mutation.m

来自「遗传算法源码,在matlab环境下做的,可以仿真 简单的遗传运算」· M 代码 · 共 66 行

function Ret=Mutation(PMutation,LenChrom,Individuals,SizePop,Opts,Bound,Pop)
% In this function,it fulfils a mutation among chromosomes
% PMutation input  : probability of mutation
% LenChrom  input  : length of a chromosome
% Individuals.Chrom     input  : set of all chromosomes
% SizePop   input  : size of population
% Opts      input  : tag for choosing method of crossover
% Pop       input  : current serial number of generation and maximum gemeration
% Ret       output : new set of chromosome
switch Opts 
    case 'simple' % mutation at single position
            for i=1:SizePop
                % select child at random
                Pick=rand;
                while Pick==0
                    Pick=rand;
                end
                Index=ceil(Pick*SizePop);
                Pick=rand;
                if Pick>PMutation
                   continue;
                end
                % mutation position
                Pick=rand;
                while Pick==0
                     Pick=rand;
                end
                Pos=ceil(Pick*sum(LenChrom));
                v=bitget(Individuals.Chrom(Index),Pos);
                v=~v;
                Chrom1=bitset(Individuals.Chrom(Index),Pos,v);
            end
            
        Ret=Individuals.Chrom;
    case 'float'  % multiple position mutation
        for i=1:SizePop
               % select child at random
                Pick=rand;
                while Pick==0
                    Pick=rand;
                end
                Index=ceil(Pick*SizePop);
                Pick=rand;
                if Pick>PMutation
                   continue;
                end
                % mutation position
                Pick=rand;
                while Pick==0
                     Pick=rand;
                end
                Pos=ceil(Pick*sum(LenChrom));
                v=Individuals.Chrom(i,Pos);
                v1=v-Bound(Pos,1);
                v2=Bound(Pos,2)-v;
                Pick=rand;
                if Pick>0.5
                    Delta=v2*(1-Pick^((1-Pop(1)/Pop(2))^2));
                    Individuals.Chrom(i,Pos)=v+Delta;
                else
                    Delta=v1*(1-Pick^((1-Pop(1)/Pop(2))^2));
                    Individuals.Chrom(i,Pos)=v-Delta;
                end
        end
        Ret=Individuals.Chrom;
end