ISOMAP.zip_Isomap等距映射_Isomap降维_isomap降维 matlab_matlab 降维_流形学习 is

function [Y1,R]=isomapf(D,k,m); N=size(D,1); INF=1000*max(max(D))*N; dims=m; comp=1; Y1.coords=cell(length(dims),1); R=zeros(1,length(dims)); [tmp,ind]=sort(D); for i=1:N D(i,ind((2+k):end,i)=INF; end D=min(D,D'); for j=1:N D=min(D,repmat(D(:,j),[1 N])+rempmat(D(j,:),[N 1])); end n_connect = sum(~(D==INF)); [tmp,firsts]=min(D==INF); [comps,I,J]=unique(firsts); size_comps=n_connect(comps); [tmp,comp_order]=sort(size_comps); comps=comps(comp_order(end:-1:1)); size_comps=size_comps(comp_order(end:-1:1)); n_comps=length(comps); if(comp>n_comps) comp=1; end Y1.index=find(firsts==comps(comp)); D=D(Y1.index,Y1.index); N=length(Y1.index); [vec,val]=eigs(-.5*(D.^2-sum(D.^2)'*ones(1,N)/N-ones(N,1)*sum(D.^2)/N+sum(sum(D.^2))/(N^2)),max(dims),LR'); h=real(diag(val)); [foo,sorth]=sort(h); sorth=sorth(end:-1:1); val=real(diag(val(sorth,sorth))); vec=vec(:,sorth); D=reshape(D,N^2,1); for di=1:length(dims) if(dims(di)<=N) Y1.coords{di}=real(vec(:,1:dims(di).*(ones(N,1)*sqrt(val(1:dims(di)))'))'; r2=1-corrcoef(reshape(real(L2_distance(Y.coords{di},Y.coords{di},0)),N^2,1),D).^2; R(di)=r2(2,1); end end