'find out which indexes correspond to given image set (train or val)
Parameters:
shuffle : boolean
whether to shuffle the image list
Returns:
entire list of images specified in the setting'

def _load_image_set_index(self, shuffle):

    assert os.path.exists(self.list_file), 'Path    does    not    exists:    {}'.format(self.list_file)
    with open(self.list_file, 'r') as f:
        image_set_index = [x.strip() for x in f.readlines()]
    if shuffle:
        np.random.shuffle(image_set_index)
    return image_set_index
