Read images from local disk using torch7 while those images saved in different subfolders?

Question

I have images which have saved in the desk. The data saved as follow: 4 main folders (1,2,3 and 4) each folder has 26 subfolders ( these subfolders represent the class of images (A, B, C, D, ..,Z)). Each of these subfolder contains more than 500 images. However, I am looking for file or code in torch that can read these images. In MATLAB I could wrote a code but here I find it confuse. Could you please advise me.

Answer 1

What you can do is use Penlight (the library is installed when you install Torch).

Penlight provides pl.dir that makes it easy to scan files in (sub-)folders. For example what you can do is:

local pl = require('pl.import_into')()
local t = {}
for i,f in ipairs(pl.dir.getallfiles('/data/foo', '*.jpg')) do
    t[i] = { f, pl.path.basename(pl.path.dirname(f)) }
end

This creates a list of pairs (filename, class label = "A" or "B" ...). Of course you are free to change the file pattern (*.jpg) or to omit it (in such a case Penlight will simply list all files). You can also load the images on the fly:

t[i] = { image.load(f), pl.path.basename(pl.path.dirname(f)) }

Or do that right after when manipulating t.