remove bad typing

src/lerobot/datasets/aggregate.py

@@ -15,10 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import contextlib
 import logging
 import shutil
-from concurrent.futures import ThreadPoolExecutor, as_completed
 from pathlib import Path
 
 import pandas as pd
@@ -109,7 +107,6 @@ def update_meta_data(
     dst_meta,
     meta_idx,
     data_idx,
-    data_file_map,
     videos_idx,
 ):
     """Updates metadata DataFrame with new chunk, file, and timestamp indices.
@@ -130,25 +127,8 @@ def update_meta_data(
 
     df["meta/episodes/chunk_index"] = df["meta/episodes/chunk_index"] + meta_idx["chunk"]
     df["meta/episodes/file_index"] = df["meta/episodes/file_index"] + meta_idx["file"]
-    # Remap data chunk/file indices per-source-file using the actual destination
-    # file chosen during data aggregation. A flat offset is incorrect when
-    # multiple source files are concatenated into a single destination file.
-    if data_file_map:
-        new_data_chunk = []
-        new_data_file = []
-        for idx in df.index:
-            src_chunk = int(df.at[idx, "data/chunk_index"])  # original source file location
-            src_file = int(df.at[idx, "data/file_index"])  # original source file location
-            dst_chunk, dst_file = data_file_map.get(
-                (src_chunk, src_file), (src_chunk + data_idx["chunk"], src_file + data_idx["file"])
-            )
-            new_data_chunk.append(dst_chunk)
-            new_data_file.append(dst_file)
-        df["data/chunk_index"] = new_data_chunk
-        df["data/file_index"] = new_data_file
-    else:
-        df["data/chunk_index"] = df["data/chunk_index"] + data_idx["chunk"]
-        df["data/file_index"] = df["data/file_index"] + data_idx["file"]
+    df["data/chunk_index"] = df["data/chunk_index"] + data_idx["chunk"]
+    df["data/file_index"] = df["data/file_index"] + data_idx["file"]
     for key, video_idx in videos_idx.items():
         # Store original video file indices before updating
         orig_chunk_col = f"videos/{key}/chunk_index"
@@ -186,7 +166,7 @@ def update_meta_data(
     return df
 
 
-def _aggregate_datasets(
+def aggregate_datasets(
     repo_ids: list[str],
     aggr_repo_id: str,
     roots: list[Path] | None = None,
@@ -195,24 +175,39 @@ def _aggregate_datasets(
     video_files_size_in_mb: float | None = None,
     chunk_size: int | None = None,
 ):
-    """Serial aggregation kernel: combines datasets into a destination dataset.
+    """Aggregates multiple LeRobot datasets into a single unified dataset.
 
-    This function performs a single-process aggregation. It assumes it is the
-    sole writer for its destination `aggr_root`.
+    This is the main function that orchestrates the aggregation process by:
+    1. Loading and validating all source dataset metadata
+    2. Creating a new destination dataset with unified tasks
+    3. Aggregating videos, data, and metadata from all source datasets
+    4. Finalizing the aggregated dataset with proper statistics
+
+    Args:
+        repo_ids: List of repository IDs for the datasets to aggregate.
+        aggr_repo_id: Repository ID for the aggregated output dataset.
+        roots: Optional list of root paths for the source datasets.
+        aggr_root: Optional root path for the aggregated dataset.
+        data_files_size_in_mb: Maximum size for data files in MB (defaults to DEFAULT_DATA_FILE_SIZE_IN_MB)
+        video_files_size_in_mb: Maximum size for video files in MB (defaults to DEFAULT_VIDEO_FILE_SIZE_IN_MB)
+        chunk_size: Maximum number of files per chunk (defaults to DEFAULT_CHUNK_SIZE)
     """
-    # Build metadata objects, supporting a per-dataset "root" that may be None.
-    # When root is provided we load from the local filesystem, otherwise from Hub cache.
-    if roots is None:
-        all_metadata = [LeRobotDatasetMetadata(repo_id) for repo_id in repo_ids]
-    else:
-        all_metadata = [
-            (
-                LeRobotDatasetMetadata(repo_id, root=root)
-                if root is not None
-                else LeRobotDatasetMetadata(repo_id)
-            )
-            for repo_id, root in zip(repo_ids, roots, strict=False)
+    logging.info("Start aggregate_datasets")
+
+    if data_files_size_in_mb is None:
+        data_files_size_in_mb = DEFAULT_DATA_FILE_SIZE_IN_MB
+    if video_files_size_in_mb is None:
+        video_files_size_in_mb = DEFAULT_VIDEO_FILE_SIZE_IN_MB
+    if chunk_size is None:
+        chunk_size = DEFAULT_CHUNK_SIZE
+
+    all_metadata = (
+        [LeRobotDatasetMetadata(repo_id) for repo_id in repo_ids]
+        if roots is None
+        else [
+            LeRobotDatasetMetadata(repo_id, root=root) for repo_id, root in zip(repo_ids, roots, strict=False)
         ]
+    )
     fps, robot_type, features = validate_all_metadata(all_metadata)
     video_keys = [key for key in features if features[key]["dtype"] == "video"]
 
