% accuracy.m
%
% computes the confusion matrix and average misclassification error (also called accuracy) 
% conf_matrix is a matrix with element conf_matrix(i,j) showing
% how many examples from class 'i' were predicted to be of class 'j'
% Note that it works on multiclass problems. 

function [acc, conf_matrix] = accuracy(pred_y,true_y)

u = unique(pred_y);
for i=1:length(u)
   for j=1:length(u)
      conf_matrix(i,j) = length(find(pred_y == u(j) & true_y == u(i)));
   end
end
acc=sum(diag(conf_matrix))/length(true_y);

return