Split_from_df with ImageImageList.from_folder

I am trying to split a dataset into validation and training set. The dataset is in folders so I have created a function to randomly select some images from each subfolder and that is where I produced a CSV file with all image names in the validation set.

I have tried to use

data = (ImageImageList.from_folder(images)        
              .split_from_df(df['idx'])
       )

And it does not work.
How would you suggest this can be split using the filenames from csv.