@@ -242,11 +237,9 @@ def _aggregate_datasets(
 
     for src_meta in tqdm.tqdm(all_metadata, desc="Copy data and videos"):
         videos_idx = aggregate_videos(src_meta, dst_meta, videos_idx, video_files_size_in_mb, chunk_size)
-        data_idx, data_file_map = aggregate_data(
-            src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_size
-        )
+        data_idx = aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_size)
 
-        meta_idx = aggregate_metadata(src_meta, dst_meta, meta_idx, data_idx, data_file_map, videos_idx)
+        meta_idx = aggregate_metadata(src_meta, dst_meta, meta_idx, data_idx, videos_idx)
 
         dst_meta.info["total_episodes"] += src_meta.total_episodes
         dst_meta.info["total_frames"] += src_meta.total_frames
@@ -255,168 +248,6 @@ def _aggregate_datasets(
     logging.info("Aggregation complete.")
 
 
-def aggregate_datasets(
-    repo_ids: list[str],
-    aggr_repo_id: str,
-    roots: list[Path] | None = None,
-    aggr_root: Path | None = None,
-    data_files_size_in_mb: float | None = None,
-    video_files_size_in_mb: float | None = None,
-    chunk_size: int | None = None,
-    num_workers: int | None = None,
-    tmp_root: Path | None = None,
-):
-    """Aggregates multiple LeRobot datasets into a single unified dataset.
-
-    This is the main function that orchestrates the aggregation process by:
-    1. Loading and validating all source dataset metadata
-    2. Creating a new destination dataset with unified tasks
-    3. Aggregating videos, data, and metadata from all source datasets
-    4. Finalizing the aggregated dataset with proper statistics
-
-    Args:
-        repo_ids: List of repository IDs for the datasets to aggregate.
-        aggr_repo_id: Repository ID for the aggregated output dataset.
-        roots: Optional list of root paths for the source datasets.
-        aggr_root: Optional root path for the aggregated dataset.
-        data_files_size_in_mb: Maximum size for data files in MB (defaults to DEFAULT_DATA_FILE_SIZE_IN_MB)
-        video_files_size_in_mb: Maximum size for video files in MB (defaults to DEFAULT_VIDEO_FILE_SIZE_IN_MB)
-        chunk_size: Maximum number of files per chunk (defaults to DEFAULT_CHUNK_SIZE)
-        num_workers: When > 1, performs a tree-based parallel reduction using a thread pool
-        tmp_root: Optional base directory to store intermediate reduction outputs
-    """
-    logging.info("Start aggregate_datasets")
-
-    if data_files_size_in_mb is None:
-        data_files_size_in_mb = DEFAULT_DATA_FILE_SIZE_IN_MB
-    if video_files_size_in_mb is None:
-        video_files_size_in_mb = DEFAULT_VIDEO_FILE_SIZE_IN_MB
-    if chunk_size is None:
-        chunk_size = DEFAULT_CHUNK_SIZE
-
-    if num_workers is None or num_workers <= 1:
-        # Run aggregation sequentially
-        _aggregate_datasets(
-            repo_ids=repo_ids,
-            aggr_repo_id=aggr_repo_id,
-            aggr_root=aggr_root,
-            roots=roots,
-            data_files_size_in_mb=data_files_size_in_mb,
-            video_files_size_in_mb=video_files_size_in_mb,
-            chunk_size=chunk_size,
-        )
-
-    # Uses a parallel fan-out/fan-in strategy when num_workers is provided
-    elif num_workers > 1:
-        # Validate across all metadata early to fail fast
-        all_metadata_for_validation = (
-            [LeRobotDatasetMetadata(repo_id) for repo_id in repo_ids]
-            if roots is None
-            else [
-                LeRobotDatasetMetadata(repo_id, root=root)
-                for repo_id, root in zip(repo_ids, roots, strict=False)
-            ]
-        )
-        validate_all_metadata(all_metadata_for_validation)
-
-        # Clamp workers to a sensible upper bound (pairs per round)
-        num_workers = min(num_workers, max(1, len(repo_ids) // 2))
-
-        # Choose a base temporary root for intermediate merge results
-        if tmp_root is not None:
-            base_tmp_root = tmp_root
-        elif aggr_root is not None:
-            base_tmp_root = aggr_root.parent / f".{aggr_repo_id}__tmp"
