how to rename images using a loop?

Hello. I have 150 images (images_0, images_1, images_2, ......, images_140) which are saved in 4 folders called : dataset_1, dataset_2, dataset_3 and dataset_4.

I use this code to rename images

mainDirectory = 'C:\Users\Desktop\data';
subDirectory = dir([mainDirectory '/dataset_*']);
for m = 1 : length(subDirectory)
  subFolder = dir(fullfile(mainDirectory, subDirectory(m).name,'*.png'));  
  fileNames = {subFolder.name};  
  for iFile = 1 : numel( subFolder )    
    newName = fullfile(mainDirectory, subDirectory(m).name, sprintf('%00d.png',(iFile) ) );
    movefile( fullfile(mainDirectory, subDirectory(m).name, fileNames{ iFile }), newName );
  end
end

This code works well, but I'm new in MATLAB and I want to change the newName as follows : (number of the dataset)_(name of the image)

For example : 1_images_0, 1_images_1, 2_images_0, 2_images_1, ...

Please, any idea how can I change the newName to rename the images? Please help me and thanks in advance.

[jgg]

I'm not 100% clear on how your code works, but I think the easiest way would be to just concatenate the strings.

Inside the iFile = 1 loop:

 newFileName = strcat(num2str(m), '_images_', num2str(iFile),'.png');
 newName = fullfile(mainDirectory, subDirectory(m).name, newFileName);

Does that do what you intended? The '_images_','.png' part is hardcoded in this example for clarity, but you could replace it with fileNames{ iFile } and remove the last part if you want to be more flexible.

[souha abdalah]

it not work, that is not the solution that I want.

[Geoff Hayes]

Why doesn't the solution from jgg not work as expected or isn't the solution that you want? An alternative is to just replace your sprintf call

 sprintf('%00d.png',(iFile) )

with

 sprintf('%d_images_%00d.png',m,iFile);

[souha abdalah]

No, this is not the solution. when I use "sprintf('%d_images_%00d.png',m,iFile);", the result is wrong, for example the folder dataset_2, the names of the images are: 4_images_1 .... then the result must be 2_images_1

[jgg]

Sorry, I'm not clear what's wrong with the solution I suggested? Are your folders not arranged in order (so dataset 2 is folder 4 for instance?). If so, you should be able to easy adjust the code I gave with a simple lookup matrix.

[Geoff Hayes]

Or just remove the dataset_ portion and convert the remainder to a string. For example,

 folderName = 'dataset_42';
 folderId   = str2num(strrep(folderName,'dataset_',''));

Or use regexp to do something similar.

Answer 1

[Image Analyst]

This will do it:

% Start with a folder and get a list of all subfolders.
% Finds and prints names of all files in 
% that folder and all of its subfolders.
% Similar to imageSet() function in the Computer Vision System Toolbox: http://www.mathworks.com/help/vision/ref/imageset-class.html
clc;    % Clear the command window.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;

% Define a starting folder.
start_path = pwd;  % %'C:\Users\Desktop\data';
if ~exist(start_path, 'dir')
  start_path = matlabroot;
end
% Ask user to confirm or change.
uiwait(msgbox('Pick a starting folder on the next window that will come up.'));
topLevelFolder = uigetdir(start_path);
if topLevelFolder == 0
  return;
end
% Get list of all subfolders.
allSubFolders = genpath(topLevelFolder);
% Parse into a cell array.
remain = allSubFolders;
listOfFolderNames = {};
while true
  [singleSubFolder, remain] = strtok(remain, ';');
  if isempty(singleSubFolder)
    break;
  end
  listOfFolderNames = [listOfFolderNames singleSubFolder];
end
numberOfFolders = length(listOfFolderNames)

% Process all image files in those folders.
for k = 1 : numberOfFolders
  % Get this folder and print it out.
  thisFolder = listOfFolderNames{k};
  fprintf('Processing folder %s\n', thisFolder);

  % Get ALL files in this folder.
  filePattern = sprintf('%s/*.*', thisFolder);
  baseFileNames = dir(filePattern);
  
  numberOfImageFiles = length(baseFileNames);
  if numberOfImageFiles >= 1
    % Go through all those files.
    for f = 1 : numberOfImageFiles
      existingFullFileName = fullfile(thisFolder, baseFileNames(f).name);
      if isdir(existingFullFileName)
        % Skip folders . and ..
        continue;
      end
      % Get the last character of the folder.  It should be a number from 1 to 4.
      lastDigit = thisFolder(end);
      % Create a new name for it.
      newBaseFileName = sprintf('%s_images_%d.png', lastDigit, f-1);
      newFullFileName = fullfile(thisFolder, newBaseFileName);
      fprintf('     Renaming file %s to %s\n', existingFullFileName, newFullFileName);
      % Do the actual renaming.
      movefile(existingFullFileName, newFullFileName);
    end
  else
    fprintf('     Folder %s has no files in it.\n', thisFolder);
  end
end

[souha abdalah]

thank you very much for your answer, it works for this example. but when I used an other database that contains 14 files (14 dataset), I did not get the right result. the program running until the 9 first datasets but then it renames pictures from 0 as here:

 1_images_1,......
2_images_1,......
3_images_1,......
4_images_1,......
5_images_1,......
6_images_1,......
7_images_1,......
8_images_1,......
9_images_1,......

