function [nsignals, codebook, oldcodebook, scheme] = code(signals,codetype,codetype_args,oldcodebook,fctdist,fctdist_args)% Encode and decode a multi-class classification task into multiple binary classifiers%% >> Yc = code(Y, codebook)%% The coding is defined by the codebook. The codebook is% represented by a matrix where the columns represent all different% classes and the rows indicate the result of the binary% classifiers. An example is given: the 3 classes with original% labels [1 2 3] can be encoded in the following codebook (using Minimal Output Encoding):%% >> codebook%     = [-1  -1  1;%         1  -1  1]% % For this codebook, a member of the first class is found if the% first binary classifier is negative and the second classifier is% positive. A don't care is represented by eps. By default it is% assumed that the original classes are represented as different% numerical labels. One can overrule this by passing the% old_codebook which contains information about the old representation.% % Different encoding schemes are available:% %     1. Minimum Output Coding (code_MOC) %     2. Error Correcting Output Code (code_ECOC)%       This coding scheme uses redundant bits. %     3. One versus All Coding (code_OneVsAll)%     4. One Versus One Coding (code_OneVsOns)% % Different decoding schemes are implemented:% %     1. Hamming Distance (codedist_hamming) %     2. Bayesian Distance Measure (codedist_bay)% %% Full syntax%%     1. For encoding:% % >> [Yc, codebook, old_codebook] = code(Y, codefct)% >> [Yc, codebook, old_codebook] = code(Y, codefct, codefct_args)% >> Yc = code(Y, given_codebook)% %       Outputs    %         Yc               : N x nbits encoded output classifier%         codebook(*)      : nbits*nc matrix representing the used encoding%         old_codebook(*)  : d*nc matrix representing the original encoding%       Inputs    %         Y                : N x d matrix representing the original classifier%         codefct(*)       : Function to generate a new codebook (e.g. code_MOC)%         codefct_args(*)  : Extra arguments for codefct%         given_codebook(*): nbits*nc matrix representing the encoding to use% %     2. For decoding:% % >> Yd = code(Yc, old_codebook,[], codebook)% >> Yd = code(Yc, old_codebook,[], codebook, codedist_fct)% >> Yd = code(Yc, old_codebook,[], codebook, codedist_fct, codedist_args)% %       Outputs    %         Yd               : N x nc decoded output classifier%       Inputs    %         Y                : N x d matrix representing the original classifier%         codebook         : d*nc matrix representing the original encoding%         old_codebook     : bits*nc matrix representing the encoding of the given classifier%         codedist_fct     : Function to calculate the distance between to encoded classifiers (e.g. codedist_hamming)%         codedist_args(*) : Extra arguments of codedist_fct% % % see also%    code_ECOC, code_MOC, code_OneVsAll, code_OneVsOne, codedist_hamming		    % Copyright (c) 2002,  KULeuven-ESAT-SCD, License & help @ http://www.esat.kuleuven.ac.be/sista/lssvmlab%% default handling;%eval('fctdist(1,1);','fctdist = ''codedist_hamming'';');eval('if isempty(oldcodebook),ss = sort(signals(:,1));  oldcodebook = ss([1;find(ss(2:end)~=ss(1:end-1))+1])'';end ',...     'ss = sort(signals(:,1));  oldcodebook = ss([1;find(ss(2:end)~=ss(1:end-1))+1])'';');n = size(signals,1);mc = size(oldcodebook,2);% codebook or codetype% initialise the new scheme used for preprocessing% Binary,Ctu,cAtegorical,Originalif isstr(codetype),  eval('[codebook,scheme] = feval(codetype, mc, codetype_args{:});',...       '[codebook,scheme] = feval(codetype, mc);');else  codebook = codetype;  scheme=[]; for t=1:size(codebook,2),scheme=[scheme 'b']; endend%% convert from old coding towards new coding%if nargin==6,  dist = feval(fctdist, signals, oldcodebook,fctdist_args{:});else  dist = feval(fctdist, signals, oldcodebook);endfor t = 1:n,  [m,mi] = min(dist(t,:));  m2 = min(dist(t,[1:(mi-1) (mi+1):end]));  if m==m2,     nsignals(t,:) = -inf+codebook(:,mi)';  else     nsignals(t,:) = codebook(:,mi)';  endend