maniMethods.m

% dimension reduction function
%
% Dis - L2 distance matrix
% method - string giving method name
% d - output dimension
% K,delta - algorithm parameters

function [Y,index,FVE,Manidis] = maniMethods(Dis,method,d,K,delta)

N = size(Dis,1);
switch lower(method)
    case 'isomap'
        options.dims = 1:10;
        [Y_ISOMAP,FVE] = IsomapII(Dis,'k',K,options);
        Y = Y_ISOMAP.coords{d}';
        index = Y_ISOMAP.index;
        tempt1 = L2_distance(Y',Y');
%         FVE =
%         sqrt(sum(sum((tempt1-Dis(index,index)).^2)))/sqrt(sum(sum(Dis(ind
%         ex,index).^2)));
        clear tempt1 tempt2;
    otherwise
        % initial step: connect K nearest points
        [Sort_dis,Ord] = sort(Dis);
        radius = median(Sort_dis(K+1,:));
        Counts = [];
        Indmat = zeros(N,N);
        for i=1:N
            Counts(i) = sum(Dis(:,i)<=radius)-1;
            Indmat(Ord(1:K+1,i),i)=ones(K+1,1);
        end
        Indmat = (Indmat+Indmat')>=1;
        % fprintf([num2str(sum(Counts<0.5)) ' points have no neighbor. \n ']);
        T1 = quantile(Counts,delta)+1;
        Pen = @(x)((x+1)./T1).^-2.*(x<T1)+1;
        Pval = max(repmat(Pen(Counts)',[1 N]),repmat(Pen(Counts),[N 1]));
        Manipath = Pval.*Dis;
        Manipath(~Indmat) = inf;
        Manidis = Dis;
        Manidis(~Indmat) = inf;
        for k=1:N
            for i=1:N
                for j=1:N
                    if Manipath(i,k)+Manipath(k,j)<Manipath(i,j)
                        Manipath(i,j) = Manipath(i,k)+Manipath(k,j);
                        Manidis(i,j) = Manidis(i,k)+Manidis(k,j);
                    end
                end
            end
        end
        Manidis = (Manidis+Manidis')/2;
        % check unconnected points
        tempid = sum(Manidis==inf);
        if sum(tempid)==0
            % fprintf('All points are connected. \n');
            index = 1:N;
        elseif min(tempid)==sum(tempid==N-1)
            % fprintf([ num2str(min(tempid)) ' points are not connected to others. \n ']);
            index = find(tempid==min(tempid));
            Manidis = Manidis(index,index);
            Manipath = Manipath(index,index);
        else
            index = find(tempid==min(tempid));
            % fprintf(['There are more than one clusterings. The largest clustering with ' num2str(length(index))  ' points is embeded. \n '])
            Manidis = Manidis(index,index);
            Manipath = Manipath(index,index);
        end
        [Y,E] = cmdscale(Manidis);
        Y = Y(:,1:d);
        tempt1 = L2_distance(Y',Y');
        FVE = sqrt(sum(sum((tempt1-Dis(index,index)).^2)))/sqrt(sum(sum(Dis(index,index).^2)));
end

end