random extraction of files from a folder

I have a folder of 12000 images (in bmp format). I would like to randomly extract 2000 images and store it in a different folder. How can i do that?

Answer 1

[Jan]

Based on Adam's suggestions:

Dest     = 'C:\Temp';
FileList = dir(fullfile(Folder, '*.bmp'));
Index    = randperm(numel(FileList), 2000);
for k = 1:2000
  Source = fullfile(Folder, FileList(index(k)).name);
  copyfile(Source, Dest);
end

Or movefile.

[Sivaramakrishnan Rajaraman]

Many thanks. It perfectly works..

Answer 2

[Adam]

doc dir

can be used to give you a listing.

doc randperm

can be applied to your listing to select the random files. I don't have time (or inclination) to write the code for you though so feel free to ask further questions once you have made an attempt if you get stuck.

[Sivaramakrishnan Rajaraman]

i wrote the following and it is giving error. Kindly help rectify the code:

myFolder1 = 'Q:\chromosomal Data\Data\16'; %containing 12000 fles
filePattern1 = fullfile(myFolder1, '*.bmp'); 
theFiles1 = dir(filePattern1); % getting a 208x1 struct with 6 fields, containing name, folder, date, bytes, isdir,and datenum
whos theFiles1  % No semicolon!
numFiles1 = length(theFiles1)  % No semicolon!
if numFiles1 == 0 || isempty(theFiles1)
    warningMessage = 'No files found';
    uiwait(warndlg(warningMessage));
    return;
end
p = randperm(theFiles1(2000)); %error index exceeds matrix dimensions

Kindly help to move the random 2000 files to a different folder. name it anything you like.

Answer 3

[ES]

You can do a dir in that folder for a list of files. Use a random number generator of 2000 length.

Select the file based on the random number.