------------------------------------
%---------------------------------------------------
遗传算法程序
(一):
说明:
fga.m为遗传算法的主程序;采用二进制Gray编码,采用基于轮盘赌法的非线性排名选择,均匀交叉,变异操作,而且还引入了倒位操作!
function[BestPop,Trace]=fga(FUN,LB,UB,eranum,popsize,pCross,pMutation,pInversion,options)
%[BestPop,Trace]=fmaxga(FUN,LB,UB,eranum,popsize,pcross,pmutation)
%Findsamaximumofafunctionofseveralvariables.
%fmaxgasolvesproblemsoftheform:
%maxF(X)subjectto:
LB<=X<=UB
%BestPop-最优的群体即为最优的染色体群
%Trace-最佳染色体所对应的目标函数值
%FUN-目标函数
%LB-自变量下限
%UB-自变量上限
%eranum-种群的代数,取100--1000(默认200)
%popsize-每一代种群的规模;此可取50--200(默认100)
%pcross-交叉概率,一般取0.5--0.85之间较好(默认0.8)
%pmutation-初始变异概率,一般取0.05-0.2之间较好(默认0.1)
%pInversion-倒位概率,一般取0.05-0.3之间较好(默认0.2)
%options-1*2矩阵,options
(1)=0二进制编码(默认0),option
(1)~=0十进制编
%码,option
(2)设定求解精度(默认1e-4)
%
%------------------------------------------------------------------------
T1=clock;
ifnargin<3,error('FMAXGArequiresatleastthreeinputarguments');end
ifnargin==3,eranum=200;popsize=100;pCross=0.8;pMutation=0.1;pInversion=0.15;options=[01e-4];end
ifnargin==4,popsize=100;pCross=0.8;pMutation=0.1;pInversion=0.15;options=[01e-4];end
ifnargin==5,pCross=0.8;pMutation=0.1;pInversion=0.15;options=[01e-4];end
ifnargin==6,pMutation=0.1;pInversion=0.15;options=[01e-4];end
ifnargin==7,pInversion=0.15;options=[01e-4];end
iffind((LB-UB)>0)
error('数据输入错误,请重新输入(LB');
end
s=sprintf('程序运行需要约%.4f秒钟时间,请稍等......',(eranum*popsize/1000));
disp(s);
globalmnNewPopchildren1children2VarNum
bounds=[LB;UB]';bits=[];VarNum=size(bounds,1);
precision=options
(2);%由求解精度确定二进制编码长度
bits=ceil(log2((bounds(:
2)-bounds(:
1))'./precision));%由设定精度划分区间
[Pop]=InitPopGray(popsize,bits);%初始化种群
[m,n]=size(Pop);
NewPop=zeros(m,n);
children1=zeros(1,n);
children2=zeros(1,n);
pm0=pMutation;
BestPop=zeros(eranum,n);%分配初始解空间BestPop,Trace
Trace=zeros(eranum,length(bits)+1);
i=1;
whilei<=eranum
forj=1:
m
value(j)=feval(FUN(1,:
),(b2f(Pop(j,:
),bounds,bits)));%计算适应度
end
[MaxValue,Index]=max(value);
BestPop(i,:
)=Pop(Index,:
);
Trace(i,1)=MaxValue;
Trace(i,(2:
length(bits)+1))=b2f(BestPop(i,:
),bounds,bits);
[selectpop]=NonlinearRankSelect(FUN,Pop,bounds,bits);%非线性排名选择
[CrossOverPop]=CrossOver(selectpop,pCross,round(unidrnd(eranum-i)/eranum));
%采用多点交叉和均匀交叉,且逐步增大均匀交叉的概率
%round(unidrnd(eranum-i)/eranum)
[MutationPop]=Mutation(CrossOverPop,pMutation,VarNum);%变异
