Selecting n random elements within a for loop

3 views (last 30 days)
Hi everyone,
So assume I have a dataset with 10 folders (each folder corresponding to a category).
In my example :
ListOfAllCategories is a 1x10 cell containing the list of all categories
ImageListForEachCategory is a 10x1 map that returns all images belonging to a given category.
My goal is to (1) "extract" all images belonging to all 10 categories and (2) draw n random images from the whole pool (all categories combined). However, I am encountering problems at the very beginning of the code. I am doing the following (to begin with) :
for i=1:length(ListOfAllCategories)
A = ListOfAllCategories{i};
B = ImageListForEachCategory(A);
disp(B)
end
When I display "B", I get a list of all the images from all categories but the folder in the workspace contains only the images belonging to the first category. Should I use a second For Loop in that case? Also, is there a different way to directly draw n images from the whole pool?
Thank you very much.
Best regards.

Accepted Answer

Image Analyst
Image Analyst on 14 Sep 2020
Have you seen dir() with two **?
% Get a list of all PNG files in all subfolders of topLevelFolder.
allFiles = dir([topLevelFolder, '**/*.png']); % All files in all 10 subfolders.
% Get only a subset of n of them:
randomIndexes = randperm(length(allFiles), n);
subset = allFiles(randomIndexes)
  7 Comments
Image Analyst
Image Analyst on 19 Sep 2020
Yes, you can call my attached function twice to get the grandparent of a folder. If it's the same as the top level folder, it's exactly 2 levels deep.

Sign in to comment.

More Answers (0)

Categories

Find more on File Operations in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!