For loop to work on files in subfolders, while skipping the first file

I want todecode my data with tdt on MATLAB. I have a folder, this folder has 70 sub-folders. Each of the 70 sub-folders has four .mat files. I want to work on the 2nd three files while loading the first spm.mat file separately. How do I write a for loop that runs through these files so that after working on the loading the first file, I can work on each of the other 3 files sequentially then move to the next folder. These 3 files start with the letters voi (e g voi 1, voi 2). I used the folowing and got an error message: Dot indexing is not supported for variables of this type.

folders = dir('parent folder path'); % Captures all contents of parent folder
folders = folders([folders(:).isdir]==1); % Filter to just folders
folders = folders(3:end); % Remove unnecessary '.' and '..' directories
for i = 1:length(folders)
    path = [folders(i).folder,'\',folders(i).name]; % do work with path variable directing to each child folder.
    end
end

[Stephen23]

folders = folders(3:end); % Does NOT remove '.' and '..' directories

https://www.mathworks.com/matlabcentral/answers/1699230-folder-listing-with-dir-on-mac#answer_945260

https://www.mathworks.com/matlabcentral/answers/484430-using-struct-dir-selpath-what-do-and-mean-as-struct-name#answer_395754

https://www.mathworks.com/matlabcentral/answers/345841-unexplained-error-on-dir#answer_271627

https://www.mathworks.com/matlabcentral/answers/21150-function-call#comment_46042

https://www.mathworks.com/matlabcentral/answers/394807-create-text-file-containing-list-of-file-names#comment_556641

https://www.mathworks.com/matlabcentral/answers/288815-gui-for-loop-not-working-correctly#answer_224956

https://www.mathworks.com/matlabcentral/answers/40949-omitting-pointers-when-listing-folder-contents#answer_50568

https://www.mathworks.com/matlabcentral/answers/13978-list-of-files-sorting#answer_19278

As Walter Roberson wrote in that last link: "In short: if your code assumes that '.' and '..' are the first two entries in a directory, your code has a bug (even in MS Windows). If your code assumes that directory entries are returned in any sorted order, your code has a bug (in all OS.)"

[Monalisa Chikezie]

Thanks a lot for the response @Stephen23

Answer 1

[Image Analyst]

Here's one way:

topLevelFolder = pwd; % Wherever you want.
filePattern = fullfile(topLevelFolder, '**/*.*');
folders = dir(filePattern); % Captures all contents of parent folder and subfolders
% Filter to just folders
itsAFolder = [folders.isdir]
folders = folders(itsAFolder); 
% Get all folder names in a cell array.
folderNames = {folders.folder, folders.name}'
c = contains(folderNames, topLevelFolder)
folderNames = unique(folderNames(c))
% Loop over each folder and subfolder.
for k = 1:length(folderNames)
    thisFolder = folderNames{k};
    fprintf('Processing folder : "%s".\n', thisFolder)
    % do work with path variable directing to each child folder.
end

[Image Analyst]

@Monalisa Chikezie I saw your edit but it doesn't look like you ever tried my solution. Why not? I tried it and it works. Will you try please it?

[Monalisa Chikezie]

@Image Analyst This works!! Thank you so much

[Monalisa Chikezie]

@Image Analyst I realized that (fprintf('Processing folder : "%s".\n', thisFolder) this line takes too long to run

[Image Analyst]

@Monalisa Chikezie when I enclose fprintf in tic and toc it shows this:

tic
fprintf('Processing folder : "%s".\n', thisFolder)
toc

Elapsed time is 0.000012 seconds.

but if 12 microseconds is too long for you to wait, then you can certainly comment out that line, though maybe you should cut down on the caffeine. 😄

[Monalisa Chikezie]

I think it may be for

k = 1:length(folderNames) this line. It has been running for over 2 hours. If you have a suggestion, I would appreciate it.

[Image Analyst]

What is your top level folder? If it's the root it may take a while to do the dir statement. Step through the code or put in tic and toc to see what's taking up all the time. Attach your actual m-file if you need more help.

[Monalisa Chikezie]

I tried using tic toc, but, it didn't work as the code refused to stop running. I had to uninstall and reinstall matlab but, still same

[Monalisa Chikezie]

it gets stuck once I start the first line of the for loop

[Image Analyst]

What is in folderNames? Is it empty?

Debugging in MATLAB | Doug's MATLAB Video Tutorials

[Monalisa Chikezie]

folderNames has the subfolders. Thanks for the video, I'd watch it

[Image Analyst]

Then when you step through it line by line, which line hangs?

[Monalisa Chikezie]

for k = 1:length(folderNames)

[Monalisa Chikezie]

It works now.