- Added missing license in the new scripts

- Added back legacy functions in conversion script of v2 to v21
 - Updated README description for dataset_v3

src/lerobot/datasets/v21/convert_dataset_v20_to_v21.py

@@ -33,16 +33,38 @@ python -m lerobot.datasets.v21.convert_dataset_v20_to_v21 \
 
 import argparse
 import logging
+from pathlib import Path
 
+import jsonlines
 from huggingface_hub import HfApi
 
 from lerobot.datasets.lerobot_dataset import CODEBASE_VERSION, LeRobotDataset
-from lerobot.datasets.utils import LEGACY_EPISODES_STATS_PATH, STATS_PATH, load_stats, write_info
+from lerobot.datasets.utils import STATS_PATH, load_stats, serialize_dict, write_info
 from lerobot.datasets.v21.convert_stats import check_aggregate_stats, convert_stats
 
 V20 = "v2.0"
 V21 = "v2.1"
 
+### LEGACY FUNCTIONS REMOVED FROM UTILS ###
+
+LEGACY_EPISODES_STATS_PATH = "episodes_stats.jsonl"
+
+
+def append_jsonlines(data: dict, fpath: Path) -> None:
+    fpath.parent.mkdir(exist_ok=True, parents=True)
+    with jsonlines.open(fpath, "a") as writer:
+        writer.write(data)
+
+
+def legacy_write_episode_stats(episode_index: int, episode_stats: dict, local_dir: Path):
+    # We wrap episode_stats in a dictionary since `episode_stats["episode_index"]`
+    # is a dictionary of stats and not an integer.
+    episode_stats = {"episode_index": episode_index, "stats": serialize_dict(episode_stats)}
+    append_jsonlines(episode_stats, local_dir / LEGACY_EPISODES_STATS_PATH)
+
+
+######## END OF LEGACY FUNCTIONS ########
+
 
 class SuppressWarnings:
     def __enter__(self):
@@ -61,9 +83,6 @@ def convert_dataset(
     with SuppressWarnings():
         dataset = LeRobotDataset(repo_id, revision=V20, force_cache_sync=True)
 
-    if (dataset.root / LEGACY_EPISODES_STATS_PATH).is_file():
-        (dataset.root / LEGACY_EPISODES_STATS_PATH).unlink()
-
     convert_stats(dataset, num_workers=num_workers)
     ref_stats = load_stats(dataset.root)
     check_aggregate_stats(dataset, ref_stats)

src/lerobot/datasets/v30/convert_dataset_v21_to_v30.py

@@ -1,3 +1,19 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 """
 This script will help you convert any LeRobot dataset already pushed to the hub from codebase version 2.1 to
 3.0. It will:
@@ -11,7 +27,7 @@ This script will help you convert any LeRobot dataset already pushed to the hub
 Usage:
 
 ```bash
-python lerobot/datasets/v30/convert_dataset_v21_to_v30.py \
+python src/lerobot/datasets/v30/convert_dataset_v21_to_v30.py \
     --repo-id=lerobot/pusht
 ```