How can I get a list of all directory names and/or all files in a specific directory in MATLAB?

Question

There are two things I want to do:

1. Get a list of all the directory names within a directory, and
2. Get a list of all the file names within a directory

How can I do this in MATLAB?

Right now, I'm trying:

dirnames = dir(image_dir);

but that returns a list of objects, I think. size(dirnames) returns the number of attributes, and dirnames.name only returns the name of the first directory.

Answer 1

The function DIR actually returns a structure array with one structure element per file or subdirectory in the given directory. When getting data from a structure array, accessing a field with dot notation will return a comma-separated list of field values with one value per structure element. This comma-separated list can be collected into a vector by placing it in square brackets [] or a cell array by placing it in curly braces {}.

I usually like to get a list of file or subdirectory names in a directory by making use of logical indexing, like so:

dirInfo = dir(image_dir);            %# Get structure of directory information
isDir = [dirInfo.isdir];             %# A logical index the length of the 
                                     %#   structure array that is true for
                                     %#   structure elements that are
                                     %#   directories and false otherwise
dirNames = {dirInfo(isDir).name};    %# A cell array of directory names
fileNames = {dirInfo(~isDir).name};  %# A cell array of file names

Answer 2

No. you are incorrect about what dirnames.name returns.

D = dir;

This is a structure array. If you want a list of which are directories, do this

isdirlist = find(vertcat(D.isdir));

Or I could have used cell2mat here. Note that if you just try D.name, is returns a comma separated list. You can get all of the names as a cell array simply though.

nameslist = {D.name};

Answer 3

Assuming that "image_dir" is the name of a directory, the following code shows you how to determine which items are directories and which are files and how to get their names. Once you've gotten that far, building a list of only directories or only files is straightforward.

dirnames = dir(image_dir);
for(i = 1:length(dirnames))
   if(dirnames(i).isdir == true)
      % It's a subdirectory
      % The name of the subdirectory can be accessed as dirnames(i).name
      % Note that both '.' and '..' are subdirectories of any directory and
      % should be ignored
   else
      % It's a filename
      % The filename is dirnames(i).name
   end
end