function error=cerror(y1,y2,label)% CERROR Computes classification error.%% Synopsis:%  error = cerror(y1,y2)%  error = cerror(y1,y2,label) %% Description:%  error = cerror(y1,y2) returns classification error, i.e.,%      error=  1/length(y1) sum_i L( y1(i), y2(i))%%    where L(a,b)=0 if a==b and L(a,b)=1 if a ~= b.%%  error = cerror(y1,y2,label) considers only labels%    find(y2==label), i.e., if y1,y2 from {-1,1} then%%   false_positives_rate = cerror(y1,y2,-1)%   false_negatives_rate = cerror(y1,y2,+1)%% Input:%  y1 [1 x n] Vector of integers (response of classifier).%  y2 [1 x n] Vector of integers (ground truth).%  label [int] Selected label.%% Output:%  error [real] Error. %% Example:%  classifier  = [1,1,1,2]%  groundtruth = [2,1,2,1]%  error = cerror(classifier,groundtruth)%  false_pos = cerror(classifier,groundtruth,2)%  false_neg = cerror(classifier,groundtruth,1)%% See also %  ROC%% About: Statistical Pattern Recognition Toolbox% (C) 1999-2003, Written by Vojtech Franc and Vaclav Hlavac% <a href="http://www.cvut.cz">Czech Technical University Prague</a>% <a href="http://www.feld.cvut.cz">Faculty of Electrical Engineering</a>% <a href="http://cmp.felk.cvut.cz">Center for Machine Perception</a>% Modifications:% 09-jun-2004, VF% 14-Jan-2003, VFy1=y1(:);y2=y2(:);if nargin < 3,  error=length(find((y1-y2)~=0))/length(y1);else  inx = find(y2==label);  error = length( find(y1(inx)~=label) )/length(inx);endreturn;