[FieldTrip] Error using ft_read_header

Tue Jun 23 15:18:28 CEST 2020

Dear Stephen,

Thanks for the quick response!

I have been initially using another function, ft_read_data (which calls on ft_read_header) as part of some code to load and convert .mat files to .csv files - and it was in this code that the bug/error first showed up.

filename = 'my_data.mat';

dat = ft_read_data(filename);

writematrix(dat, 'my_data.csv')

Error using feval

Attempt to execute SCRIPT matlab as a function:
/Applications/MATLAB_R2019b.app/toolbox/matlab/general/matlab.m

Error in ft_read_header (line 2594)
      hdr = feval(headerformat, filename);

Error in ft_read_data (line 214)
  hdr = ft_read_header(filename, 'headerformat', headerformat, 'chanindx',
  chanindx, 'checkmaxfilter', checkmaxfilter);

There are other ways of converting .mat to .csv files, so that's not a huge problem, however, it seems that whenever I use any function that requires/calls on  ft_read_header the same error comes up.  So, I haven't been able to use quite a few Field Trip functions as a result.

I am working with data that has been preprocessed by another lab, so unfortunately I don't have more code than this to show you. However, I get the same error with a different dataset, which I was also previously able to run through these functions without a problem.

Thank you in advance for your time!

Best,
Alina.
________________________________
From: fieldtrip <fieldtrip-bounces at science.ru.nl> on behalf of Stephen Whitmarsh <stephen.whitmarsh at gmail.com>
Sent: 23 June 2020 13:04
To: FieldTrip discussion list <fieldtrip at science.ru.nl>
Subject: Re: [FieldTrip] Error using ft_read_header

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Dear Alina,

Not sure there is not something more sinister at play in the code somewhere (I mean a bug or installation error), but I would start by asking why you are using  ft_read_header to load a .mat file?

Are you sure you don't just want to load the matfile with MATLAB's load functions? I.e. header = load('myfilename.mat')? Or, otherwise, read the header of an original EEG/MEG datafile (some EEG/MEG dataformat)?

If not, and for a more informed response, please specify a bit more of the code you use to process/write and then (try to) load the header.

Cheers,
Stephen

Op di 23 jun. 2020 om 13:30 schreef Bondarenko, Alina I <alina.bondarenko19 at imperial.ac.uk<mailto:alina.bondarenko19 at imperial.ac.uk>>:
Hello all,

I'll try to describe the problem I've been having as clearly as I can here:

  *   I'm trying to use a Field Trip function ft_read_header to load some .mat files.

  *   When I try to load up a file using ft_read_header, I get an error message saying that within the ft_read_header script, the function feval is being used incorrectly. Namely, that feval is trying to execute a script called matlab as if it were a function.

Error using feval
Attempt to execute SCRIPT matlab as a function:
/Applications/MATLAB_R2019b.app/toolbox/matlab/general/matlab.m

  *   When I look inside the ft_read_header script, the line (2594) that gives the error looks like this:

feval(headerformat, filename)

Where headerformat is assigned a string 'matlab', which is supposed to represent the file type of the file I'm trying to load. Filename is a string variable I assign, e.g. filename = 'session1.mat'.

Headerformat is assigned the string 'matlab' in line 203 of ft_read_header (found in debugging mode):

headerformat = ft_filetype(filename);

  *   Feval is supposed to "evaluate a function" (I'm not quite sure exactly what this means based on the documentation), but it's first argument is supposed to be a function name, so I guess that a string saying 'matlab' should have always thrown an error, but the thing is that this function used to work just fine for me before. I also haven't edited any of the built in Field Trip scripts, so I'm not sure why this has stopped working.

Here are some things I've tried to fix the problem:

  *
I looked up the 'executing script as function error' and thought that since Matlab would like to execute a function, but is instead executing a script of the same name, then changing the name of the script could stop the problem.

However, when I change the name of the matlab.m script (e.g. to matlab_change.m) I get this error message instead:

Error using feval
Previously accessible file
"/Applications/MATLAB_R2019b.app/toolbox/matlab/general/matlab.m" is now inaccessible.

The only file called matlab.m is a short text file containing some info about what Matlab is and what it can be used for (I used "which matlab -all" to check this). There are no functions called matlab.

  *   In between the time when this function was working fine for me, and when it started showing me this error, I installed several versions of OSL and SPM on my computer. So, I uninstalled all these things.
  *   Uninstalled and reinstalled Field Trip
  *   Uninstalled and reinstalled Matlab
  *   Copy pasted all the functions involved and saved these under different names in different folders. Tried running them - got the same error.

I would greatly appreciate anyone's help on this! This error has been driving me crazy.

All the best,
Alina.

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