mutation.m

本程序模拟GP算法处理数据的方法步骤How can computers learn to solve problems without being explicitly programmed? In

function y=mutation(n)
ss='';
s=n;
a1=find(s=='+');
ss(a1)='+';
a1=find(s=='-');
ss(a1)='-';
a1=find(s=='*');
ss(a1)='*';
a1=find(s=='/');
ss(a1)='/';
n=ss;
s='+-*/';
a='';
r=ceil(rand*8);
for i=1:r
    a(i)=s(ceil(rand*4));
end
if ceil(rand*2)==1
    if 20-length(n)>r;
        y=strcat(n,a);
    else
        for i=1:20-length(n)
        b(i)=a(i);
        end
        y=strcat(n,b);
    end
else
    if length(n)>r
         for i=1:r
             n(length(n))='';
         end
    else
        rn=ceil(rand*length(n));
        if length(n)-rn>1
            for i=1:rn
                n(1)='';
            end
        end
    end    
    y=n;
end