osusvmclass.m

支持向量机实现程序

function  [Labels, scores]= osuSVMClass(Samples, Ns, AlphaY, SVs, Bias, Parameters)
% USAGE:
% [Labels, scores]= osuSVMClass(Samples, Ns, AlphaY, SVs, Bias, Parameters)
%
% DESCRIPTION:
% Classify a group of input patterns given a trained svm classifier.
%
% INPUTS:
% Samples: all the input patterns. (a row of column vectors)
% Ns: number of SVs for each class (a row vector). This parameter is valid only
%     for the multi-class case, and is 0 for the 1-svm and 2-class case.(a row vector or a scalar)
% AlphaY: Alpha * Y, where Alpha is the non-zero Lagrange Coefficients
%                    Y is the corresponding {1 -1} labels. 
%     in multi-class case:
%        [AlphaY_Class1, AlphaY_Class2, ..., AlphaY_ClassM]
%        +----Ns(1)----+----Ns(2)-----+----+---Ns(M)------+
% SVs : support vectors. That is, the patterns corresponding the non-zero
%       Alphas.
%     in multi-class case:
%        [SVs_Class1, SVs_Class2, ..., SVs_ClassM]
%        +--Ns(1)---+---Ns(2)---+----+---Ns(M)---+
% Bias : the bias in the decision function, which is AlphaY*Kernel(SVs',x)-Bias.
%     in multi-class case:
%        [Bias_Class1, Bias_Class2, ..., Bias_ClassM]
% Parameters: the paramters required by the training algorithm. 
%             (a 10-element row vector)
%            +-----------------------------------------------------------------
%            |Kernel Type| Degree | Gamma | Coefficient | C |Cache size|epsilon| 
%            +-----------------------------------------------------------------
%				 -------------------------------------------+
%            | SVM Type |	nu (nu-svm) | loss tolerance |				
%				 -------------------------------------------+
%            where Kernel Type:
%                   0 --- Linear
%                   1 --- Polynomial: (Gamma*<X(:,i),X(:,j)>+Coefficient)^Degree
%                   2 --- RBF: (exp(-Gamma*|X(:,i)-X(:,j)|^2))
%                   3 --- Sigmoid: tanh(Gamma*<X(:,i),X(:,j)>+Coefficient)
%                  Gamma: If the input value is zero, Gamma will be set defautly as
%                         1/(max_pattern_dimension) in the function. If the input
%                         value is non-zero, Gamma will remain unchanged in the 
%                         function.
%                  C: Cost of the constrain violation (for C-SVC & C-SVR)
%                  Cache Size: as the buffer to hold the <X(:,i),X(:,j)> (in MB)
%                  epsilon: tolerance of termination criterion
%                  SVM Type: 
%                   0 --- c-SVM classifier
%                   1 --- nu-SVM classifier
%                   2 --- 1-SVM 
%                   3 --- c-SVM regressioner
%                  nu: the nu used in nu-SVM classifer (for 1-SVM and nu-SVM)
%						 loss tolerance: the epsilon in epsilon-insensitive loss function	
%
% OUTPUTS
% Lables: the corresponding estimated class labels for the input patterns in Samples.
%        In multi-class case, it's a row vector, and the labels are {1, 2, 3, ..., M }
%        In 2-class case, it's a 
% scores: In the multi-class case, the decision function output for each class. 
%         (a M row matrix, each row is the decision function for a class)
%         In 2-class case, the decision funciton output of this 2-class problem
%
if (nargin ~= 6)
   disp(' Incorrect number of input variables.\n');
   help osuSVMClass;
else
   [svDim n]=size(SVs);
   [sampleDim n]=size(Samples);
   if sampleDim ~=svDim
      [Samples]=DimFit(Samples,svDim);
   end
   if Ns == 0 % the 1-svm or 2-class case (including c-svm and u-svm)
      [Labels, scores]= SVMClass(Samples, AlphaY, SVs, Bias, Parameters);
      if (Parameters(8) == 0) | (Parameters(8) == 1)
         Labels = (-1*Labels)/2+1.5;  % change the labels from {1 -1} format to {1 2} format
      end
   else % the multi-class case
      M=length(Ns);
      pos=1;
      for i=1:M
         [ClassRate, curDecisionValue]= SVMClass(Samples, AlphaY(pos:pos+Ns(i)-1), SVs(:,pos:pos+Ns(i)-1), Bias(i), Parameters);
         if i == 1      
            scores = curDecisionValue;
         else
            scores = [scores; curDecisionValue];
         end
         pos = pos + Ns(i);
      end
      [v Labels] = max(scores,[],1);
   end
end