cluster_cost.m

clustering_code ,Clustering Through Ranking On Manifolds Version 0.2 Copyright by Markus Breit

function [cost_cc,clus_close,cc_on,cc_off,Y] = Cluster_Cost(F,dot_dist,num_classes,n,OPT)

%
% Clustering Through Ranking On Manifolds
% Version 0.2
%
% Copyright by Markus Breitenbach and Gregory Z. Grudic
% This code is for your personal and research use only.
%
% http://www.cs.colorado.edu/~grudic/
% http://ucsu.colorado.edu/~breitenm/
%
% This software is provided "as is," without warranty of any kind, express
% or implied.  In no event shall the authors be held liable
% for any direct, indirect, incidental, special or consequential damages
% arising out of the use of or inability to use this software.
%

% assign all n examples to a class
Y = zeros(n,num_classes);
for i=1:n
    ind_t = find(max(F(i,:)) == F(i,:));
    Y(i,ind_t) = 1;
end

tot_num = n*n;

clus_close = zeros(num_classes,num_classes);
clus_count = zeros(num_classes,1);

% within cluster
for i = 1:num_classes
    ind_t = logical(Y(:,i));
    tmp_d_m = dot_dist(ind_t,ind_t); % all dot_dist values of our class
    [nt,mt] = size(tmp_d_m);
	if nt==0
		clus_close(i,i) = 0;
	else
	    off_diag_ind = find(eye(nt,nt)==0);
	    on_diag_ind = find(eye(nt,nt)==1);
	    clus_count(i) = length(on_diag_ind);
	    if isempty(off_diag_ind)
	        clus_close(i,i) = 0;
	    else
	        clus_close(i,i) = mean(tmp_d_m(off_diag_ind));
	    end
	end;
end

%outside clusters
for i = 2:num_classes
    for j = 1:i
        ind_ti = logical(Y(:,i));
        ind_tj = logical(Y(:,j));
        tmp_d_m = dot_dist(ind_ti,ind_tj);
        if isempty(tmp_d_m)
            clus_close(i,j) = 0;
            clus_close(j,i) = 0;
        else
            [nt,mt] = size(tmp_d_m);
            %off_diag_ind = find(eye(nt,nt)==0);
            clus_close(i,j) = mean(tmp_d_m(:));
            clus_close(j,i) = clus_close(i,j);
        end
    end
end


ind_off_diag = find(eye(num_classes,num_classes)==0);
ind_on_diag = find(eye(num_classes,num_classes)==1);

cc_off = mean(clus_close(ind_off_diag));
cc_on = mean(clus_close(ind_on_diag));

if OPT == 1
    cost_cc = cc_off-cc_on;
else
    return;
end