eegh & the command history

What does this show?

After you click Ok in this window, type eegh in the command window. The matching line is:

EEG = pop_eegfiltnew(EEG, 'locutoff',0.1,'plotfreqz',1);

Each field you filled in the window is in the line: 'locutoff',0.1 is the lower edge, and 'plotfreqz',1 is the ticked Plot frequency response box.

Why do I need this step?

This history is your first script, and you did not type a single character of it. Save it to a file, and you can repeat the same analysis in one click, or apply it to another participant.

The history is also an exact record of what you did. A month from now you will not remember which filter edge you chose. The history will.

How do I do it in EEGLAB?

Start a fresh session as in “Starting point”: clear, then eeglab. Running eeglab starts a new, empty history, so it does not mix with commands from an earlier session.

First: run a few steps from the GUI

1. Open File › then Load existing dataset and choose eeglab_data.set from the sample_data folder inside the EEGLAB folder.
2. Open Tools › then Filter the data › then Basic FIR filter (new, default). Type 0.1 in Lower edge of the frequency pass band (Hz) and press Ok. Close the filter response window and name the dataset D1 hp0.1.
3. Open the same menu again to remove 60 Hz line noise. Type 58 in Lower edge of the frequency pass band (Hz) and 62 in Higher edge of the frequency pass band (Hz), and check Notch filter the data instead of pass band. Press Ok and name the dataset D1 hp0.1 notch60.
4. Open Plot › then Channel data (scroll), then close the window.

Second: show the history

5. In the MATLAB command window, type eegh and press Enter. EEGLAB prints every command of the session, oldest first. It will look like this (your path will differ):

[ALLEEG EEG CURRENTSET ALLCOM] = eeglab;
EEG = pop_loadset('filename','eeglab_data.set','filepath','C:\eeglab2026.1\sample_data\');
[ALLEEG, EEG, CURRENTSET] = eeg_store( ALLEEG, EEG, 0 );
EEG = pop_eegfiltnew(EEG, 'locutoff',0.1,'plotfreqz',1);
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 1,'setname','D1 hp0.1','gui','off');
EEG = pop_eegfiltnew(EEG, 'locutoff',58,'hicutoff',62,'revfilt',1,'plotfreqz',1);
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 2,'setname','D1 hp0.1 notch60','gui','off');
pop_eegplot( EEG, 1, 1, 1);

6. Match each line to its step. Notice that the Notch filter the data instead of pass band checkbox became 'revfilt',1, and Plot frequency response became 'plotfreqz',1. This is how you learn the script name of each option from the GUI itself.

Third: save the history to a file

7. Open File › then History scripts › then Save session history script. The suggested name is eeglabhist.m. Change it to my_first_history.m and save it in your working folder.
8. Type EEG.history in the command window. This is the dataset history: the commands for the current dataset only, without the dataset management commands. It starts with lines you did not write, with paths like /Users/arno/...: this is the file’s history on the computers of the people who made it, because the history is saved inside the .set file and travels with it. Then comes a line that records the EEGLAB version, then the two filter lines, and at the end a pop_eegplot line, because you opened the scroll window from the menu.
9. To save it to a file, open File › then History scripts › then Save dataset history script.

Fourth: run the history

10. Close EEGLAB, then type clear and close all.
11. Open my_first_history.m in the MATLAB editor and press Run. All the steps repeat on their own, and the scroll window opens at the end. You can also run it from File › then History scripts › then Run script.

How do I write it as code?

The history script works as is, but it is written for the machine, not for you. Clean it before you rely on it. Here is the same history after cleaning:

% Rebuilt from the EEGLAB session history (eegh)
eeglab nogui
eeglabRoot = fileparts(which('eeglab'));

% Load the sample dataset (portable path, works on any computer)
EEG = pop_loadset('filename', 'eeglab_data.set', 'filepath', fullfile(eeglabRoot, 'sample_data'));

% High-pass: passband edge at 0.1 Hz
[EEG, com] = pop_eegfiltnew(EEG, 'locutoff', 0.1);
EEG = eeg_hist(EEG, com);

% Line noise: notch between 58 and 62 Hz
[EEG, com] = pop_eegfiltnew(EEG, 'locutoff', 58, 'hicutoff', 62, 'revfilt', 1);
EEG = eeg_hist(EEG, com);
EEG.setname = 'D1 hp0.1 notch60';
EEG = eeg_checkset(EEG);

% Save the dataset history to a file, for your records
pop_saveh(EEG.history, 'D1_hp0.1_notch60_history.m', pwd);

What changed from the raw history:

• The fixed path became fullfile(eeglabRoot, 'sample_data'), so the script works on any computer.
• 'plotfreqz',1 was removed, so no step stops at a plot window.
• The eeg_store and pop_newset lines were removed, because they manage datasets in the GUI. The script works on a single EEG variable, and the name goes in EEG.setname.
• eeglab nogui replaces eeglab, so EEGLAB loads its functions without opening the main window.
• Comments were added, because a line of code says what it does, and a comment says why.
• [EEG, com] and eeg_hist were added. pop_ functions return their command line as the second output com, and eeg_hist adds it to EEG.history. Without them the dataset history stays empty of the script’s steps, because EEGLAB writes the history automatically only for commands run from the menus.

Which value should I choose?

How do I check it worked?

1. The script runs on its own. Run the clean script in a fresh session. It should finish without any error and without asking you to click anything.
2. Same processing. After it runs, type EEG.history. You should see the two filter lines with the same numbers you chose in the GUI: 0.1, then 58 and 62 with 'revfilt',1.
3. The history file exists. In your working folder you should find D1_hp0.1_notch60_history.m. Open it, and you will find the same two filter lines.

What mistakes do people make?

• Running eeglab again before saving the session history. eeglab starts an empty history. Save the history first, or rely on the EEG.history saved with the dataset.
• Sharing a script with a fixed path. A line like 'filepath','C:\Users\...' will not work on your colleague’s computer. Replace it with fullfile as in the script above.
• Expecting steps run outside the menus to be recorded. EEGLAB writes the history for commands run from the menus only. What you type yourself in the command window does not appear in eegh, and running pop_eegfiltnew from a script does not change EEG.history. If you want the saved file to carry its history, add EEG = eeg_hist(EEG, com); after each step, as in the script above.
• Running the dataset history as is. It starts with old lines from the file’s creator, with paths from their computer, so it stops at the first line. Copy only the processing lines from it, and start your script with a load command that uses a path from your own computer.

Going further

• EEGLAB Tutorial: https://eeglab.org/tutorials/11_Scripting/Using_EEGLAB_history.html (11. Write scripts > a. Using EEGLAB history)
• EEGLAB Tutorial: https://eeglab.org/tutorials/ConceptsGuide/EEGLAB_functions.html (EEGLAB functions)