[InversionPop]=Inversion(MutationPop,pInversion);%倒位
Pop=InversionPop;%更新
pMutation=pm0+(i^4)*(pCross/3-pm0)/(eranum^4);
%随着种群向前进化,逐步增大变异率至1/2交叉率
p(i)=pMutation;
i=i+1;
end
t=1:
eranum;
plot(t,Trace(:
1)');
title('函数优化的遗传算法');xlabel('进化世代数(eranum)');ylabel('每一代最优适应度(maxfitness)');
[MaxFval,I]=max(Trace(:
1));
X=Trace(I,(2:
length(bits)+1));
holdon;plot(I,MaxFval,'*');
text(I+5,MaxFval,['FMAX='num2str(MaxFval)]);
str1=sprintf('进化到%d代,自变量为%s时,得本次求解的最优值%f\n对应染色体是:
%s',I,num2str(X),MaxFval,num2str(BestPop(I,:
)));
disp(str1);
%figure
(2);plot(t,p);%绘制变异值增大过程
T2=clock;
elapsed_time=T2-T1;
ifelapsed_time(6)<0
elapsed_time(6)=elapsed_time(6)+60;elapsed_time(5)=elapsed_time(5)-1;
end
ifelapsed_time(5)<0
elapsed_time(5)=elapsed_time(5)+60;elapsed_time(4)=elapsed_time(4)-1;
end%像这种程序当然不考虑运行上小时啦
str2=sprintf('程序运行耗时%d小时%d分钟%.4f秒',elapsed_time(4),elapsed_time(5),elapsed_time(6));
disp(str2);
%初始化种群
%采用二进制Gray编码,其目的是为了克服二进制编码的Hamming悬崖缺点
function[initpop]=InitPopGray(popsize,bits)
len=sum(bits);
initpop=zeros(popsize,len);%Thewholezeroencodingindividual
fori=2:
popsize-1
pop=round(rand(1,len));
pop=mod(([0pop]+[pop0]),2);
%i=1时,b
(1)=a
(1);i>1时,b(i)=mod(a(i-1)+a(i),2)
%其中原二进制串:
a
(1)a
(2)...a(n),Gray串:
b
(1)b
(2)...b(n)
initpop(i,:
)=pop(1:
end-1);
end
initpop(popsize,:
)=ones(1,len);%Thewholeoneencodingindividual
%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%解码
function[fval]=b2f(bval,bounds,bits)
%fval-表征各变量的十进制数
%bval-表征各变量的二进制编码串
%bounds-各变量的取值范围
%bits-各变量的二进制编码长度
scale=(bounds(:
2)-bounds(:
1))'./(2.^bits-1);%Therangeofthevariables
numV=size(bounds,1);
cs=[0cumsum(bits)];
fori=1:
numV
a=bval((cs(i)+1):
cs(i+1));
fval(i)=sum(2.^(size(a,2)-1:
-1:
0).*a)*scale(i)+bounds(i,1);
end
%选择操作
%采用基于轮盘赌法的非线性排名选择
%各个体成员按适应值从大到小分配选择概率:
%P(i)=(q/1-(1-q)^n)*(1-q)^i,其中P(0)>P
(1)>...>P(n),sum(P(i))=1
function[selectpop]=NonlinearRankSelect(FUN,pop,bounds,bits)
globalmn
selectpop=zeros(m,n);
fit=zeros(m,1);
fori=1:
m
fit(i)=feval(FUN(1,:
),(b2f(pop(i,:
),bounds,bits)));%以函数值为适应值做排名依据
end
selectprob=fit/sum(fit);%计算各个体相对适应度(0,1)
q=max(selectprob);%选择最优的概率
x=zeros(m,2);
x(:
1)=[m:
-1:
1]';
[yx(:
2)]=sort(selectprob);
r=q/(1-(1-q)^m);%标准分布基值
newfit(x(:
2))=r*(1-q).^(x(:
1)-1);%生成选择概率
newfit=cumsum(newfit);%计算各选择概率之和
rNums=sort(rand(m,1));
fitIn=1;newIn=1;
whilenewIn<=m
ifrNum