www.pudn.com > voicebox2.zip > KMEANS.M

function [x,esq,j] = kmeans(d,k,x0) 
%KMEANS Vector quantisation using K-means algorithm [X,ESQ,J]=(D,K,X0) 
%Inputs: 
% D contains data vectors (one per row) 
% K is number of centres required 
% X0 are the initial centres (optional) 
% 
%Outputs: 
% X is output row vectors (K rows) 
% ESQ is mean square error 
% J indicates which centre each data vector belongs to 
 
%  Based on a routine by Chuck Anderson, anderson@cs.colostate.edu, 1996 
 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Mon Jul 27 15:48:23 1998 
% 
%   VOICEBOX home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   This program is free software; you can redistribute it and/or modify 
%   it under the terms of the GNU General Public License as published by 
%   the Free Software Foundation; either version 2 of the License, or 
%   (at your option) any later version. 
% 
%   This program is distributed in the hope that it will be useful, 
%   but WITHOUT ANY WARRANTY; without even the implied warranty of 
%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
%   GNU General Public License for more details. 
% 
%   You can obtain a copy of the GNU General Public License from 
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to 
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
[n,p] = size(d); 
if nargin<3 
   x = d(ceil(rand(1,k)*n),:); 
else 
   x=x0; 
end 
y = x+1; 
 
while any(x(:) ~= y(:)) 
   z = disteusq(d,x,'x'); 
   [m,j] = min(z,[],2); 
   y = x; 
   for i=1:k 
      s = j==i; 
      if any(s) 
         x(i,:) = mean(d(s,:),1); 
      else 
         q=find(m~=0); 
         if isempty(q) break; end 
         r=q(ceil(rand*length(q))); 
         x(i,:) = d(r,:); 
         m(r)=0; 
         y=x+1; 
      end 
   end 
end 
esq=mean(m,1);