Why can't I use a variable to put all .txt files in a directory into an array?

Hllo!

I'm trying to use the following code to make an array of all .txt files in a specified directory to be later used by another script.

Here's the script that I'm working on

clc
clear 
clear all
  
rootfolder = 'T:\Data\';
Chopped = '\Chopped';
prompt = 'Enter date of experiment to be analyzed: ';
DataDate = input(prompt, 's');
Directory = strcat(rootfolder,DataDate,Chopped);

cd(Directory);
FilesToRead=dir;
for K = 1 : length(FilesToRead)
  thisfilename = FilesToRead(K).name;  %just the name
  %read the  file data
  %do something with the data
end

I have 18 datafiles in the folder I'm working with.

I'm getting a 20x1 structure. 18 of the data points are after '.' and '..'.

If I change k=1:length(FilesToRead) to 3:length(FilesToRead), I get no change in results.

when I change

FilesToRead=dir;

to

FilesToRead=dir(*.txt)

I get a 0x1 structure with nothing.

dir x00.txt

I get an output of the answer.

Following the MathWorks suggestion of pulling out folders with specific extensions,

List all files with a .m extension that contain the term my.

Create a folder, myfolder, that contains the files myfile1.m, myfile2.m, and myfile3.txt.

  mkdir myfolder
  movefile myfile1.m myfolder
  movefile myfile2.m myfolder
  movefile myfile3.txt myfolder

List the matching files in myfolder.

  cd myfolder
  dir *my*.m
  myfile1.m  myfile2.m    

When I type in

  cd(Directory);

I get the correct directory

If I type in dir x000.txt,

I get the correct file name output.

if I type in

  FilesToRead=dir;

I get the correct answer of all data files in the folder, as well as '.' and '..'

If I type in

dir *x*.txt

I get no results.

Variables are not working and I don't know why. This is the exact same format as mathworks.

I'm lost

[Walter Roberson]

FilesToRead=dir('*.txt');

Provided that there are .txt files in that directory.

Answer 1

[Walter Roberson]

rootfolder = 'T:\Data';
Chopped = 'Chopped';
prompt = 'Enter date of experiment to be analyzed: ';
DataDate = input(prompt, 's');
Directory = fullfile(rootfolder, DataDate, Chopped);
FilesToRead = dir(Directory);
FilesToRead([filesToRead.isdir]) = [];
filenames = fullfile(Directory, {FilesToRead.name});
for K = 1 : length(filenames)
  thisfilename = filenames{K};    %fully qualified filename
  %read the  file data
  %do something with the data
end

Answer 2

[Adam Danz]

Here's a bunch of feedback.

1) don't use "clear all". Here's why: link.

clc
clear 
% clear all  % avoid doing this.

2) instead of relying on the user to enter the correct date in the correct format in hopes that it leads to an existing path, use the uigetdir() function which will allow the user to select the directory directly.

rootfolder = 'T:\Data\';
Chopped = '\Chopped';
prompt = 'Enter date of experiment to be analyzed: ';
DataDate = input(prompt, 's');
Directory = strcat(rootfolder,DataDate,Chopped);

% Instead,
Directory = uigetdir(rootfolder);

3) don't change the CD. Instead, specify the directory in the dir() input. (see Walter's answer to select relevant files)

cd(Directory);
FilesToRead=dir;

% Instead, 
FilesToRead = dir(Directory); 

4) Skip elements in "FilesToRead" that aren't files. (see Walter's answer to select relevant files)

for K = 1 : length(FilesToRead)
    if FilesToRead(k).isdir        % % % % % % % % % % %
        continue                   %    ADD THIS       %
    end                            % % % % % % % % % % % 
  thisfilename = FilesToRead(K).name;  %just the name
  %read the  file data
  %do something with the data
end

[EL]

I can't use uigetdir because this is being run through linix through command line.

I'll let you know how this works when I get home and get some time

[Adam Danz]

I've never used linix but is the problem related to this bug?

https://www.mathworks.com/matlabcentral/answers/97271-why-am-i-unable-to-select-a-directory-in-the-browse-directory-dialog-displayed-by-the-uigetdir-fun

[EL]

Uigetdir needs a gui to operate. I'm ssh'ing to a linux system and processing data renotely through command line. Besides, the date is a simple ddmmyyyy format to select he correct folder. I won't mess it up.

[Adam Danz]

ah, OK then. You could use exist(Directory ,'dir') to confirm that the directory exists or check if the dir output is empty.

FilesToRead = dir(Directory); 
if isempty(FilesToRead)
    error('Directory does not exist: %s', Directory)
end