Home > biosig > t400 > findclassifier.m

findclassifier

PURPOSE ^

FINDCLASSIFIER

SYNOPSIS ^

function [CC,KAPPA,tsd]=findclassifier(D,TRIG,cl,MODE1,t0,MODE)

DESCRIPTION ^

 FINDCLASSIFIER
   identifies and validates a classifier of a BCI systems [1-3]. 
   Several evaluation criteria are obtained [4]. Several Cross-validation 
   procedures are supported. 

 By default, a Trial-based Leave-One-Out-Method is used for Crossvalidation    
    MODE.Segments = class_times; 
    MODE.WIN   = t_ref; 
       [CC,Q,TSD] = findclassifier(D,TRIG,Class,MODE,t_ref,TYPE);
 Also this will work but its use is discouraged (it might become obsolete). 
       [CC,Q,TSD] = findclassifier(D,TRIG,Class,class_times,t_ref,TYPE);
 An K-fold cross-validation can be applied in this way: 
       ng = floor([0:length(Class)-1]'/length(Class)*K);
       [CC,Q,TSD] = findclassifier(D,TRIG,[Class,ng],...);

 D     data, each row is one time point
 TRIG    trigger time points
 Class class information
 class_times    classification times, combinations of times must be in one row 
 t_ref    reference time for Class 0 (optional)
 TYPE  determines the type of classifier (see HELP TEST_SC for complete list)
       bthe default method is 'LD3'

 CC     contains the classifier and the validation results
 Q      is a list of classification quality for each time segment (as defined by 'class_times')
 TSD     returns the discrimination 

 Example: 
  [CC,Q,TSD]=findclassifier(d,find(trig>0.5)-257,~mod(1:80,2),reshape(1:14*128,16,14*8)');

 see also: TRAIN_SC, TEST_SC, BCI4EVAL

 Reference(s):
 [1] Schl�l A, Neuper C, Pfurtscheller G
     Estimating the mutual information of an EEG-based Brain-Computer-Interface
      Biomedizinische Technik 47(1-2): 3-8, 2002.
 [2] Schl�l A, Keinrath C, Scherer R, Pfurtscheller G,
    Information transfer of an EEG-based Bran-computer interface.
    Proceedings of the 1st International IEEE EMBS Conference on Neural Engineering, Capri, Italy, Mar 20-22, 2003
 [3] Schl�l A, Lee FY, Bischof H, Pfurtscheller G
    Characterization of Four-Class Motor Imagery EEG Data for the BCI-Competition 2005.
    Journal of neural engineering 2 (2005) 4, S. L14-L22
 [4] Schl�l A, Kronegg J, Huggins JE, Mason SG;
    Evaluation criteria in BCI research.
    (Eds.) G. Dornhege, J.R. Millan, T. Hinterberger, D.J. McFarland, K.-R.M�ler;
    Towards Brain-Computer Interfacing, MIT Press, p327-342, 2007

CROSS-REFERENCE INFORMATION ^

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