Create dataset.py

dataset.py

@@ -0,0 +1,72 @@
+import os
+import json
+from datasets import GeneratorBasedBuilder, DatasetInfo, SplitGenerator, Split, Features, Value, Sequence, Image as HFImage
+
+
+class LineGraphicsDataset(GeneratorBasedBuilder):
+    def _info(self):
+        return DatasetInfo(
+            features=Features({
+                "image_name": Value("string"),
+                "image": HFImage(),
+                "width": Value("int32"),
+                "height": Value("int32"),
+                "instances": Sequence({
+                    "category_id": Value("int32"),
+                    "mask": Sequence(Sequence(Value("float32")))  # list of polygon(s)
+                })
+            }),
+            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")}
+            ),
+            SplitGenerator(
+                name=Split.VALIDATION,
+                gen_kwargs={"split_dir": os.path.join(data_dir, "val")}
+            ),
+            SplitGenerator(
+                name=Split.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:
+            coco = json.load(f)
+
+        image_id_to_info = {img["id"]: img for img in coco["images"]}
+
+        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"]
+
+            instances = []
+            for ann in anns_by_image[img_id]:
+                instances.append({
+                    "category_id": ann["category_id"],
+                    "mask": ann["segmentation"]  # List of polygons
+                })
+
+            yield info["file_name"], {
+                "image_name": info["file_name"],
+                "image": image_path,
+                "width": width,
+                "height": height,
+                "instances": instances
+            }