fix category file generation (#5188)

Author: pmeier

torchvision/prototype/datasets/_builtin/dtd.py

@@ -132,6 +132,9 @@ def _filter_images(self, data: Tuple[str, Any]) -> bool:
         return self._classify_archive(data) == DTDDemux.IMAGES
 
     def _generate_categories(self, root: pathlib.Path) -> List[str]:
-        dp = self.resources(self.default_config)[0].load(pathlib.Path(root) / self.name)
+        resources = self.resources(self.default_config)
+
+        dp = resources[0].load(root)
         dp = Filter(dp, self._filter_images)
+
         return sorted({pathlib.Path(path).parent.name for path, _ in dp})

torchvision/prototype/datasets/_builtin/oxford_iiit_pet.py

@@ -145,10 +145,13 @@ def _filter_split_and_classification_anns(self, data: Tuple[str, Any]) -> bool:
 
     def _generate_categories(self, root: pathlib.Path) -> List[str]:
         config = self.default_config
-        dp = self.resources(config)[1].load(pathlib.Path(root) / self.name)
+        resources = self.resources(config)
+
+        dp = resources[1].load(root)
         dp = Filter(dp, self._filter_split_and_classification_anns)
         dp = Filter(dp, path_comparator("name", f"{config.split}.txt"))
         dp = CSVDictParser(dp, fieldnames=("image_id", "label"), delimiter=" ")
+
         raw_categories_and_labels = {(data["image_id"].rsplit("_", 1)[0], data["label"]) for data in dp}
         raw_categories, _ = zip(
             *sorted(raw_categories_and_labels, key=lambda raw_category_and_label: int(raw_category_and_label[1]))