Add COCO export script

tools/export_coco.py

@@ -0,0 +1,81 @@
+import argparse
+from pathlib import Path
+import orjson
+from datasets import load_dataset
+
+
+def export_split(ds, out_dir: Path, split_name: str):
+    images_dir = out_dir / split_name / "images"
+    ann_dir = out_dir / split_name / "annotations"
+    images_dir.mkdir(parents=True, exist_ok=True)
+    ann_dir.mkdir(parents=True, exist_ok=True)
+
+    images = []
+    annotations = []
+    categories = None
+    ann_id = 1
+
+    for ex in ds:
+        image_id = int(ex["image_id"])
+        filename = ex["filename"]
+        width = int(ex["width"])
+        height = int(ex["height"])
+
+        # write image bytes
+        (images_dir / filename).write_bytes(ex["image_bytes"])
+
+        images.append({
+            "id": image_id,
+            "file_name": filename,
+            "width": width,
+            "height": height,
+        })
+
+        annos = orjson.loads(ex["coco_annotations"].encode("utf-8"))
+        if categories is None:
+            categories = orjson.loads(ex["coco_categories"].encode("utf-8"))
+
+        for a in annos:
+            a = dict(a)
+            a["id"] = ann_id
+            ann_id += 1
+            annotations.append(a)
+
+    coco = {
+        "images": images,
+        "annotations": annotations,
+        "categories": categories or [],
+    }
+    (ann_dir / f"instances_{split_name}.json").write_bytes(orjson.dumps(coco))
+    return len(images), len(annotations)
+
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--repo", required=True, help="HF dataset repo id, e.g. aadityabuilds/tree-distribution-shift")
+    ap.add_argument("--config", required=True, help="config_name")
+    ap.add_argument("--out", required=True, help="output directory")
+    args = ap.parse_args()
+
+    out_dir = Path(args.out) / args.config
+    out_dir.mkdir(parents=True, exist_ok=True)
+
+    # streaming=False ensures export writes locally
+    train = load_dataset(args.repo, args.config, split="train", streaming=False)
+    idt   = load_dataset(args.repo, args.config, split="id_test", streaming=False)
+    ood   = load_dataset(args.repo, args.config, split="ood_test", streaming=False)
+
+    n_i, n_a = export_split(train, out_dir, "train")
+    print(f"[train] images={n_i} annotations={n_a}")
+
+    n_i, n_a = export_split(idt, out_dir, "id_test")
+    print(f"[id_test] images={n_i} annotations={n_a}")
+
+    n_i, n_a = export_split(ood, out_dir, "ood_test")
+    print(f"[ood_test] images={n_i} annotations={n_a}")
+
+    print(f"COCO export written to: {out_dir}")
+
+
+if __name__ == "__main__":
+    main()