Read files from folder and subfolder

Hi all,

I intend to read multiple files in the for loop operation from the folder and subfolder, which got different file extensions. For instnace, the main folder (say Folder A) got .jpg fiels and subfolder A1 got .bmp files.

%% read files from folder A
for f = 1:1:1
    if (f>=1) && (f<=9)
        fname_strt = 'B0000' ;
    elseif (f>=10) && (f<=99)
        fname_strt='B000';
    elseif (f>=100) && (f<=999)
        fname_strt='B00';
    else
        fname_strt='B0';
    end
    fname_end = num2str(f);
    fname = strcat(fname_strt,fname_end,'.jpg');
    I=imread(fname);
G = imagesc(x,y,flipud(I));
G.AlphaData = 0.5;
hold on;

%%%%%%% read files from subfolder A1
   
    if (f>=1) && (f<=9)
        fname_strt = 'B0000' ;
    elseif (f>=10) && (f<=99)
        fname_strt='B000';
    elseif (f>=100) && (f<=999)
        fname_strt='B00';
    else
        fname_strt='B0';
    end
    fname_end = num2str(f);
    fname = strcat(fname_strt,fname_end,'.jpg');
    h=imread(fname);
H1 = imagesc(flipud(h));
H1.AlphaData = 0.5;
axis equal
hold on;
end

[Stephen23]

As an aside, you should replace all of that complex IF/ELSEIF/ELSE, NUM2STR, and STRCAT with this:

fname = sprintf('B%05d.vc7',j)

Answer 1

[Ameer Hamza]

You can use dir() and for-loop to iterate over files in a folder to process them. This link shows a general template: https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html. For example,

%% read files from folder A
files = dir('*.jpg');
for i = 1:numel(files)
    filepath = fullfile(files(i).folder, files(i).name);
    img = imread(filepath);
    % process the file
end

%% read files from subfolder A1
files = dir(fullfile('A1', '*.bmp'));
for i = 1:numel(files)
    filepath = fullfile(files(i).folder, files(i).name);
    img = imread(filepath);
    % process the file
end

[Turbulence Analysis]

Thanks, Ameer.

I have revised my parent code based on this.. Now, I can read files from folder and subfolder respectively..

[Ameer Hamza]

I am glad to be of help!

[Turbulence Analysis]

I have used this with differen extension files, But I ended with some error.

The command loadvec() will work only if format is loadvec ('.vc7') or loadvec ('.im7'), hence, I replaced the img = loadvec(files(i).name); instead of img = imread(filepath);.

This works perfectly for the files reading from Folder A, However, it throws error while reading file from subfolder A1. I guess, its due to filepath is not mentioned.

%% read files from folder A
files = dir('*.im7');
for i = 1:numel(files)
    filepath = fullfile(files(i).folder, files(i).name);
    img = loadvec(files(i).name);
    % process the file
end

%% read files from subfolder A1
files = dir(fullfile('A1', '*.vc7'));
for i = 1:numel(files)
    filepath = fullfile(files(i).folder, files(i).name);
    img1= loadvec(files(i).name);
    % process the file
end

[Ameer Hamza]

How is the function loadvec defined?

[Turbulence Analysis]

loadvec() is one of the functions in pivmat toolbox package. http://www.fast.u-psud.fr/pivmat/

It specially to read the files in .im7, .vc7 format.

[Ameer Hamza]

Can you show the complete error message? It might be some ussue with loadvec() function.

[Turbulence Analysis]

Here, it is..

It reads the .im7 file without any issue. But not .vc7 file (i.e. file inside subfolder A1). Since, I am not using loadvec(filepath), hence, it's still looking to read the file from folder A rather than folder A1. This is the reason it throws 'No file match.' error message..

Somehow, if we provide the filepath correctly, I guess it will read .vc7 files.

Error using loadvec (line 238)
No file match. 

[Ameer Hamza]

Oh! I get it. You are only passing the filename to loadvec(). What happens if you pass the complete path? Does it gives error? For example, in your code, write

filepath = fullfile(files(i).folder, files(i).name);
img1= loadvec(filepath);

[Turbulence Analysis]

Hi,

Just noticed one thing, if my folder is located, let say in D drive , in this case my filepath = D:\New folder\A1\B00001.vc7. Here, it works perfectly for both folder A and subfolder A1.

But If I read the file from my server, in that case filepath = \\Data\data_\New folder\A1\B00001.vc7. Here it throws error. The sad part is I have to read file from my server.. (Lol!!!)

[Ameer Hamza]

This is definitely some problem with loadvec(). As the error message indicate that error occurs on line 238, which is

if isempty(filename)

which means that filename somehow become empty. And if you look at lines before 238, you can see that the function is doing some processing on the variable 'filename'. You may add a breakpoint inside the loadvec() function and see what causes the filename to become empty.

[Turbulence Analysis]

While my file is loacted in my D drive, it becomes

loadvec ('D:\New folder\A1\B00001.vc7') and this is working perfectly..

However, if i read from my server, it will be

loadvec ('\\Data\data\New folder\A1\B00001.vc7'); Here comes the error..