遗传算法matlab实现

我是小鸭酱，博客地址为：http://www.cnblogs.com/xiaoyajiang

以下运用MATLAB实现遗传算法：

clc

clear

%参数

a = 0 ;

b = 4 ;

eps = 0.01 ;

lenchrom = ceil(log2((b - a)/eps + 1)) ;

sizepop = 50 ;

maxgen = 500 ;

pcross = 0.9 ;

pm = 0.05 ;

fitness = ones(1,sizepop) ;

chrom = zeros(sizepop,lenchrom) ;

nx = zeros(sizepop,lenchrom) ;

%初始化

%随机产生一个种群

for i = 1 : sizepop

for j = 1 : lenchrom

chrom(i,j) = round(rand) ;

end

x = a + (b - a) * (dot( 2 .^ ((lenchrom - 1) : -1 : 0 ) , chrom(i,:)) ) / ( 2 ^ lenchrom - 1) ;

fitness(i) = fun(x);

end

[bestfitness , bestindex] = max(fitness);

bestchrom = chrom(bestindex,:) ;

for i = 1 : maxgen

%select

sumfitness = sum(fitness) ;

fit = fitness ./ sumfitness ;

tfit = zeros(sizepop) ;

tfit(1) = fit(1) ;

for j = 2 : sizepop

tfit(j) = tfit(j - 1) + fit(j) ;

end

for k = 1 : sizepop

pick = rand ;

if pick < fit(1)

father = 1 ;

else

for l = 1 : (sizepop - 1 )

if pick > tfit(l) && pick < tfit(l + 1)

father = l + 1 ;

end

end

end

mother = ceil(rand * sizepop) ;

%cross

pick = rand ;

if pcross > pick

poscross = randperm(lenchrom,1) ;

nx(k,1:poscross) = chrom(father,1:poscross) ;

nx(k,(poscross + 1):lenchrom) = chrom(mother,(poscross + 1):lenchrom) ;

else

nx(k,:) = chrom(father,:) ;

end

%mutation

index = randperm(sizepop,1) ;

pick = rand ;

if pick < pm

posm = randperm(lenchrom,1) ;

chrom(index,posm) = ~chrom(index,posm) ;

end

end

chrom = nx ;

for j = 1 : sizepop

x = a + (b - a) * (dot( 2 .^ ((lenchrom - 1) : -1 : 0 ) , chrom(j,:)) ) / ( 2 ^ lenchrom - 1) ;

fitness(j) = fun(x) ;

end

[newbestfitness , newbestindex] = max(fitness) ;

if newbestfitness > bestfitness

bestfitness = newbestfitness ;

bestindex = newbestindex ;

bestchorm = chrom(bestindex,:) ;

end

end

bestx = a + (b - a) * (dot( 2 .^ ((lenchrom - 1) : -1 : 0 ) , bestchrom) ) / ( 2 ^ lenchrom - 1)

bestf = bestx * sin(bestx)