fix image path

sun397.py

@@ -549,6 +549,6 @@ class Sun397Dataset(datasets.GeneratorBasedBuilder):
     def _generate_examples(self, images_dir, subset_images):
         for image_name in subset_images:
             label = "/".join(image_name.split("/")[2:-1])
-            image_path = images_dir / image_name
+            image_path = os.path.join(str(images_dir), *image_name.split("/"))
             record = {"image": str(image_path), "label": label}
             yield image_name, record