交叉驗證代碼(matlab code of cross validation)

%說明：下面是我自己寫的matlab代碼，其實matlab有內建的交叉驗證代碼crossvalind，見Chunhou Zheng師兄的Metasample Based Sparse Representation for Tumor提供的代碼
%說明：Main_gene10FOLD_1.m有，用法非常簡單，和自己編寫的實現的是同樣的功能

% 10-fold cross validation
%This code is written by Gui Jie in the afternoon 2009/06/08.
%If you have find some bugs in the codes, feel free to contract me
% Reference:
%1. Algorithm 2 of "Shuiwang Ji and Jieping Ye. Generalized Linear Discriminant Analysis: A
%  Unified Framework and Efficient Model Selection. IEEE Transactions on Neural Networks.
%  Vol. 19, No. 10, pp. 1768-1782, 2008."
%2.Foot note 4 of "F.Wang,et al.,marginFace:A novel face recognition method by average neighborhood 
%  margin maximization,Pattern Recognition (2009)"
v=10;% If v=4,it means 4-fold cross validation.
step=floor(size(fea_train,1)/v);
for j =1:v
    if j~= v
        startpoint=(j-1)*step+1;
        endpoint=(j)*step;
    else
        startpoint=(j-1)*step+1;
        endpoint=size(fea_train,1);
    end
    cv_p=startpoint:endpoint; %%%% test set position
   
    %%%%%%%%%%%%%% test set
     Test_data=fea_train(cv_p,:);
     Test_lab=gnd_train(cv_p,:);  %%%%label
    %%%%%%%%%%%%%% training data
     Train_data=fea_train;
     Train_data(cv_p,:)='';      
     Train_lab=gnd_train;
     Train_lab(cv_p,:)='';
end