Read files in a specific order
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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
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Accepted Answer
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
Luke Riddell
on 22 Jun 2021
Hi Stephen,
I've tried this but I get an error returning.
When using:
S = dir(fullfile(FinalFolderloc,'*.ASC'))
S = natsortfiles(S)
It returns the error in line with the natsortfiles function:
" Error using bsxfun
Non-singleton dimensions of the two input arrays must match each other.
mat(logical(bsxfun(@eq,vec,nmn).')) = fnm; % TRANSPOSE bug loses type (R2013b)"
Do you have any advice?
More Answers (1)
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
Stephen23
on 23 May 2018
Edited: Stephen23
on 23 May 2018
This is a very fragile solution, because it assumes that the files themselves were written in the same order as the data was recorded: this will break easily, e.g. any time a file is edited, or if the files are copied from one folder to another.
"Can we sort the name field from dir?"
Yes. See my answer to know how.
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