autorename if saved file already exist

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Luca Cavazzana
Luca Cavazzana on 14 Jan 2012
Commented: Diaa on 16 Oct 2020
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)

Accepted Answer

Jan on 14 Jan 2012
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]);
if exist(FileName, 'file')
% Get number of files:
fDir = dir(fullfile(fPath, [fName, '*', fExt]);
fStr = lower(sprintf('%s*',;
fNum = sscanf(fStr, [fName, '%d', fExt, '*']);
newNum = max(fNum) + 1;
FileName = fullfile(fPath, [fName, sprintf('%d', newNum), fExt]);
save(FileName, 'Data');
Limitations: "FileNameInf.txt" and "FileNameNaN.txt" will cause troubles...
Consider, that:
exist(FileName, 'file')
replies TRUE for directories also.
Jan on 14 Jan 2012
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.

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More Answers (1)

Diaa on 1 Oct 2020
Edited: Diaa on 1 Oct 2020
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]);
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]);
Diaa on 16 Oct 2020
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.

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