[data augmentation] random image flip left/right

def _random_flip_left_right(image_batch, label_batch, batch_size):


    for i in range(batch_size):

        if (np.random.rand(1) < 0.5):
            sign = -1.0
            tmp_image = np.fliplr(image_batch[i, :, :, :])
        else:
            sign = 1.0
            tmp_image = image_batch[i, :, :, :]


        tmp_steer = label_batch[i, 0]

        image_batch[i, :, :, :] = tmp_image
        label_batch[i, 0] = sign * tmp_steer

    return image_batch, label_batch