人工水母搜索算法—matlab代码

Posted 2021-05-29 编码雪人

clc
clear
foj = @ Sphere;
Lb = -100;  % 搜索空间下界
Ub = 100;   % 搜索空间上界

N_iter = 1000;  % 最大迭代次数
n_pop = 50;  % 种群个数
d = 10; % 种群维度
beta = 3;
gamma = 0.1;
Z = zeros(n_pop, d);

% 随机生成一个d维向量
Z(1, :) = rand(1, d);

% 利用logistic生成n_pop个向量
for i=2:n_pop
    Z(i,:) = 4.0*Z(i-1,:).*(1-Z(i-1,:));
end

% 将z的各个分量载波到对应变量的取值区间
pop = zeros(n_pop, d);
fitness = zeros(n_pop, 1);
for i=1:n_pop
    pop(i,:) = Lb + (Ub - Lb)*Z(i,:);
    fitness(i) = foj(pop(i,:));
end
mu = mean(pop, 1); 
figure 
scatter(pop(:,1), pop(:,2), \'r*\');
hold on
scatter(mu(:,1), mu(:,2),\'ko\');
box on
[bestScore, loc] = min(fitness);
bestPop = pop(loc, :); % 当前种群中食物数目最多的位置
S = pop; % S是更新后的种群
fmin = zeros(N_iter,1);
for t=1:N_iter
    for i=1:n_pop
        c = abs((1-t/N_iter)*(2*rand-1));
        if c>=0.5
            % 洋流位置更新公式
            trend = bestPop - beta*rand*mu; % 洋流的方向,即论文中的公式.9
            S(i,:) = pop(i,:) + rand(1,d).*trend; % 水母位置更新，即论文中的公式.11
        else
            % 种群内部运动
            if rand>(1-c)
                S(i,:) = pop(i,:) + gamma*rand(1,d).*(Ub - Lb); % 被动运动，即论文公式.12
            else
                 JK = randperm(n_pop); 
                 if foj(pop(JK(1)))>=foj(pop(JK(2)))
                     Direction = pop(JK(2),:) - pop(JK(1),:);
                 else
                     Direction = pop(JK(1),:) - pop(JK(2),:);
                 end
                 Step = rand(1, d).*Direction;
                 S(i,:) = pop(i,:) + Step; % 主动运动，论文公式.16
            end
        end
        % 检查边界
        S(i,:) = simpleBound(S(i,:), Lb, Ub);
        Fnew = foj(S(i,:));
        % 判断是否更新相应位置和适应度值
        if Fnew<fitness(i)
            fitness(i) = Fnew;
            pop(i,:) = S(i,:);
        end
        
        % 判断是否更新最优值
        if Fnew<bestScore
            bestScore = Fnew;
            bestPop = S(i,:);
        end
    end
    fmin(t) = bestScore;
    % 命令窗口输出
    disp([\'Iteration \' num2str(t) \': Best Cost = \' num2str(bestScore)]);
%     disp([\'Bestpop \' num2str(bestPop)]);
end
figure
semilogy(fmin, \'r-.\')

　　

function x=simpleBound(x,Lb,Ub)
% 函数名称：越界处理函数
% param x：水母
% param Lb：变量下界
% param Ub：变量上界
    d = length(x);
    for i=1:d
        if x(d) > Ub
            x(d) = (x(d) - Ub) + Lb;
        elseif x(d) < Lb
            x(d) = (x(d) - Lb) + Ub;
        end
    end
end

　　

function [y] = Sphere(xx)
    d = length(xx);
    sum = 0;
    for ii = 1:d
    	xi = xx(ii);
    	sum = sum + xi^2;
    end
    y = sum;
end