For loop for different datasets and conditions for EEGLAB

I have to analyze some EEG data and I am trying to automatize the pre-processing procedure.

I have 40 participants. Every participants has 4 different files for 4 conditions.

So the files are saved as

1-1  
1-2  
1-3  
1-4  
2-1  
2-2  
2-3  
2-4  
...

up to 40-4

The files are from BioSemi (.bdf)

I have been able to automatize the pre-processing procedure, but every time I have to chose a different file, run the script, and save it.

I would like to run a for loop that does it all by itself (take 1-1, run the pre-processing, save, take 1-2...etc).

Following I am pasting what I've got so far.

I've been trying all day to write a for loop, but it is just not working.

I would really appreciate any help.

This is the current pre-processing script:

subject = '1-1.bdf'  

%Open EEGLAB and inizialize several EEGLAB variables (listed in the output
%function  
[ALLEEG EEG CURRENTSET ALLCOM] = eeglab;  

%Load a file  
%EEG=pop_loadset;  % pop up window to input arguments  

EEG = pop_biosig(subject)  %Reads in the dataset frin a BIOSEMI file  

% Stores the dataset into EEGLAB  
[ALLEEG EEG CURRENTSET ] = eeg_store(ALLEEG, EEG);  

%Change sampling rate to 512  
EEG = eeg_checkset( EEG );    
EEG = pop_resample( EEG, 512);    
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, CURRENTSET); %save it as a new dataset  

% Edit Channel Location  
EEG = eeg_checkset( EEG );  
EEG=pop_chanedit(EEG, 'lookup','D:\\Matlab\\eeglab_current\\eeglab13_5_4b\\plugins\\dipfit2.3\\standard_BESA\\standard-10-5-cap385.elp');  
% Store the dataset into EEGLAB  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');  

% Add some comments  
EEG.comments = pop_comments(EEG.comments,'','Sampling rate was changed to 512.',1);  
% You can see the comments stored with the dataset either by typing >> EEG.comments or selecting the menu option Edit->About this dataset.  

%Select Data. Remove EXG5:EXG8   
EEG = eeg_checkset( EEG );  
EEG = pop_select( EEG,'nochannel',{'EXG5' 'EXG6' 'EXG7' 'EXG8'});  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');  


%HighPassFilter 0.5  
EEG = eeg_checkset( EEG );  
EEG = pop_eegfilt( EEG, 0.5, 0, [], [0], 0, 0, 'fir1', 0);  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');  

%LowPassFilter 50  
EEG = eeg_checkset( EEG );  
EEG = pop_eegfilt( EEG, 0, 50, [], [0], 0, 0, 'fir1', 0);  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');  


%ReReference to 35 36 (EXG3. EXG4)  
EEG = eeg_checkset( EEG );  
EEG = pop_reref( EEG, [35 36] );  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');   

% Reject Continuous By Eye  
EEG = eeg_checkset( EEG );  
pop_eegplot( EEG, 1, 0, 1);  

eeglab redraw % Update the EEGLAB window to view changes  

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%Automatic Channel Rejection  
EEG = eeg_checkset( EEG );  
EEG = pop_rejchan(EEG, 'elec',[1:34]   ,'threshold',5,'norm','on','measure','prob');  
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'overwrite','on','gui','off');  

eeglab redraw % Update the EEGLAB window to view changes

Solution

Here's how you can access the filenames in a loop, so that you can run your MATLAB script. The simplest thing to do is put your .bdf files in a folder by themselves. Then write a function that wraps the functionality you want, like this:

function run_script_with_loop(pathname)

file_struct_list = dir([pathname filesep() '*.bdf']);  %% get list of .bdf files in the pathname specified

filename_list = {file_struct_list.name};  %% extract the filenames into a cellarray
for subject = filename_list  %% this iterates over the elements of the cell array, one-by-one, setting the `filename` variable like a loop variable
    [ALLEEG EEG CURRENTSET ALLCOM] = eeglab;  
    full_pathname = [pathname filesep() subject{1}];
    EEG = pop_biosig(full_pathname);  %% perform your processing
    ...
end

A few comments:

I'm trying to be platform agnostic with the use of filesep() so this should work on linux / mac/ windows. If you're running the code in the same directory as the data files, you can certainly simplify this
Make sure you use curly braces {} when dereferencing subject. If you use the standard matlab array reference with subject(1), then you will get a cell-array containing the filename string, instead of just the plain filename string
The dir() command in MATLAB works just like dir in windows, or ls in Linux, and you can use wildcards to get customized lists of files, like dir('1-*.bdf') to only get a list of subject 1's data files