% This program reads in ascii data files (ERP data: electrodes in columns, samples in rows),
% It finds peak value for each electrode within a given time interval
% and spits out this peak value as well as the latency of the peak for each
% electrode
% Heleen Slagter (slagter@wisc.edu), September 2005

clear all;

%% ***** EDIT THIS PART BETWEEN *** ONLY ******
% User-specific input
nsamples = 750;
nelectrodes = 129;
%specify interval to search for peak value (rowA to rowB)
RowA = 2;
RowB = 4;
sample_rate = 2; %sample rate in ms ; corresponding to 500Hz sr

%specifiy file names here
cond = {...
      'samplefile.1LX0',...
   };

%% ********************************   


ncond=length(cond);

% start loop in which each value is divided by 100
for condition = 1:ncond;
      
      % Open data file
      filename = sprintf('%s.txt', cond{condition});
      dat = fopen(filename);
      data = fscanf(dat, '%g %g', [nelectrodes nsamples]);
      data = data';
      fclose(dat);
      
      x = zeros(RowB-RowA,1);
      peak_values = zeros(1,nelectrodes); 
      latency_peak_sample = zeros(1,nelectrodes);       
      latency_peak_ms = zeros(1,nelectrodes);             
      for j = 1:nelectrodes;       %for each column (electrode) separately
          k = 1;
          for i = RowA:RowB;       %find peak value within specified interval
              x(k) = data(i,j);
              k=k+1;
          end;
          peak_values(j)=max(x);
          latency_peak_sample(j)=(RowA+(find(x==peak_values(1,j))))-1;
          latency_peak_ms(j)=latency_peak_sample(j)*sample_rate;
      end;
      
     output = zeros(3,nelectrodes); 
     output(1,:)=peak_values(1,:);
     output(2,:)=latency_peak_sample(1,:);
     output(3,:)=latency_peak_ms(1,:);
      % Save in output file (asci tab delimited)
      newfilename = sprintf('%s_%d-%d.txt', cond{condition}, RowA, RowB);
      dlmwrite(newfilename,output,'\t');
      
      
   
end;	% end condition loop