Order of filenames is wrong

Hello,

I have save some measures in loop with

SNR = 30

SNR_steps = 15

-SNR:SNR_steps:SNR
ans =   -30   -15     0    15    30

I use SNR also in part of the filename and I get:

The Problem: the order of files in the folder is (-015 before -030), but I want to have -030, -015, 000, 015, 030...

Why is this happening, and how can I avoid this situation?

Thank you!

[Rik]

Because the sort happens on the text itself, not the meaning of that text.

So the solution is to change your OS to an OS that supports interpreting the dash as a negative sign.

Where do you want to use the file order?

[Nik Rocky]

Hello Rik, thank you for response!

I'm using ubuntu 16.04. And I need this fileorder by reading and plotting wich another MATLAB script.

For every value I get a row, in this case:

Measure_020 = 
    0.2112    0.3973 %< should be second row    
    0.0825    0.6542 %< should be first row
    0.5479    0.1426
    0.5818    0.1912
    0.5904    0.1303

I sort the data already with small script:

l = dir('**/*.mat');
for k = 1:length(l)
    [filepath,name,ext] = fileparts(l(k).name);
    Correct_Folder = l(k).folder;
    Correct_Name = l(k).name;
    Correct_Folder_Name = fullfile(Correct_Folder,Correct_Name);
    load(Correct_Folder_Name)
    disp(Correct_Name)
    temp = M(1,:);
    M(1,:)=M(2,:);
    M(2,:)=temp;
    save(Correct_Folder_Name)
end

but how can I avoid it i future?

[Rik]

Use the function suggested in the answer below to read the filenames in the order that fills your array in the order that makes sense to you.

Answer 1

[KSSV]

Use this fileexchange function:

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

[Image Analyst]

Not sure it will work, but there are lots of options with it to try

https://blogs.mathworks.com/pick/2014/12/05/natural-order-sorting/

[Stephen23]

Note that a suitable regular expression will have to be provided as the second input argument, as by default natsortfiles uses the natsort default of matching digits only (i.e. positive integers including zero). For example:

'[-+]?\d+'

or in case you only need to match that one number:

'[-+]?\d+(?=_PLL)'

You should also return its third output argument to confirm that the required numbers are being correctly converted to numeric.