How to replace a certain part of file name

I am writing a small code to that goes through the overall directory scans for all files, and if any image file have not same name pattern it will change it.

    loc = 'File Directory';
    flist = dir([loc '*.png']);
    for ii = 1:1:length(flist)
    fname = flist(ii).name;  
    [~, fn, xt] = fileparts(fname);
    img = imread([loc fname]);
    idxs = strfind(fn, '_');
    label = str2double(fn(idxs(end)+1:end));
    if label ~= 0    
    label= 0;        
    ffname = fullfile(loc, num2str(label), fname); % full file name
    imwrite(img, ffname);
        continue;
    end

My all files have file names like "m_7_13_10" with 10 being constant at the end. I want to change the 10 at end to 0. File should be in the same directory. What I am missing any one?

Answer 1

[Guillaume]

Loading the images and saving them back again just to change a filename is a big waste of time. Just rename the files!

An efficient way to do that:

   loc = ...
   flist = dir(fullfile(loc, '*.png'));
   torename = endsWith({flist.name}, '_10.png');
   for file = flist(torename)'
       movefile(fullfile(loc, file.name), fullfile(loc, regexprep(file.name, '_10\.png', '_0.png', 'preservecase')));
   end

[Raja Bilal Rsb]

Thank you for your answer, the code is just a part of bigger code, that does further processing on images. That's why I loaded the images so that I can do all I want at once. I had around 168k images in a single directory that I am applying that code on. Also many files does not have the same last part. Still thank you for your answer.

[Guillaume]

Ok, if you want to load the image and rename them, it's more or less the same:

loc = ...
flist = dir(fullfile(loc, '*.png'));
torename = endsWith({flist.name}, '_10.png');
for file = flist(torename)'
   img = imread(fullfile(loc, file.name);
   %... further processing
   imwrite(img, regexprep(file.name, '_10\.png', '_0.png', 'preservecase'));
end

[Raja Bilal Rsb]

The code is still missing the important thing that not every time last part will not be same. it can be _10,_9,_8 from 0 to 10 can be any. It should convert all these to _0, and than convert the file to gray-scale and crop it to 28*28.