Multiple input and multiple output | Matlab implements GWO-BP gray wolf algorithm to optimize BP neural network multiple input and multiple output prediction

Multiple input and multiple output | Matlab implements GWO-BP gray wolf algorithm to optimize BP neural network multiple input and multiple output prediction

Prediction effect

basic introduction

Multiple input and multiple output | Matlab implements GWO-BP gray wolf algorithm to optimize BP neural network multiple input and multiple output prediction
1.data is a data set with 10 input features and 3 output variables.
2.main.m is the main program file.
3. The command window outputs MBE, MAE and R2, and the data and program content can be obtained in the download area.

programming

• Complete program and data download method: Private message the blogger to reply to Matlab to implement GWO-BP gray wolf algorithm to optimize BP neural network multi-input multi-output prediction .

function [Alpha_score,Alpha_pos,Convergence_curve]=GWO(SearchAgents_no,Max_iteration,lb,ub,dim,fobj)

%%  优化算法初始化
Alpha_pos = zeros(1, dim);  % 初始化Alpha狼的位置
Alpha_score = inf;          % 初始化Alpha狼的目标函数值,将其更改为-inf以解决最大化问题

Beta_pos = zeros(1, dim);   % 初始化Beta狼的位置
Beta_score = inf;           % 初始化Beta狼的目标函数值 ,将其更改为-inf以解决最大化问题

Delta_pos = zeros(1, dim);  % 初始化Delta狼的位置
Delta_score = inf;          % 初始化Delta狼的目标函数值,将其更改为-inf以解决最大化问题

%%  初始化搜索狼群的位置
Positions = initialization(SearchAgents_no, dim, ub, lb);

%%  用于记录迭代曲线
Convergence_curve = zeros(1, Max_iteration);
%%  循环计数器
iter = 0;

%%  优化算法主循环
while iter < Max_iteration           % 对迭代次数循环
    for i = 1 : size(Positions, 1)   % 遍历每个狼

        % 返回超出搜索空间边界的搜索狼群
        % 若搜索位置超过了搜索空间，需要重新回到搜索空间
        Flag4ub = Positions(i, :) > ub;
        Flag4lb = Positions(i, :) < lb;

        % 若狼的位置在最大值和最小值之间，则位置不需要调整，若超出最大值，最回到最大值边界
        % 若超出最小值，最回答最小值边界
        Positions(i, :) = (Positions(i, :) .* (~(Flag4ub + Flag4lb))) + ub .* Flag4ub + lb .* Flag4lb;   

        % 计算适应度函数值
%         Positions(i, 2) = round(Positions(i, 2));
%         fitness = fical(Positions(i, :));
          fitness = fobj(Positions(i, :));
        % 更新 Alpha, Beta, Delta
        if fitness < Alpha_score           % 如果目标函数值小于Alpha狼的目标函数值
            Alpha_score = fitness;         % 则将Alpha狼的目标函数值更新为最优目标函数值
            Alpha_pos = Positions(i, :);   % 同时将Alpha狼的位置更新为最优位置
        end

        if fitness > Alpha_score && fitness < Beta_score   % 如果目标函数值介于于Alpha狼和Beta狼的目标函数值之间
            Beta_score = fitness;                          % 则将Beta狼的目标函数值更新为最优目标函数值
            Beta_pos = Positions(i, :);                    % 同时更新Beta狼的位置
        end

        if fitness > Alpha_score && fitness > Beta_score && fitness < Delta_score  % 如果目标函数值介于于Beta狼和Delta狼的目标函数值之间
            Delta_score = fitness;                                                 % 则将Delta狼的目标函数值更新为最优目标函数值
            Delta_pos = Positions(i, :);                                           % 同时更新Delta狼的位置
        end

    end

    % 线性权重递减
    wa = 2 - iter * ((2) / Max_iteration);    

    % 更新搜索狼群的位置
    for i = 1 : size(Positions, 1)      % 遍历每个狼
        for j = 1 : size(Positions, 2)  % 遍历每个维度

            % 包围猎物，位置更新
            r1 = rand; % r1 is a random number in [0,1]
            r2 = rand; % r2 is a random number in [0,1]

            A1 = 2 * wa * r1 - wa;   % 计算系数A，Equation (3.3)
            C1 = 2 * r2;             % 计算系数C，Equation (3.4)

            % Alpha 位置更新
            D_alpha = abs(C1 * Alpha_pos(j) - Positions(i, j));   % Equation (3.5)-part 1
            X1 = Alpha_pos(j) - A1 * D_alpha;                     % Equation (3.6)-part 1

            r1 = rand; % r1 is a random number in [0,1]
            r2 = rand; % r2 is a random number in [0,1]

            A2 = 2 * wa * r1 - wa;   % 计算系数A，Equation (3.3)
            C2 = 2 *r2;              % 计算系数C，Equation (3.4)

            % Beta 位置更新
            D_beta = abs(C2 * Beta_pos(j) - Positions(i, j));    % Equation (3.5)-part 2
            X2 = Beta_pos(j) - A2 * D_beta;                      % Equation (3.6)-part 2       

            r1 = rand;  % r1 is a random number in [0,1]
            r2 = rand;  % r2 is a random number in [0,1]

            A3 = 2 *wa * r1 - wa;     % 计算系数A，Equation (3.3)
            C3 = 2 *r2;               % 计算系数C，Equation (3.4)

            % Delta 位置更新
            D_delta = abs(C3 * Delta_pos(j) - Positions(i, j));   % Equation (3.5)-part 3
            X3 = Delta_pos(j) - A3 * D_delta;                     % Equation (3.5)-part 3

            % 位置更新
            Positions(i, j) = (X1 + X2 + X3) / 3;                 % Equation (3.7)

        end
    end

    % 更新迭代器
    iter = iter + 1;    
    Convergence_curve(iter) = Alpha_score;
    disp(['第',num2str(iter),'次迭代'])
    disp(['current iteration is: ',num2str(iter), ', best fitness is: ', num2str(Alpha_score)]);
end

%%  记录最佳参数
% best_lr = Alpha_pos(1, 1);
% best_hd = Alpha_pos(1, 2);
% best_l2 = Alpha_pos(1, 3);
end

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References

[1] https://blog.csdn.net/kjm13182345320/article/details/116377961
[2] https://blog.csdn.net/kjm13182345320/article/details/127931217
[3] https://blog.csdn.net/kjm13182345320/article/details/127894261