Natural-Order Filename Sort

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

To sort all of the strings in a cell array use NATSORT:
http://www.mathworks.com/matlabcentral/fileexchange/34464-customizable-natural-order-sort
To sort the rows of a cell array of strings use NATSORTROWS:
http://www.mathworks.com/matlabcentral/fileexchange/47433-natural-order-row-sort

### Summary ###

Alphanumeric sort of a cell array of strings (1xN char). Sorts the strings taking into account the values of any number substrings occurring within those strings. 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 and Cell Array ###

D = 'C:\Test';
S = dir(fullfile(D,'*.txt'));
N = natsortfiles({S.name});
for k = 1:numel(N)
fullfile(D,N{k})
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 = {'test_new.m'; 'test-old.m'; 'test.m'};
>> sort(B) % Note '-' sorts before '.':
ans =
'test-old.m'
'test.m'
'test_new.m'
>> natsortfiles(B) % Shorter names before longer (dictionary sort):
ans =
'test.m'
'test-old.m'
'test_new.m'

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

%% Directory Names:
>> D = {'A2-old\test.m';'A10\test.m';'A2\test.m';'A1archive.zip';'A1\test.m'};
>> sort(D) % Wrong numeric order, and '-' sorts before '\':
ans =
'A10\test.m'
'A1\test.m'
'A1archive.zip'
'A2-old\test.m'
'A2\test.m'
>> natsortfiles(D) % Shorter names before longer (dictionary sort):
ans =
'A1archive.zip'
'A1\test.m'
'A2\test.m'
'A2-old\test.m'
'A10\test.m'