MATLAB: Sort the dir loaded files

dir

I am using

imagefiles = dir(fullfile(d, '*.jpg'));

to get the jpg images in a folder that are named numerically like 1.jpg, 2.jpg, …

I noticed that they are not loaded with their order like 1.jpg, 2.jpg, 3.jpg, … and they are just randomly loaded like 1.jpg, 10.jpg, 2.jpg, …

How can I load them with an order

Best Answer

Construct the file names instead of reading them.

Or construct better file names when you write them -- use leading 0's in the name.

Or look in the File Exchange for "Natural Directory Sort"

Related Solutions

MATLAB: Looping to read image

My File Exchange submission natsortfiles was written exactly for solving this problem:

http://ww.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

It sorts a cell array of strings into the order that you require, by considering all numeric values in the strings instead of just the naive character order (like sort does). You can use it very simply:

>> B = {'test2.m'; 'test10-old.m'; 'test.m'; 'test10.m'; 'test1.m'};
>> natsortfiles(B)
ans =
  'test.m'
  'test1.m'
  'test2.m'
  'test10.m'
  'test10-old.m'

whereas the inbuilt sort returns the strings sorted according to their character order:

>> sort(B)
ans =
  'test.m'
  'test1.m'
  'test10-old.m'
  'test10.m'
  'test2.m'

To use this with your filenames, simply extract the filename strings from the output of dir like this:

hasil = dir('*.jpg');
names = natsortfiles({hasil.name});
for k = 1:numel(names)
    out = imread(names{k});
    ... image processing here
end

Note that natsortfiles is a wrapper for this function, which you will also need:

http://www.mathworks.com/matlabcentral/fileexchange/34464-customizable-natural-order-sort

MATLAB: Dir sorts filenames wrong

"what can i do?"

If the filenames contain sufficient leading zeros, then split the names using fileparts, then sort the names, e.g.:

S = dir(....);
C = {S.name};
[~,F] = cellfun(@fileparts,C,'uni',0);
[~,X] = sort(F);
C = C(X);

Tested on some sample filenames:

>> C = {'Data2F.Part010.mdf','Data2F.Part003.mdf','Data2F.Part009.mdf','Data2F.mdf'};
>> [~,F] = cellfun(@fileparts,C,'uni',0);
>> [~,X] = sort(F);
>> C = C(X);
>> C{:}
ans = Data2F.mdf
ans = Data2F.Part003.mdf
ans = Data2F.Part009.mdf
ans = Data2F.Part010.mdf

Otherwise you can download my FEX submission natsortfiles and use it to sort the filenames (it splits the file extension for you, and also takes into account any number values in the names):

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

The submission includes help and HTML documentation with plenty of examples, you would probably need something a bit like this:

S = dir(....);
C = natsortfiles({S.name});

Note that with either sort or natsortfiles you can obtain the sort indices, to sort the structure with:

S = dir(...);
[~,X] = natsortfiles({S.name}); % or SORT
S = S(X);

Best Answer

Related Solutions

MATLAB: Looping to read image

MATLAB: Dir sorts filenames wrong

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