function xy2svmlight(data,file_name)% XY2SVMLIGHT Converts data set to SVM^{light} format.%% Synopsis:%  xy2svmlight(data,file_name).%% Description:%  This function saves training data to text file required%  by the SVM^{light} software. %% Input:%  data.X [dim x num_data] training data stored as column vectors.%  data.y [1 x num_data] labels of traning data; possible values %   are 1 (first class) and 2 (second class).%% Output:%  Text file 'file_name' in SVM^{Light} format.%% See also SVMLIGHT.%% About: Statistical Pattern Recognition Toolbox% (C) 1999-2003, Written by Vojtech Franc and Vaclav Hlavac% <a href="http://www.cvut.cz">Czech Technical University Prague</a>% <a href="http://www.feld.cvut.cz">Faculty of Electrical Engineering</a>% <a href="http://cmp.felk.cvut.cz">Center for Machine Perception</a>% Modifications:% 14-Jan-2003, VF% 30-apr-2001, V. Franc, createdfid = fopen( file_name, 'w+');dim=size(data.X,1);num_data=size(data.X,2);txt = zeros(1,2*dim);inx1 = 1:2:2*dim;txt(inx1) = 1:dim;inx2 = 2:2:2*dim;for i=1:num_data,  if data.y(i) == 1,     fprintf(fid,'+1 ');   elseif data.y(i) == 2,    fprintf(fid,'-1 ');   else    fprintf(fid,'0 ');   end          txt(inx2) = data.X(:,i);    fprintf( fid, '%d:%f ', txt );  fprintf(fid,'\n');endfclose(fid);return;