-        else:
-            base_tmp_root = Path.cwd() / f".{aggr_repo_id}__tmp"
-        base_tmp_root.mkdir(parents=True, exist_ok=True)
-
-        current_repo_ids: list[str] = list(repo_ids)
-        # Always maintain a roots list aligned with repo_ids. Use None for Hub-backed inputs.
-        current_roots: list[Path | None] = list(roots) if roots is not None else [None] * len(repo_ids)
-
-        try:
-            level = 0
-            while len(current_repo_ids) > 1:
-                next_repo_ids: list[str] = []
-                next_roots: list[Path | None] = []
-                futures = []
-
-                with ThreadPoolExecutor(max_workers=num_workers) as executor:
-                    group_index = 0
-                    i = 0
-                    while i < len(current_repo_ids):
-                        group_repo_ids = current_repo_ids[i : i + 2]
-                        group_roots = current_roots[i : i + 2]
-
-                        if len(group_repo_ids) == 1:
-                            # Carry over singleton to next level
-                            next_repo_ids.append(group_repo_ids[0])
-                            next_roots.append(group_roots[0])
-                            i += 1
-                            continue
-
-                        out_repo_id = f"{aggr_repo_id}__reduce_l{level}_g{group_index}"
-                        out_root = base_tmp_root / f"reduce_l{level}_g{group_index}"
-
-                        futures.append(
-                            executor.submit(
-                                _aggregate_datasets,
-                                group_repo_ids,
-                                out_repo_id,
-                                group_roots,
-                                out_root,
-                                data_files_size_in_mb,
-                                video_files_size_in_mb,
-                                chunk_size,
-                            )
-                        )
-
-                        next_repo_ids.append(out_repo_id)
-                        next_roots.append(out_root)
-
-                        i += 2
-                        group_index += 1
-
-                    for f in as_completed(futures):
-                        # Bubble up any exception raised inside tasks
-                        f.result()
-
-                # Cleanup previous level temporary outputs that won't be used again
-                base_resolved = base_tmp_root.resolve()
-                keep_set = {nr.resolve() for nr in next_roots if nr is not None}
-                for prev_root in current_roots:
-                    if prev_root is None:
-                        continue
-                    # Suppress per-iteration to keep cleaning other roots even if one fails
-                    with contextlib.suppress(Exception):
-                        pr = prev_root.resolve()
-                        if pr not in keep_set and base_resolved in pr.parents:
-                            shutil.rmtree(prev_root, ignore_errors=True)
-
-                current_repo_ids = next_repo_ids
-                current_roots = next_roots  # aligned list of Path|None after first level
-                level += 1
-
-            # Final copy/aggregation into the desired output
-            _aggregate_datasets(
-                repo_ids=current_repo_ids,
-                aggr_repo_id=aggr_repo_id,
-                roots=current_roots,
-                aggr_root=aggr_root,
-                data_files_size_in_mb=data_files_size_in_mb,
-                video_files_size_in_mb=video_files_size_in_mb,
-                chunk_size=chunk_size,
-            )
-        finally:
-            # Remove all temporary reduction artifacts
-            with contextlib.suppress(Exception):
-                shutil.rmtree(base_tmp_root, ignore_errors=True)
-
-        logging.info("Aggregation complete.")
-        return
-
-
 def aggregate_videos(src_meta, dst_meta, videos_idx, video_files_size_in_mb, chunk_size):
     """Aggregates video chunks from a source dataset into the destination dataset.
 
