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function model = oaasvm(data,options) % OAASVM Multi-class SVM using One-Agains-All decomposition. % % Synopsis: % model = oaasvm( data ) % model = oaasvm( data, options) % % Description: % model = oaasvm( data ) uses one-agains-all deconposition % to train the multi-class Support Vector Machines (SVM) % classifier. The classification into nclass classes % is decomposed to nclass binary problems. % % model = oaasvm( data, options) allows to specify the % binary SVM solver and its paramaters. % % Input: % data [struct] Training data: % .X [dim x num_data] Training vectors. % .y [1 x num_data] Labels of training data (1,2,...,nclass). % % options [struct] Control parameters: % .solver [string] Function which implements the binary SVM % solver; (default 'smo'). % .verb [1x1] If 1 then a progress info is displayed (default 0). % The other fileds of options specifies the options of the binary % solver (e.g., ker, arg, C). See help of the selected solver. % % Output: % model [struct] Multi-class SVM classifier: % .Alpha [nsv x nclass] Weights (Lagrangians). % .b [nclass x 1] Biases of discriminant functions. % .sv.X [dim x nsv] Support vectors. % .nsv [1x1] Number of support vectors. % .trnerr [1x1] Training error. % .kercnt [1x1] Number of kernel evaluations. % .options [struct[ Copy of input argument options. % % Example: % data = load('pentagon'); % options = struct('ker','rbf','arg',1,'C',10,'verb',1); % model = oaasvm(data,options); % figure; % ppatterns(data); ppatterns( model.sv.X, 'ok',13); % pboundary( model ); % % See also % SVMCLASS, OAOSVM. % % 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: % 27-may-2004, VF, completely re-programed % 18-sep-2001, V. Franc, created % Process inputs %----------------------------- if nargin < 2, options = []; else options=c2s(options); end if ~isfield(options,'verb'), options.verb = 0; end if ~isfield(options,'solver'), options.solver = 'smo'; end if ~isfield(options,'ker'), options.ker = 'linear'; end if ~isfield(options,'arg'), options.arg = 1; end if ~isfield(options,'C'), options.C = inf; end [dim,num_data] = size(data.X); nclass = max(data.y); % display info %--------------------- if options.verb == 1, fprintf('Binary rules: %d\n', nclass); fprintf('Training data: %d\n', num_data); fprintf('Dimension: %d\n', dim); if isfield( options, 'ker'), fprintf('Kernel: %s\n', options.ker); end if isfield( options, 'arg'), fprintf('arg: %f\n', options.arg(1)); end if isfield( options, 'C'), fprintf('C: %f\n', options.C); end end %---------------------------------------- Alpha = zeros(num_data,nclass); b = zeros(nclass,1); orig_labels = data.y; kercnt = 0; % One-Against-All decomposition %---------------------------------------- for i=1:nclass, if options.verb==1, fprintf('Training rule %d', i); end % set binary subtask %--------------------------------------------- bin_labels = zeros(1,num_data); bin_labels(find( orig_labels==i)) = 1; bin_labels(find( orig_labels~=i)) = 2; data.y = bin_labels; % solve binary subtask %------------------------------------- bin_model = feval( options.solver, data, options ); Alpha(bin_model.sv.inx,i) = bin_model.Alpha(:); b(i) = bin_model.b; kercnt = kercnt + bin_model.kercnt; % progress info %---------------------------- if options.verb ==1, if isfield(bin_model, 'trnerr'), fprintf(': trnerr = %.4f', bin_model.trnerr); end if isfield(bin_model, 'margin'), fprintf(', margin = %f', bin_model.margin ); end fprintf('\n'); end end % set output model %--------------------------------- % indices of all support vectors inx = find(sum(abs(Alpha),2)~= 0); model.Alpha = Alpha(inx,:); model.b = b; model.sv.X = data.X(:,inx); model.sv.y = orig_labels(inx); model.sv.inx = inx; model.nsv = length(inx); model.kercnt = kercnt; model.options = options; model.fun = 'svmclass'; model.trnerr = cerror( svmclass(data.X, model), orig_labels ); if strcmp(options.ker,'linear') == 1, model.W = model.sv.X*model.Alpha; end % display info %-------------------- if options.verb == 1, fprintf('Total training error = %.4f\n', model.trnerr); end return; % EOF