How does the following code works?

r_idx = random('unid', size(listing, 1));
im_input = imread(strcat('D:\project\CVPR17_training_code\data_generation\image\input\', listing(r_idx).name));

I found this code .But ,I couldn't understand how the random() and size() function works.Please explain this...

[Walter Roberson]

You can also use

r_idx = randi(length (listing)) ;

The idea is to choose a random positive integer from 1 to the number of files available, and then use that random integer to select the corresponding file name.

[Dhanubala A]

When i run your code,the following error occurs. "Error using imread (line 349) File "D:\project\CVPR17_training_code\data_generation\image\label\931_4.jpg" does not exist.

Error in generate_train (line 31) im_label = imread(strcat('D:\project\CVPR17_training_code\data_generation\image\label\', listing(r_idx).name)); % label: clean image"

[Walter Roberson]

As an outside person, I have no reason to expect that you have given the correct path to the files.

You should learn how to use fullfile()

projectdir = 'D:\etc'
listing = dir( fullfile(projectdir, '*.jpg'));
ridx = randi(length (listing))
thisfile = fullfile (projectdir, listing(ridx).name));
imread(thisfile)