Data in subfolder cannot be load

Hello, I'm using Matlab R2015b and having problem in reading all data from few sub folders. The folder/dir can be detected but it do not read/extract my data which is in form of '.DATA' and it is quite large data files. In each .DATA, the data is separated with space. I try to fix my coding but still the data cannot be read. I hope anybody can help me on where should i fix my code. I appreciate any help from you guys, thanks.

Here is the code:

 f=dir(strcat(folderdir,'*.DATA'));

    p={f.name};  
    temp = {};

    for k=1: numel(p)
      file= strcat(folderdir,p{k});
      fid=fopen(file);
      b=textscan(fid,'%f %f %f','delimiter',' ');
      fclose(fid);
      x=b{1};
      y=b{2};
      z=b{3};
      data{k}=dataset(x,y,z);
      temp{k}=data{k}; 
    end
    set{j-2} = temp;
    setname{j-2} = foldername;  
end

Answer 1

[Walter Roberson]

We recommend using fullfile(folderdir, '*.DATA') and fullfile(folderdir, p{k}) instead of strcat .

You should replace

fid=fopen(file);

with

 [fid, msg] = fopen(file, 'r');
 if fid < 0
    error('Cannot open file "%s" because "%s"', file, msg);
 end

[Nurul Atifah]

First of all, thanks for the reply. I had try to fix the code like what you have stated, it can run and no error but still the data cannot be read. Here is the code that i had fix as your advice and code of how i called the folder and subfolders to give you clear view of my code:

 files = dir('TrainingData');
dirFlags = [files.isdir];
subfolders = files(dirFlags);
for j = 3: length(subfolders)
    folder = fullfile(subfolders(j).name,'\');
    foldername = subfolders(j).name;

    folderdir = fullfile(files(1).name,'\',folder);

    f=dir(fullfile(folderdir, '*.DATA'));

    fil={f.name};  
    temp = {};
    for k=1: numel(fil)

      fullfile(folderdir,fil{k});
      [fid, msg] = fopen(file, 'r');
 if fid < 0
    error('Cannot open file "%s" because "%s"', file, msg);
 end
      b=textscan(fid,'%f %f %f','delimiter',' ');
      fclose(fid);
      x=b{1};
      y=b{2};
      z=b{3};
      data{k} =dataset(x,y,z);
      temp{k} =data{k}; 
    end

    set{j-2} = temp;
    setname{j-2} = foldername;

end

And there is red line under data{k},temp {k}, set{j-2} and setname{j-2} that saying the variable changes size on every loop iteration (within script). Consider preallocating for speed. May i know how could i solve this problem? Thank you.

[Walter Roberson]

projectdir = 'TrainingData';

files = dir(projectdir);
dirFlags = [files.isdir];
subfolders = files(dirFlags);

%do not assume that . and .. are the first two subfolders.
subfoldernames = {subfolders.name};
mask = ismember(subfoldernames, {'.', '..'});
subfoldernames(mask) = [];
subfoldernames = fullfile(projectdir, subfoldernames);

for j = 1 : length(subfoldernames);

      foldername = subfoldernames{j};
      f = dir( fullfile(foldername, '*.DATA') );

      fil = fullfile(foldername, {f.name});  
      temp = {};
      for k = 1: numel(fil)
        filename = fil{k};
        [fid, msg] = fopen(filename, 'r');
        if fid < 0
          error('Cannot open file "%s" because "%s"', file, msg);
        end
        b = textscan(fid,'%f %f %f','delimiter',' ');
        fclose(fid);
        x=b{1};
        y=b{2};
        z=b{3};
        data{k} = dataset(x,y,z);
        temp{k} = data{k}; 
      end

      set{j} = temp;
      setname{j} = foldername;
  end