Loading variables from different folders containing subfolders in loop

Hello,

I have 39 folders, each of them containing 6 subfolders with mat files inside in the form of a matrix mxn. From the matfiles, I need to load the matrices with the lowest n of zeros in a loop and save them in a mat.file in the workspace so that those can be loaded when it is necessary to save variables in them.

Any suggestion on how to do that?

Thank you!

[Stephen23]

Use DIR with the '**' syntax to get a structure of all of the files:

https://www.mathworks.com/help/matlab/ref/dir.html

Loop over that structure. Perform whatever check or comparison you need inside the loop.

[Eleonora Montagnani]

Hi Stephen. It worked thanks for the suggestion.

Now I would need to find the matrices within each subfolder containing the higher n of zeros (which I will call templates). Although I know this is straightforward to do, the problem I am finding is to make them "recognisable" as templates when I run the loop. In other words, I need to save something called let's say "template" in the files representing the template so that when I need them I can load them and perform my analysis. Any tip to do so?

Thanks again

[Stephen23]

@Eleonora Montagnani: it sounds like you probably just need to store the imported data in an array. One approach is to use a cell array, as shown in the MATLAB documentation:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

Another simple and versatile approach is to use the structure returned by DIR:

P = 'absolute or relative path to the root directory',
S = dir(fullfile(P,'**','*.mat'));
for k = 1:numel(S)
    F = fullfile(S(k).folder,S(k).name);
    D = load(F);
    .. decide what data you want to store
    S(k).somedata = whatever_you_want_to_store;
    S(k).otherdata = something_else;
end

Then you can use another loop to compare those matrices and perform your analyses.

[Eleonora Montagnani]

Thank you!

Answer 1

[Mathieu NOE]

hello

an example below to show how to loop over directories and load in natural sorting ordre the files in each folder

clc
clearvars

%% define path
yourpath = pwd; % or your specific path
list=dir(yourpath);  %get info of files/folders in current directory
isfile=~[list.isdir]; %determine index of files vs folders
dirnames={list([list.isdir]).name}; % directories names (including . and ..)
dirnames=dirnames(~(strcmp('.',dirnames)|strcmp('..',dirnames))); % remove . and .. directories names from list

%% demo for excel files
sheet = 1; % specify which sheet to be processed (my demo) - if needed

%% Loop on each folder
for ci = 1:length(dirnames) % 
    fileDir = char(dirnames(ci)); % current directory name
    S = dir(fullfile(fileDir,'Sheeta*.xlsx')); % get list of data files in directory according to name structure 'Sheeta*.xlsx' 
    S = natsortfiles(S); % sort file names into natural order (what matlab does not) , see FEX : 
               %(https://fr.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort)

    %% Loop inside folder
    for k = 1:length(S) % read data in specified sheet
        data = xlsread(fullfile(fileDir, S(k).name),sheet); % or use a structure (S(k).data ) to store the full data structure
        % your own code here for data processing. this is just for my demo
        % for now :
        title_str = [fileDir ' / ' S(k).name ' / sheet : ' num2str(sheet)];
        figure,plot(data),title(title_str);
    end
        
end