Subtraction script while ignoring timestamps in subject names

1

Hi, I would like to produce a script with a subtraction of ERPs subject by subject, across different conditions, e.g.: condition1 subject1 - condition2 subject1, condition1 subject2 - condition2 subject2 etc. (and in some cases I need to subtract the ERPs with an opposite sign, which contain a word "| opposite" after the timestamp which I need to keep not to confuse with the original ERPs since both are in the same directory).

When I try to adapt the script produced by brainstorm, subject names contain timestamps which are unpredictable. Using * instead of the last part of timestamps does not get recognized by brainstorm. How can I proceed to ignore these timestamps?

Here is an example of my script:

% Script generated by Brainstorm (24-Apr-2020)

% Input files
sFiles = {...
'erps_s0001/xxx/data_210316_2118.mat'};
sFiles2 = {...
'erps_s0001/xxx/data_210316_2118_opposite.mat'};

% Start a new report
bst_report('Start', sFiles);

% Process: Difference: A-B
sFiles = bst_process('CallProcess', 'process_diff_ab', sFiles, sFiles2);

% Save and display report
ReportFile = bst_report('Save', sFiles);
bst_report('Open', ReportFile);
% bst_report('Export', ReportFile, ExportDir);

I am trying to change it into:

% Input files
sFiles = {...
'erps_s0001/xxx/data*.mat'};
sFiles2 = {...
'erps_s0001/xxx/data*opposite.mat'};

  • but it doesn't work.

Eventually I would like to enter all subjects in the loop (but so that the subtraction occurs subject by subject).

Thanks a lot for your help!!

2

You need to select the files with one of the file selection processes before, in order to get the sFiles structures for all you files:

3

Thanks a lot Francois!
What I don't quite understand - how to script subtractions on the individual subject-by-subject level if subjects' filenames are all collected within sFiles? I need to be sure that condition1 subject1 gets subtracted from condition2 subject1, and not from subject2 or the total subtraction of the average.

Thank you so much for your help!!

4

From the Process2 tab, the Subtraction process process the files by pairs in the order the files where given in input.

Alternatively, write a script with a loop over the subjects, as illustrated on the Scripting or Group analysis advanced tutorials.