How to delete files ending with odd number?

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Morgane Flament 2018-8-13

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评论： Morgane Flament 2018-8-13

Hi,

I would like to delete each files having its filename ending by an odd number. Example: file0 file1 file2 file3 file4 After: file0 file2 file4

Thank you for your help :)

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Answer 1

Simon Henin 2018-8-13

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https://ww2.mathworks.cn/matlabcentral/answers/414691-how-to-delete-files-ending-with-odd-number#answer_332617

编辑：Simon Henin 2018-8-13

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You could looop through all the files and delete ones that have an odd number using regexp, regular expression search

files = dir('*'); % find all files in current directory
for i=1:length(files),
  fileno = str2double(cell2mat(regexp(files(i).name, '[0-9]{1,}', 'match')));
  if mod(fileno, 2) == 1, % check if fileno modulo 2 == 1
    delete(files(i).name);
  end
end

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Simon Henin 2018-8-13

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That won't work, because files(i).name file was just deleted.

The main thing you should worry about is overwriting a file, since dir command will usually sort files by the leading digit. for example: file1.ext file11.ext file2.ext ...

This is what I would do:

pth = '/path/to/folder/containing/files/';
files = dir([pth 'file*']);
for i=1:length(files),
    fileno = str2double(cell2mat(regexp(files(i).name, '[0-9]{1,}', 'match')));
    if mod(fileno, 2) == 1, % check if number, and if fileno % 2 == 1
        delete([pth files(i).name]);
    else
        % temporarily rename kept files, to avoid overwriting in the next step
        newfile = ['tmp_' files(i).name]; 
        movefile([pth files(i).name], [pth newfile]);
    end
end
% now loop through all the tmp_file* files and rename them using an
% the incremented counter, i
files = dir([pth 'tmp_file*']);
for i=1:length(files),
     % remove the tmp_ and replace the numbers at the end using regexprep
     newfile = regexprep(files(i).name, {'tmp_' '[0-9]{1,}'}, {'' sprintf('%02i', i)}); % will change "tmp_fileXX.ext" -> "file01.ext"
     movefile([pth files(i).name], [pth newfile]);
end

Simon Henin 2018-8-13

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No, it could be done within the same loop (with proper accounting). It is just much easier to use a separate loop to make sure nothing gets overwritten.

Simple example.

Imagine:

files = {'file1', 'file2', 'file22', file24', file3'}; % this will happen because of how the dir command organizes the returned files
counter = 1;

----

Each time you go through the loop:

1) file1 will be deleted
2) file2 -> file1
3) file22 -> file2
4) file24 -> file3 (here's the issue. file3 hasn't gone through the loop yet, and thus, will be overwritten!)

---

Hope this clear it up.

Morgane Flament 2018-8-13

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Thank you very much for your help Simon. It is all clear.

I was also thinking of sorting the files using the function NATSORTFILES: (https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort)

pth = '/path/to/folder/containing/files/';
files = dir(fullfile(pth,'file*')); % Get the file in the directory
N = natsortfiles({files.name}); % Sort the filename in natural order
for k = 1:numel(N) 
    fullfile(D,N{k}) 
end

And then I add the loops. Do you think it is a good idea?

Again, thank you for your time, it helps me a lot.

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Answer 2

Morgane Flament 2018-8-13

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@Simon Henin, do you think I can use your code as well, to delete each file ending with number 2, 3, 4, 5, but not with 0 and 1 let's say? (so no function with odd/even number in this case, I would like to delete the file based on its number at the end of the filename).