1 简介
传统蝗虫优化算法在处理优化问题时依然存在收敛速度慢,易陷入局部最优的不足.为此,提出了融合混沌映射和柯西变异机制的非线性蝗虫优化算法CCGOA.通过融合混沌Tent映射与反向学习机制,对种群初始化,在确保初始种群质量较优前提下,使种群尽可能均匀分布于搜索空间;利用余弦函数设计非线性自适应系数更新机制,更好均衡个体全局搜索与局部开发能力;引入柯西变异对当前最优个体进行变异扰动,避免算法陷入局部最优.通过基准函数寻优测试,证实提出的算法可以有效提升寻优精度和收敛速度.设计了特征选择算法CCGOA-FS并应用于特征选择问题求解.通过若干数据集测试,证实该算法可以有效进行最优特征子集选取,提升数据分类准确率.
2 部分代码
%_________________________________________________________________________%
% Grasshopper Optimization Algorithm (GOA) source codes demo V1.0 %
% %
%_________________________________________________________________________%
% The Grasshopper Optimization Algorithm
function [TargetFitness,TargetPosition,Convergence_curve,Trajectories,fitness_history, position_history]=GOA(N, Max_iter, lb,ub, dim, fobj)
tic
disp('GOA is now estimating the global optimum for your problem....')
flag=0;
if size(ub,1)==1
ub=ones(dim,1)*ub;
lb=ones(dim,1)*lb;
end
if (rem(dim,2)~=0) % this algorithm should be run with a even number of variables. This line is to handle odd number of variables
dim = dim+1;
ub = [ub; 100];
lb = [lb; -100];
flag=1;
end
%Initialize the population of grasshoppers
GrassHopperPositions=initialization(N,dim,ub,lb);
GrassHopperFitness = zeros(1,N);
fitness_history=zeros(N,Max_iter);
position_history=zeros(N,Max_iter,dim);
Convergence_curve=zeros(1,Max_iter);
Trajectories=zeros(N,Max_iter);
cMax=1;
cMin=0.00004;
%Calculate the fitness of initial grasshoppers
for i=1:size(GrassHopperPositions,1)
if flag == 1
GrassHopperFitness(1,i)=fobj(GrassHopperPositions(i,1:end-1));
else
GrassHopperFitness(1,i)=fobj(GrassHopperPositions(i,:));
end
fitness_history(i,1)=GrassHopperFitness(1,i);
position_history(i,1,:)=GrassHopperPositions(i,:);
Trajectories(:,1)=GrassHopperPositions(:,1);
end
[sorted_fitness,sorted_indexes]=sort(GrassHopperFitness);
% Find the best grasshopper (target) in the first population
for newindex=1:N
Sorted_grasshopper(newindex,:)=GrassHopperPositions(sorted_indexes(newindex),:);
end
TargetPosition=Sorted_grasshopper(1,:);
TargetFitness=sorted_fitness(1);
% Main loop
l=2; % Start from the second iteration since the first iteration was dedicated to calculating the fitness of antlions
while l<Max_iter+1
c=cMax-l*((cMax-cMin)/Max_iter); % Eq. (2.8) in the paper
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:size(GrassHopperPositions,1)
temp= GrassHopperPositions';
% for k=1:2:dim
S_i=zeros(dim,1);
for j=1:N
if i~=j
Dist=distance(temp(:,j), temp(:,i)); % Calculate the distance between two grasshoppers
r_ij_vec=(temp(:,j)-temp(:,i))/(Dist+eps); % xj-xi/dij in Eq. (2.7)
xj_xi=2+rem(Dist,2); % |xjd - xid| in Eq. (2.7)
s_ij=((ub - lb)*c/2)*S_func(xj_xi).*r_ij_vec; % The first part inside the big bracket in Eq. (2.7)
S_i=S_i+s_ij;
end
end
S_i_total = S_i;
% end
X_new = c * S_i_total'+ (TargetPosition); % Eq. (2.7) in the paper
GrassHopperPositions_temp(i,:)=X_new';
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% GrassHopperPositions
GrassHopperPositions=GrassHopperPositions_temp;
for i=1:size(GrassHopperPositions,1)
% Relocate grasshoppers that go outside the search space
Tp=GrassHopperPositions(i,:)>ub';Tm=GrassHopperPositions(i,:)<lb';GrassHopperPositions(i,:)=(GrassHopperPositions(i,:).*(~(Tp+Tm)))+ub'.*Tp+lb'.*Tm;
% Calculating the objective values for all grasshoppers
if flag == 1
GrassHopperFitness(1,i)=fobj(GrassHopperPositions(i,1:end-1));
else
GrassHopperFitness(1,i)=fobj(GrassHopperPositions(i,:));
end
fitness_history(i,l)=GrassHopperFitness(1,i);
position_history(i,l,:)=GrassHopperPositions(i,:);
Trajectories(:,l)=GrassHopperPositions(:,1);
% Update the target
if GrassHopperFitness(1,i)<TargetFitness
TargetPosition=GrassHopperPositions(i,:);
TargetFitness=GrassHopperFitness(1,i);
end
end
Convergence_curve(l)=TargetFitness;
disp(['In iteration #', num2str(l), ' , target''s objective = ', num2str(TargetFitness)])
l = l + 1;
end
if (flag==1)
TargetPosition = TargetPosition(1:dim-1);
end
time=toc
3 仿真结果
4 参考文献
[1]兰娅勋. 混沌和柯西变异的蝗虫优化算法及特征选择[J]. 微电子学与计算机, 2021, 38(11):10.
博主简介：擅长智能优化算法、神经网络预测、信号处理、元胞自动机、图像处理、路径规划、无人机等多种领域的Matlab仿真，相关matlab代码问题可私信交流。
部分理论引用网络文献，若有侵权联系博主删除。
