autorename if saved file already exist

is there an option in save (or any other function) which support automatic renaming if the filename already exists or do I need to check by myself? (like saving as file2.mat if file.mat already exist)

[Stephen23]

https://blogs.mathworks.com/pick/2020/01/10/determining-next-available-file-name/

https://www.mathworks.com/matlabcentral/fileexchange/64108-next-available-filename

Answer 1

[Jan]

You have to check it by your own if a file is existing already.

[EDITED: Consider {File.txt, File3.txt}]

function SaveWithNumber(FileName, Data)
[fPath, fName, fExt] = fileparts(FileName);
if isempty(fExt)  % No '.mat' in FileName
  fExt     = '.mat';
  FileName = fullfile(fPath, [fName, fExt]);
end

if exist(FileName, 'file')
  % Get number of files:
  fDir     = dir(fullfile(fPath, [fName, '*', fExt]);
  fStr     = lower(sprintf('%s*', fDir.name);
  fNum     = sscanf(fStr, [fName, '%d', fExt, '*']);
  newNum   = max(fNum) + 1;
  FileName = fullfile(fPath, [fName, sprintf('%d', newNum), fExt]);
end
save(FileName, 'Data');

Limitations: "FileNameInf.txt" and "FileNameNaN.txt" will cause troubles...

Consider, that:

exist(FileName, 'file')

replies TRUE for directories also.

[Image Analyst]

Other options could be alerting the user that the file exists and to either

(1) Cancel (Skip it),

(2) Overwrite with the same name, or

(3) Use the new name determined by Jan's nice function, or

(4) call uiputfile to let the user supply a name.

You could use menu() to present the user with those options.

[Jan]

My "nice" function is too lazy: Imagine these files are existing already: File.txt, File3.txt. Now the user wants to save File.txt - now the function tries to create File3.txt and fails recursively.

I'm posting a new version, which is hopefully smarter.

Answer 2

[Diaa]

Revisitng this old question, I followed the idea of Jan to come up with this solution of appending the existent file name with an incremental number enclosed in parentheses.

if exist(filename,'file')
    [fPath, fName, fExt] = fileparts(filename);
    fDir = dir(fullfile(fPath, [fName,' (*)', fExt]));
    if isempty(fDir)
        filename = fullfile(fPath, [fName,' (1)', fExt]);
    else
        pattern = "(" + digitsPattern + ")" + fExt;
        hasThePattern = endsWith(extractfield(fDir,'name'),pattern);
        Extracted = extract(extractfield(fDir(hasThePattern),'name'),pattern);
        num = max(cell2mat(cellfun(@(C) textscan(C,'(%d)') , Extracted,'UniformOutput',true)));
        num = num+1;
        filename = fullfile(fPath, [fName,' (',num2str(num),')', fExt]);
    end
end

[Joshua Grosserhode]

Nice clean solution. Since I do not yet have 2020b, I used this solution:

num = 0;
while exist(FileName, 'file')

num = num+1;
FileName = fullfile(outFolder, [fName,' (',num2str(num),')', fExt]);            

end

[Diaa]

Nice and consice approach but it will intuitively fail when you have in your folder

file name
file name (1)
file name (3)

as your code will create a new file

file name (2)

with a number smaller than the existent max one (i.e. 3), and hence it will mislead the user to make him/her think the file name (3) is newer, which is not.

[Mohammed Attrash]

You can add to your file name the following

datestr(now,'dd.mm.yyyy_HH.MM')

This will create a unique name

[Walter Roberson]

@Mohammed Attrash

It can sometimes be important to preserve the file extension, so make sure that is added before the extension.

These days it is better to use

string(datetime('now', 'format', 'uuuu.MM.dd_HH.mm'))

ans = "2023.07.09_08.27"