【预测模型】基于Logistic混沌映射改进麻雀算法改进BP神经网络实现数据预测matlab源码

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 1  模型

简介见这里。

2 部分代码

function [FoodFitness,FoodPosition,Convergence_curve]=SSA(N,Max_iter,lb,ub,dim,fobj)
if size(ub,1)==1
    ub=ones(dim,1)*ub;
    lb=ones(dim,1)*lb;
end
Convergence_curve = zeros(1,Max_iter);
%Initialize the positions of salps
SalpPositions=initialization(N,dim,ub,lb);
FoodPosition=zeros(1,dim);
FoodFitness=inf;
%calculate the fitness of initial salps
for i=1:size(SalpPositions,1)
    SalpFitness(1,i)=fobj(SalpPositions(i,:));
end
[sorted_salps_fitness,sorted_indexes]=sort(SalpFitness);
for newindex=1:N
    Sorted_salps(newindex,:)=SalpPositions(sorted_indexes(newindex),:);
end
FoodPosition=Sorted_salps(1,:);
FoodFitness=sorted_salps_fitness(1);
%Main loop
l=2; % start from the second iteration since the first iteration was dedicated to calculating the fitness of salps
while l<Max_iter+1
    c1 = 2*exp(-(4*l/Max_iter)^2); % Eq. (3.2) in the paper
    for i=1:size(SalpPositions,1)
        SalpPositions= SalpPositions';
        if i<=N/2
            for j=1:1:dim
                c2=rand();
                c3=rand();
                %%%%%%%%%%%%% % Eq. (3.1) in the paper %%%%%%%%%%%%%%
                if c3<0.5 
                    SalpPositions(j,i)=FoodPosition(j)+c1*((ub(j)-lb(j))*c2+lb(j));
                else
                    SalpPositions(j,i)=FoodPosition(j)-c1*((ub(j)-lb(j))*c2+lb(j));
                end
                %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
            end
        elseif i>N/2 && i<N+1
            point1=SalpPositions(:,i-1);
            point2=SalpPositions(:,i);
            SalpPositions(:,i)=(point2+point1)/2; % % Eq. (3.4) in the paper
        end
        SalpPositions= SalpPositions';
    end
    for i=1:size(SalpPositions,1)
        Tp=SalpPositions(i,:)>ub';Tm=SalpPositions(i,:)<lb';SalpPositions(i,:)=(SalpPositions(i,:).*(~(Tp+Tm)))+ub'.*Tp+lb'.*Tm;
        SalpFitness(1,i)=fobj(SalpPositions(i,:));
        if SalpFitness(1,i)<FoodFitness
            FoodPosition=SalpPositions(i,:);
            FoodFitness=SalpFitness(1,i); 
        end
    end
    Convergence_curve(l)=FoodFitness;
    l = l + 1;
end

3 仿真结果

4 参考文献

《基于BP神经网络的宁夏水资源需求量预测》

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