How to rename multiple files in a folder with variable names depending on their names in another folder?

I have several files in a directory (some examples of the names of the files are commented under the commented word (oldnames)), and I want to rename them as the commented ones ( under the commented word (newnames)). So I want to extract every number that has 4 digits (e.g., (3185)) and use it to rename the new files. I tried to extract the numbers that have 4 digits as below but it didn't work. Any suggesstions?

projectdir = 'C:\Users\Abdelrahman\Downloads\Documents\CIV312_Test';
oldfiles = dir( fullfile(projectdir, '*3*.pdf') );
oldnames = {oldfiles.name};

myindices = cellfun(@isempty,regexp(oldnames,'*3\d\d\d*','match'));  % didn't work

% oldnames
% (CIV-312-3154)_Template.pdf
% 3140_CIV312.pdf
% CIV _312_3085.pdf
% CIV-312-3051.pdf

% newnames
% CIV_312_3154.pdf 
% CIV_312_3140.pdf
% CIV_312_3085.pdf
% CIV_312_3051.pdf

Answer 1

[Mohammad Sami]

You dont need the *. you can do as follows.

match = regexp(oldnames,'3\d{3}','match');

[Abdel-Rahman Ashraf]

Thank you for your answer. Yes, it worked but how to store these numbers so that I reuse them in renaming the folders?

[Mohammad Sami]

The variable match will contain the string that matched.

Assuming that you match only once.

match = regexp(oldnames,'3\d{3}','match','once');
missing = cellfun(@isempty,match);
match2 = match(~missing);

[Abdel-Rahman Ashraf]

Many thanks. So the last part is to rename them. I did the follwing but it is not correct. I would be grateful for your help if you can tell me what to do.

 projectdir = 'C:\Users\Abdelrahman\Downloads\Documents\CIV312_Test';
   
  
   oldfiles = dir( fullfile(projectdir, '*3*.pdf') );
   oldnames = {oldfiles.name};
   
   match = regexp(oldnames,'3\d{3}','match','once');
   missing = cellfun(@isempty,match);
   match2 = match(~missing);
   
   for i= 1 : length(match2)
   newnames = regexp(oldnames,oldnames(i),'CIV_312_match2(i)');
   end

[Mohammad Sami]

regexp is for matching, to create a new string, there are various options. One of the option is to use the compose function since you are following a template name.

newnames = compose('CIV_312_%s.pdf',string(match2));

[Abdel-Rahman Ashraf]

Thank you very much for your help, Mohammad. Here is my final version of what I wanted in case anyone faced such a problem in the future.

   % The directory of the files
   projectdir = 'C:\Users\Abdelrahman\Downloads\Documents\CIV312_Test';
   % The directory of the renamed files
   projectdir1 = 'C:\Users\Abdelrahman\Downloads\Documents\CIV312_Test\XX';
  
   
   oldfiles = dir( fullfile(projectdir, '*.pdf') );
   oldnames = {oldfiles.name};
   
   % Replace '3\d{3}' with the first digit of the codes of the students
   % For example, if the codes of students are from 5400 to 5413, replace
   % '3\d{3}' with '5\d{3}'
   % Notice that '3\d{3}' is found in variables 'match' and 'myindices'. So
   % replace both of them.
   match = regexp(oldnames,'3\d{3}','match','once');
   missing = cellfun(@isempty,match);
   myindices = ~cellfun(@isempty,regexp(oldnames,'3\d{3}','match'));
   
   
   for i= 1 : length(match)
   if  myindices(i)
      match1(i)= match(i); 
   else
      match1{i} =  strcat('unknown',num2str(i));
   end
   end  
   
   
   % Replace 'CIV_312_' with the code of the course 
   newnames= strcat('CIV_312_',match1,'.pdf') ;
   
   for K = 1 : length(oldnames)
      movefile( fullfile(projectdir, oldnames{K}), fullfile(projectdir1, newnames{K}) );
   end