 % the error begin here
0_images_1,......% but the right name : 10_images_1,......
1_images_1,......% but the right name : 11_images_1,......
2_images_1,......% but the right name : 12_images_1,......
3_images_1,......% but the right name : 13_images_1,......
4_images_1,......% but the right name : 14_images_1,......

please help me how do it?

[Image Analyst]

Get the number from after the "dataset_" like this

% Get the string from after the "dataset_"
% It should be an integer number.  
% Use str2double() to get it as a number.
lastDigits = str2double(thisFolder(9:end));
% Create a new name for it.
newBaseFileName = sprintf('%d_images_%d.png', lastDigits, f-1);

Note how I used %d instead of %s in sprintf() now that lastDigits is a number not a single character.

[souha abdalah]

I'm sorry for the late reply but when I used this code. the name of the images become:

 NaN_images_1
 NaN_images_2
 NaN_images_3
 NaN_images_4
........................

how can I correct this problem please and thanks in advance

[Image Analyst]

Replace this line

lastDigits = str2double(thisFolder(9:end));

with these

fprintf('Folder = %s\n', thisFolder);
fprintf('The last digits = %s\n', thisFolder(9:end));
lastDigits = str2double(thisFolder(9:end));
fprintf('That converts to %d.\n', lastDigits);

What do you learn in the command window? What does it print out? I think thisFolder must not have the format you said it did.

[souha abdalah]

I found the same result, a part of the output command window is in the attached picture.

according to you, what is the problem?

[Image Analyst]

Try this:

% Start with a folder and get a list of all subfolders.
  % Finds and prints names of all files in 
  % that folder and all of its subfolders.
  % Similar to imageSet() function in the Computer Vision System Toolbox: http://www.mathworks.com/help/vision/ref/imageset-class.html
  clc;    % Clear the command window.
  workspace;  % Make sure the workspace panel is showing.
  format long g;
  format compact;

    % Define a starting folder.
    start_path = 'd:\data';  % %'C:\Users\Desktop\data';
    if ~exist(start_path, 'dir')
      start_path = matlabroot;
    end
    % Ask user to confirm or change.
    uiwait(msgbox('Pick a starting folder on the next window that will come up.'));
    topLevelFolder = uigetdir(start_path);
    if topLevelFolder == 0
      return;
    end
    % Get list of all subfolders.
    allSubFolders = genpath(topLevelFolder);
    % Parse into a cell array.
    remain = allSubFolders;
    listOfFolderNames = {};
    while true
      [singleSubFolder, remain] = strtok(remain, ';');
      if isempty(singleSubFolder)
        break;
      end
      listOfFolderNames = [listOfFolderNames singleSubFolder];
    end
    numberOfFolders = length(listOfFolderNames)

    % Process all image files in those folders.
    for k = 1 : numberOfFolders
      % Get this folder and print it out.
      thisFolder = listOfFolderNames{k};
      fprintf('Processing folder %s\n', thisFolder);

      % Get ALL files in this folder.
      filePattern = sprintf('%s/*.*', thisFolder);
      baseFileNames = dir(filePattern);
      
      numberOfImageFiles = length(baseFileNames);
      if numberOfImageFiles >= 1
        % Go through all those files.
        for f = 1 : numberOfImageFiles
          existingFullFileName = fullfile(thisFolder, baseFileNames(f).name);
          if isdir(existingFullFileName)
            % Skip folders . and ..
            continue;
          end
          % Get the last character of the folder.  It should be a number from 1 to 4.
          lastDigit = thisFolder(end);
          % Get the base file name
        [folder, baseFileName, ext] = fileparts(existingFullFileName);
          % Create a new name for it.
          newBaseFileName = sprintf('%s_%s%s', lastDigit, baseFileName, ext);
          newFullFileName = fullfile(thisFolder, newBaseFileName);
          fprintf('     Renaming file %s to %s\n', existingFullFileName, newFullFileName);
          % Do the actual renaming.
           movefile(existingFullFileName, newFullFileName);
        end
      else
        fprintf('     Folder %s has no files in it.\n', thisFolder);
      end
    end

[souha abdalah]

Unfortunately, when I tested the latter code. the result is true only for these folders(1 to 9) but for others folder (10 to 14), the result is

0_SentenceImage_0, 0_SentenceImage_1
1_SentenceImage_0, 1_SentenceImage_1
2_SentenceImage_0, 2_SentenceImage_1
3_SentenceImage_0, 3_SentenceImage_1
4_SentenceImage_0, 4_SentenceImage_1

the used database is attached. please, can you specify exactly what is the error? and thanks in advance.

[Image Analyst]

Originally you said it only went up to 4 but now you say it can go past 9 and be two or more digits. The code I wrote was for what you said originally. If you want a more general solution, then replace this line

% Get the last character of the folder.  It should be a number from 1 to 4.
lastDigit = thisFolder(end);

with this code to extract everything after the underline.

% Get the last characters of the folder, after the only underline.
%  It should be a number.
underlineLocation = strfind(thisFolder, '_');
lastDigit = thisFolder((underlineLocation +1):end);

Of course this will also fail if you present thisFolder that has no underlines or more than 1 underline. You'd need more code to detect and handle those situations.

[souha abdalah]

thank you very much, that is the solution that I'm looking for