Read files in a specific order

83 views (last 30 days)
Isma_gp
Isma_gp on 23 May 2018
Edited: Stephen23 on 22 Jun 2021
Hi, I have a series of files named with a date, for every third hour i.e. "NUM_1985_6_4_0_0.dat", "NUM_1985_6_4_3_0.dat", "NUM_1985_6_4_6_0.dat" ,....., "NUM_1985_6_4_21_0.dat",......, "NUM_1985_6_10_21_0.dat", "NUM_1985_6_11_0_0.dat". I'm using the dir command before using the fopen command. Is there any option when using the dir command to be able to list the files on a specific order. I would like to read the files by dates, however, the dir command gives me a list of files where the first one is "NUM_1985_6_10_0_0.dat" following a different logic, where the number 1 goes first in the list.
Thanks

Accepted Answer

Stephen23
Stephen23 on 23 May 2018
Edited: Stephen23 on 18 Apr 2021
Download my FEX submission natsorfiles, which was designed to fix the exact problem that you are having. Use it to simply sort the output from DIR:
D = '.'; % folder path
S = dir(fullfile(D,'*.dat'));
S = natsortfiles(S); % alphanumeric sort by filename
for k = 1:numel(S)
F = fullfile(D,S(k).name)
... import/process file F
end
Here is natsortfiles used on your example filenames:
>> C = {'NUM_1985_6_4_0_0.dat';'NUM_1985_6_4_3_0.dat';'NUM_1985_6_4_6_0.dat';'NUM_1985_6_4_21_0.dat';'NUM_1985_6_10_21_0.dat';'NUM_1985_6_11_0_0.dat'};
>> C = C(randperm(numel(C))) % "random" order
C =
NUM_1985_6_11_0_0.dat
NUM_1985_6_4_0_0.dat
NUM_1985_6_4_21_0.dat
NUM_1985_6_4_3_0.dat
NUM_1985_6_4_6_0.dat
NUM_1985_6_10_21_0.dat
>> D = natsortfiles(C) % alphanumeric sort
D =
NUM_1985_6_4_0_0.dat
NUM_1985_6_4_3_0.dat
NUM_1985_6_4_6_0.dat
NUM_1985_6_4_21_0.dat
NUM_1985_6_10_21_0.dat
NUM_1985_6_11_0_0.dat
  4 Comments
Stephen23
Stephen23 on 22 Jun 2021
Edited: Stephen23 on 22 Jun 2021
@Luke Riddell: you seem to have found a bug in NATSORTFILES. I just uploaded a new version to FEX, please download it, try it, and let me know if it works as expected.

Sign in to comment.

More Answers (1)

Rik
Rik on 23 May 2018
You can sort the output or dir any way you like. See below for an example.
filelist=dir('NUM_*.dat');
dates=[filelist.datenum];
[~,order]=sort(dates);
filelist=filelist(order);
  3 Comments

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!