Add load_metadata

lerobot/common/datasets/utils.py

@@ -15,16 +15,16 @@
 # limitations under the License.
 import json
 import warnings
-from functools import cache
 from itertools import accumulate
 from pathlib import Path
 from pprint import pformat
 from typing import Dict
 
 import datasets
+import jsonlines
 import torch
 from datasets import load_dataset
-from huggingface_hub import DatasetCard, HfApi, hf_hub_download
+from huggingface_hub import DatasetCard, HfApi
 from PIL import Image as PILImage
 from torchvision import transforms
 
@@ -96,7 +96,6 @@ def hf_transform_to_torch(items_dict: dict[torch.Tensor | None]):
     return items_dict
 
 
-@cache
 def get_hub_safe_version(repo_id: str, version: str, enforce_v2: bool = True) -> str:
     num_version = float(version.strip("v"))
     if num_version < 2 and enforce_v2:
@@ -144,50 +143,30 @@ def load_hf_dataset(
     return hf_dataset
 
 
-def load_stats(repo_id: str, version: str, local_dir: Path) -> dict[str, dict[str, torch.Tensor]]:
-    """stats contains the statistics per modality computed over the full dataset, such as max, min, mean, std
+def load_metadata(local_dir: Path) -> tuple[dict | list]:
+    """Loads metadata files from a dataset."""
+    info_path = local_dir / "meta/info.json"
+    episodes_path = local_dir / "meta/episodes.jsonl"
+    stats_path = local_dir / "meta/stats.json"
+    tasks_path = local_dir / "meta/tasks.json"
 
-    Example:
-    ```python
-    normalized_action = (action - stats["action"]["mean"]) / stats["action"]["std"]
-    ```
-    """
-    fpath = hf_hub_download(
-        repo_id, filename="meta/stats.json", local_dir=local_dir, repo_type="dataset", revision=version
-    )
-    with open(fpath) as f:
+    with open(info_path) as f:
+        info = json.load(f)
+
+    with jsonlines.open(episodes_path, "r") as reader:
+        episode_dicts = list(reader)
+
+    with open(stats_path) as f:
         stats = json.load(f)
 
-    stats = flatten_dict(stats)
-    stats = {key: torch.tensor(value) for key, value in stats.items()}
-    return unflatten_dict(stats)
-
-
-def load_info(repo_id: str, version: str, local_dir: Path) -> dict:
-    """info contains structural information about the dataset. It should be the reference and
-    act as the 'source of thruth' for what's inside the dataset.
-
-    Example:
-    ```python
-    print("frame per second used to collect the video", info["fps"])
-    ```
-    """
-    fpath = hf_hub_download(
-        repo_id, filename="meta/info.json", local_dir=local_dir, repo_type="dataset", revision=version
-    )
-    with open(fpath) as f:
-        return json.load(f)
-
-
-def load_tasks(repo_id: str, version: str, local_dir: Path) -> dict:
-    """tasks contains all the tasks of the dataset, indexed by their task_index."""
-    fpath = hf_hub_download(
-        repo_id, filename="meta/tasks.json", local_dir=local_dir, repo_type="dataset", revision=version
-    )
-    with open(fpath) as f:
+    with open(tasks_path) as f:
         tasks = json.load(f)
 
-    return {item["task_index"]: item["task"] for item in sorted(tasks, key=lambda x: x["task_index"])}
+    stats = {key: torch.tensor(value) for key, value in flatten_dict(stats).items()}
+    stats = unflatten_dict(stats)
+    tasks = {item["task_index"]: item["task"] for item in sorted(tasks, key=lambda x: x["task_index"])}
+
+    return info, episode_dicts, stats, tasks
 
 
 def get_episode_data_index(episodes: list, episode_dicts: list[dict]) -> dict[str, torch.Tensor]: