Update dataset.py

dataset.py

@@ -13,60 +13,65 @@ class LineGraphicsDataset(GeneratorBasedBuilder):
                 "height": Value("int32"),
                 "instances": Sequence({
                     "category_id": Value("int32"),
-                    "mask": Sequence(Sequence(Value("float32")))  # list of polygon(s)
+                    "mask": Sequence(Sequence(Value("float32")))  # List of polygons (each polygon = list of floats)
                 })
             }),
             description="Line Graphics Dataset with polygon instance masks in COCO format.",
         )
 
     def _split_generators(self, dl_manager):
-        # Automatically download and extract the repo contents
         data_dir = dl_manager.download_and_extract(self.config.data_dir or ".")
 
         return [
             SplitGenerator(
                 name=Split.TRAIN,
-                gen_kwargs={"split_dir": os.path.join(data_dir, "train")}
+                gen_kwargs={"split_dir": os.path.join(data_dir, "train")},
             ),
             SplitGenerator(
                 name=Split.VALIDATION,
-                gen_kwargs={"split_dir": os.path.join(data_dir, "val")}
+                gen_kwargs={"split_dir": os.path.join(data_dir, "val")},
             ),
             SplitGenerator(
                 name=Split.TEST,
-                gen_kwargs={"split_dir": os.path.join(data_dir, "test")}
+                gen_kwargs={"split_dir": os.path.join(data_dir, "test")},
             ),
         ]
 
     def _generate_examples(self, split_dir):
-        # Load annotations.json
-        ann_path = os.path.join(split_dir, "annotations.json")
-        with open(ann_path, "r") as f:
+        # Load annotations
+        annotation_file = os.path.join(split_dir, "annotations.json")
+        with open(annotation_file, "r") as f:
             coco = json.load(f)
 
+        # Map image_id to metadata
         image_id_to_info = {img["id"]: img for img in coco["images"]}
 
+        # Group annotations by image
         from collections import defaultdict
         anns_by_image = defaultdict(list)
         for ann in coco["annotations"]:
             anns_by_image[ann["image_id"]].append(ann)
 
-        for img_id, info in image_id_to_info.items():
-            image_path = os.path.join(split_dir, "images", info["file_name"])
-            width = info["width"]
-            height = info["height"]
+        # Generate examples
+        for image_id, image_info in image_id_to_info.items():
+            file_name = image_info["file_name"]
+            image_path = os.path.join(split_dir, "images", file_name)
 
             instances = []
-            for ann in anns_by_image[img_id]:
+            for ann in anns_by_image[image_id]:
+                # Each mask is a list of polygons
+                segmentation = ann["segmentation"]
+                if not isinstance(segmentation, list):
+                    continue  # skip if malformed
                 instances.append({
                     "category_id": ann["category_id"],
-                    "mask": ann["segmentation"]  # List of polygons
+                    "mask": segmentation
                 })
 
-            yield info["file_name"], {
-                "image_name": info["file_name"],
+            yield file_name, {
+                "image_name": file_name,
                 "image": image_path,
-                "width": width,
-                "height": height,
+                "width": image_info["width"],
+                "height": image_info["height"],
                 "instances": instances
             }