Natural-Order Filename Sort

Alphanumeric sort of filenames or filepaths, with customizable numeric format.

To sort the elements of a string/cell array use NATSORT:

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

To sort the rows of a string/cell array use NATSORTROWS:

http://www.mathworks.com/matlabcentral/fileexchange/47433-natural-order-row-sort

### Summary ###

Alphanumeric sort the text in a string/cell/structure array. Sorts the strings taking into account the values of any number substrings. Compare for example:

>> A = {'a2.txt', 'a10.txt', 'a1.txt'};
>> sort(A)
ans = 'a1.txt'  'a10.txt'  'a2.txt'
>> natsortfiles(A)
ans = 'a1.txt'  'a2.txt'  'a10.txt'

By default NATSORTFILES interprets all consecutive digits as integer numbers, the number substring recognition can be specified using a regular expression: see NATSORT for details.

NATSORTFILES does not perform a naive natural-order sort, but sorts the filenames and file extensions separately to ensure a dictionary sort, where shorter filenames always sort before longer ones. Likewise filepaths are split at each file-separator character, and each level of the file hierarchy is sorted separately.

### Example with DIR ###

P = 'C:\SomeDir\SubDir';
S = dir(fullfile(P,'*.txt'));
S = natsortfiles(S);
for k = 1:numel(S)
    F = fullfile(P,S(k).name)
end

### File Dependency ###

The natural-order sort is provided by the function NATSORT (File Exchange 34464). All of NATSORT's optional inputs are supported by NATSORTFILES.

### Examples ###

>> B = {'test2.m'; 'test10-old.m'; 'test.m'; 'test10.m'; 'test1.m'};
>> sort(B) % Wrong number order:
ans =
   'test.m'
   'test1.m'
   'test10-old.m'
   'test10.m'
   'test2.m'
>> natsortfiles(B) % Shorter names before longer:
ans =
   'test.m'
   'test1.m'
   'test2.m'
   'test10.m'
   'test10-old.m'

%% Directory Names:
>> C = {'A2-old\test.m';'A10\test.m';'A2\test.m';'A1\test.m';'A1-archive.zip'};
>> sort(C) % Wrong number order, and '-' sorts before '\':
ans =
   'A1-archive.zip'
   'A10\test.m'
   'A1\test.m'
   'A2-old\test.m'
   'A2\test.m'
>> natsortfiles(C) % Shorter names before longer:
ans =
   'A1\test.m'
   'A1-archive.zip'
   'A2\test.m'
   'A2-old\test.m'
   'A10\test.m'

>> D = {'A1\B', 'A+/B', 'A/B1', 'A=/B', 'A\B0'};
>> sort(D)
ans =   'A+/B'  'A/B1'  'A1\B'  'A=/B'  'A\B0'
>> natsortfiles(D)
ans =   'A\B0'  'A/B1'  'A1\B'  'A+/B'  'A=/B'

>> F = {'test_new.m'; 'test-old.m'; 'test.m'};
>> sort(F) % Note '-' sorts before '.':
ans =
    'test-old.m'
    'test.m'
    'test_new.m'
>> natsortfiles(F) % Shorter names before longer:
ans =
    'test.m'
    'test-old.m'
    'test_new.m'