Moving specific files to specific folders

I can create new subfolders based on the first 3 letters of specific filenames with the script below.

cd '/Users/e_isbell/Documents/4y_GNG';

files = dir('*.set');

for i=1:length(files)

    filename = files(i).name;

     folder = filename(1:3);

    mkdir('/Users/e_isbell/Documents/4y_GNG',folder);
end

However, I can't figure out how to move several files that start with those first 3 letters to the matching subfolders.

For instance, I have several files that has '150' for the first 3 letters (the following letters are different for each file). I want to create a subfolder that has these first 3 letters in its name (e.g. '150'), which I can do with the script above. Then I want to move all the files that start with '150' into the subfolder named '150'; all files that start with '155' into the subfolder named '155' and so on, looping through the folder.

Answer 1

[Thorsten]

direc = dir; filenames = {};
[filenames{1:length(direc),1}] = deal(direc.name);

first3 = cellfun(@(x) x(1:3), filenames, 'Uni', 0);
mypath = '/Users/e_isbell/Documents/4y_GNG';

for f3 = unique(first3) 
   mydir = fullfile(mypath, f3);
   mkdir(mydir)
   movefile([f3 '*'], mydir)
end

Answer 2

[elisbe]

Thanks for the promptly reply. This is the error I get:

Error using cellfun Input #2 expected to be a cell array, was struct instead.

[Thorsten]

Uups, I thought that 'files' are the filenames. I've updated my response.