PSC

PSC.m

% Author:  Sharif Shahadat
% Email:   sshahada@uno.edu
% Website: http://sharifshahadat.com


% The following code is inspired by the following paper:
% S.C.M. Cohen ;  L.N. de Castro., "Data Clustering with Particle Swarms" 
% Evolutionary Computation, 2006. CEC 2006. IEEE Congress on, pp.1792-1798, 16-21 July 2006
% doi: 10.1109/CEC.2006.1688524
% URL: http://ieeexplore.ieee.org/document/1688524/

clc; clear; close;
%% Initialization
    data_set=[unifrnd(0, 1, [2, 100]), unifrnd(3, 4, [2, 100])]';
    max_it=150;
    vmax=0.01;
    n_particles=3;
    w=0.95;
    n_cluster_per_particle=3;
    global Y
    
    phi1=0; % 1.1; 
    phi2=0; % 0.8;
    phi3=0.005; % 0.3;
    phi4=0.06;
     
    Y = [data_set(:,1)/max(data_set(:,1)) data_set(:,2)/max(data_set(:,2))];
    N=max(size(data_set));
    x=rand(n_cluster_per_particle*n_particles,2); % usually every particle xi initialized at random
    c = reshape(x,1, []);
    
    v=vmax*(2*rand(n_particles*n_cluster_per_particle,2)-1); % at random, vi in [-vmax,vmax]
    distYX=linspace(1e99,1e99,n_part);
    pI=[0 0];
    pG=[0 0];
    win_counter=zeros(max(size(x)),1);
    t=1;
 %% Particle Swarm Clustering   
 while t < max_it
        win_counter=zeros(n_particles*n_cluster_per_particle,1);
        for i = 1 : N  %for each data
                for j=1:n_particles*n_cluster_per_particle
                        distYX(j) = dist(Y(i,:),x(j,:)');
                end
                distMatrix(:,i)=distYX;
                for k=1:n_cluster_per_particle
                particle=mat2cell(distMatrix,[3 3 3], N);
                end
            I = find(distYX==min(distYX));
            f= @(x) sum(sum(bsxfun(@minus,Y,x).^2)); % distance function
            if f(x(I,:)) < f(pI)
                pI = x(I,:);
            end 
            if f(x(I,:)) < f(pG)
                pG = x(I,:);
            end
            
            v(I,:) = min(vmax,  max(-vmax, v(I,:) + phi1*(pI - x(I,:)) + phi2*(pG -  x(I,:)) + phi3*(Y(i,:) -  x(I,:))));
            x(I,:)=x(I,:)+w*v(I,:);
        end
        
        w = 0.95*w;
 
        % for plotting
        plot(Y(:,1),Y(:,2),'bo'),hold on;
        drawnow
        plot(x(:,1),x(:,2),'k*'),hold off;
        pause(0.1);
        t = t + 1;
 end
disp(x)