demo_crossval.m

load('fisheriris');

% meas: 150X4
% species: 150X1

CVO = cvpartition(species,'k',10);

% K-fold cross validation partition
%             N: 150
%   NumTestSets: 10
%     TrainSize: 135  135  135  135  135  135  135  135  135  135
%      TestSize: 15  15  15  15  15  15  15  15  15  15

err = zeros(CVO.NumTestSets, 1);

for i = 1:CVO.NumTestSets
  trIdx = CVO.training(i); % logical
  teIdx = CVO.test(i);

  ytest = classify(meas(teIdx,:), meas(trIdx,:), species(trIdx,:));
  err(i) = sum(~strcmp(ytest,species(teIdx)));
end

cvErr = sum(err)/sum(CVO.TestSize);