dbscan_demo.m

clear all;
clear figure;
ds = [0 0;
      -1 0;
      -1 1;
       1 0;
       1 2;
       2 2;
       0 2;
       2 1;
       4 4;
       5 4;
       6 4;
       7 4;
       4 5;
       5 6;
       6 7;
       6 9;
       8 2;
       -2 6;
       5 5;
      6 8;
	  7 9;
       8 8];

x = ds(:,1);
y = ds(:,2);

L = length(x);

%plot(x,y,'rx','linewidth',2);


d_x = x - x';
d_y = y - y';

% Matriz de distancias
d = sqrt(d_x.^2 + d_y.^2);

% Parametros DBSCAN

eps = 2.3;
minPts = 5;

d_th = (d <= eps).*not(eye(L));

np = sum(d_th);

labels = -1*ones(L,1);
visited = zeros(L,1);

c_id = 0;



for i=1:L
	if (visited(i) == 0)
		visited(i) = 1;
		
		eps_neigs = find(d_th(:,i));

		if(np(i) < minPts)
			labels(i) = 0;
		else
			c_id++
			labels(i) = c_id;
			
			j = 1;
			while j<=length(eps_neigs)
				if (visited(eps_neigs(j)) == 0)
					visited(eps_neigs(j)) = 1;
%					printf("j: %d\n",eps_neigs(j) );
					eps_neigs_2 = find(d_th(:,eps_neigs(j)));
					
					if(np(eps_neigs(j)) >= minPts)
						%eps_neigs
						eps_neigs = unique([eps_neigs;eps_neigs_2]);
					end

				end
				if (labels(eps_neigs(j)) == -1 || labels(eps_neigs(j)) == 0)
					labels(eps_neigs(j)) = c_id;
					j = 1;				
				elseif (labels(eps_neigs(j)) ~= c_id)
					% Puntos inter cluster
					printf("Trying %d <- %d ",labels(eps_neigs(j)),c_id)
					labels(eps_neigs(j)) = 99;
					%j = 1;
				end
				j++;
			end
			i
%			eps_neigs'
%			visited'
%			labels'
			eps_neigs = [];
		end
	end
end

figure, hold on;

for i = 1:L
	if (labels(i)==0)
		plot(x(i),y(i),' rx', 'linewidth',3);
	elseif (labels(i)==1)
		plot(x(i),y(i),' bo', 'linewidth',3);
	elseif (labels(i)==2)
		plot(x(i),y(i),' ms', 'linewidth',3);
	elseif (labels(i)==3)
		plot(x(i),y(i),' cp', 'linewidth',3);
	elseif (labels(i)==99)
		plot(x(i),y(i),' k^', 'linewidth',3);
	else
		plot(x(i),y(i),' g+', 'linewidth',3);
	end
		text(x(i),y(i),{num2str(i), [' neighs: ' num2str(np(i))] });%'VerticalAlignment','bottom', 'HorizontalAlignment','right'))
end

hold off;