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本帖最后由 thinkfunny 于 2020-10-22 15:41 编辑
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3 x! [: E1 J0 e9 p3 E9 ~这一篇是Xue Bing在一区cybernetics发的论文,里面提出了两个多目标PSO特征选择算法,一个是NSPSO另一个是CMDPSO。其中NSPSO是参考了NSGA2的框架和思想。! }8 C" b3 g1 X+ Q
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具体流程0 h/ m+ r5 n& i' z4 D3 C/ i0 {% a
- ①划分数据集为测试集和训练集
- ②初始化PSO算法
- ③迭代开始
- ④计算两个目标值(论文中是特征数和错误率)
- ⑤非支配排序
- ⑥拥挤距离度量并排序
- ⑥对每个粒子从第一前沿面选择一个粒子作为gbest,更新当前粒子
- ⑦调整粒子群
- ⑧迭代结束返回+ ]7 ]* F9 x5 s# n, f
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MATLAB实现:
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注意其中FSKNN是我的问题的评价函数,包含两个目标值,都存入到pfitness中
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3 i3 ?9 ? ^' V, f) w- function [solution,time,pop,pfitness,site,LeaderAVE] = NSPSO(train_F,train_L)
- tic
- global maxFES
- dim = size(train_F,2);
- FES = 1;
- sizep = 30;
- pop = rand(sizep,dim);
- popv = rand(sizep,dim);
- pfitness = zeros(sizep,2);
- LeaderAVE = zeros(1,2);
- while FES <maxFES
- Off_P = zeros(sizep,dim);
- Off_V = zeros(sizep,dim);
- ofitness = zeros(sizep,2);
- for i=1:sizep
- [pfitness(i,1),pfitness(i,2)] = FSKNN(pop(i,: ),i,train_F,train_L);
- end
- Front = NDSort(pfitness(:,1:2),sizep);
- [~,rank] = sortrows([Front',-CrowdingDistance(pfitness,Front)']);
- LeaderSet = rank(1:10);
- solution = pfitness(LeaderSet,: );
- LeaderAVE(1) = mean(solution(:,1));
- LeaderAVE(2) = mean(solution(:,2));
- for i = 1:sizep
- good = LeaderSet(randperm(length(LeaderSet),1));
- r1 = rand(1,dim);
- r2 = rand(1,dim);
- Off_V(i,: ) = r1.*popv(i,: ) + r2.*(pop(good,: )-pop(i,: ));
- Off_P(i,: ) = pop(i,: ) + Off_V(i,: );
- end
- for i=1:sizep
- [ofitness(i,1),ofitness(i,2)] = FSKNN(Off_P(i,: ),i,train_F,train_L);
- end
- temppop = [pop;Off_P];
- tempv = [popv;Off_V];
- tempfiness = [pfitness;ofitness];
- [FrontNO,MaxFNO] = NDSort(tempfiness(:,1:2),sizep);
- Next = false(1,length(FrontNO));
- Next(FrontNO<MaxFNO) = true;
- PopObj = tempfiness;
- fmax = max(PopObj(FrontNO==1,: ),[],1);
- fmin = min(PopObj(FrontNO==1,: ),[],1);
- PopObj = (PopObj-repmat(fmin,size(PopObj,1),1))./repmat(fmax-fmin,size(PopObj,1),1);
- % Select the solutions in the last front
- Last = find(FrontNO==MaxFNO);
- del = Truncation(PopObj(Last,: ),length(Last)-sizep+sum(Next));
- Next(Last(~del)) = true;
- % Population for next generation
- pop = temppop(Next,: );
- popv = tempv(Next,: );
- pfitness = tempfiness(Next,: );
- fprintf('GEN: %2d Error: %.4f F:%.2f\n',FES,LeaderAVE(1),LeaderAVE(2));
- FES = FES + 1;
- end
- [FrontNO,~] = NDSort(pfitness(:,1:2),sizep);
- site = find(FrontNO==1);
- solution = pfitness(site,: );
- LeaderAVE(1) = mean(solution(:,1));
- LeaderAVE(2) = mean(solution(:,2));
- toc
- time = toc;
- end" Q9 M( p. d+ V+ C* G6 y4 i
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5 W2 a# d. X4 f; T9 s+ J拥挤距离代码:
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$ B# z0 c" U3 B6 m/ R- function CrowdDis = CrowdingDistance(PopObj,FrontNO)
- % Calculate the crowding distance of each solution front by front
- % Copyright 2015-2016 Ye Tian
- [N,M] = size(PopObj);
- CrowdDis = zeros(1,N);
- Fronts = setdiff(unique(FrontNO),inf);
- for f = 1 : length(Fronts)
- Front = find(FrontNO==Fronts(f));
- Fmax = max(PopObj(Front,: ),[],1);
- Fmin = min(PopObj(Front,: ),[],1);
- for i = 1 : M
- [~,Rank] = sortrows(PopObj(Front,i));
- CrowdDis(Front(Rank(1))) = inf;
- CrowdDis(Front(Rank(end))) = inf;
- for j = 2 : length(Front)-1
- CrowdDis(Front(Rank(j))) = CrowdDis(Front(Rank(j)))+(PopObj(Front(Rank(j+1)),i)-PopObj(Front(Rank(j-1)),i))/(Fmax(i)-Fmin(i));
- end
- end
- end
- end
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Truncation.m代码:
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- function Del = Truncation(PopObj,K)
- % Select part of the solutions by truncation
- N = size(PopObj,1);
- %% Truncation
- Distance = pdist2(PopObj,PopObj);
- Distance(logical(eye(length(Distance)))) = inf;
- Del = false(1,N);
- while sum(Del) < K
- Remain = find(~Del);
- Temp = sort(Distance(Remain,Remain),2);
- [~,Rank] = sortrows(Temp);
- Del(Remain(Rank(1))) = true;
- end
- end
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