@@ -535,9 +366,6 @@ def aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_si
 
     unique_chunk_file_ids = sorted(unique_chunk_file_ids)
 
-    # Map source (chunk,file) -> destination (chunk,file) actually used during write
-    src_to_dst_file: dict[tuple[int, int], tuple[int, int]] = {}
-
     for src_chunk_idx, src_file_idx in unique_chunk_file_ids:
         src_path = src_meta.root / DEFAULT_DATA_PATH.format(
             chunk_index=src_chunk_idx, file_index=src_file_idx
@@ -545,7 +373,7 @@ def aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_si
         df = pd.read_parquet(src_path)
         df = update_data_df(df, src_meta, dst_meta)
 
-        data_idx, used_chunk, used_file = append_or_create_parquet_file(
+        data_idx = append_or_create_parquet_file(
             df,
             src_path,
             data_idx,
@@ -555,12 +383,11 @@ def aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_si
             contains_images=len(dst_meta.image_keys) > 0,
             aggr_root=dst_meta.root,
         )
-        src_to_dst_file[(src_chunk_idx, src_file_idx)] = (used_chunk, used_file)
 
-    return data_idx, src_to_dst_file
+    return data_idx
 
 
-def aggregate_metadata(src_meta, dst_meta, meta_idx, data_idx, data_file_map, videos_idx):
+def aggregate_metadata(src_meta, dst_meta, meta_idx, data_idx, videos_idx):
     """Aggregates metadata from a source dataset into the destination dataset.
 
     Reads source metadata files, updates all indices and timestamps,
@@ -594,11 +421,10 @@ def aggregate_metadata(src_meta, dst_meta, meta_idx, data_idx, data_file_map, vi
             dst_meta,
             meta_idx,
             data_idx,
-            data_file_map,
             videos_idx,
         )
 
-        meta_idx, _m_used_chunk, _m_used_file = append_or_create_parquet_file(
+        meta_idx = append_or_create_parquet_file(
             df,
             src_path,
             meta_idx,
@@ -652,7 +478,7 @@ def append_or_create_parquet_file(
             to_parquet_with_hf_images(df, dst_path)
         else:
             df.to_parquet(dst_path)
-        return idx, idx["chunk"], idx["file"]
+        return idx
 
     src_size = get_parquet_file_size_in_mb(src_path)
     dst_size = get_parquet_file_size_in_mb(dst_path)
@@ -663,19 +489,17 @@ def append_or_create_parquet_file(
         new_path.parent.mkdir(parents=True, exist_ok=True)
         final_df = df
         target_path = new_path
-        used_chunk, used_file = idx["chunk"], idx["file"]
     else:
         existing_df = pd.read_parquet(dst_path)
         final_df = pd.concat([existing_df, df], ignore_index=True)
         target_path = dst_path
-        used_chunk, used_file = idx["chunk"], idx["file"]
 
     if contains_images:
         to_parquet_with_hf_images(final_df, target_path)
     else:
         final_df.to_parquet(target_path)
 
-    return idx, used_chunk, used_file
+    return idx
 
 
 def finalize_aggregation(aggr_meta, all_metadata):

src/lerobot/datasets/dataset_tools.py

@@ -234,7 +234,6 @@ def merge_datasets(
     datasets: list[LeRobotDataset],
     output_repo_id: str,
     output_dir: str | Path | None = None,
-    num_workers: int | None = None,
 ) -> LeRobotDataset:
     """Merge multiple LeRobotDatasets into a single dataset.
 
@@ -258,7 +257,6 @@ def merge_datasets(
         aggr_repo_id=output_repo_id,
         roots=roots,
         aggr_root=output_dir,
-        num_workers=num_workers,
     )
 
     merged_dataset = LeRobotDataset(
@@ -331,7 +329,7 @@ def modify_features(
 
     if repo_id is None:
         repo_id = f"{dataset.repo_id}_modified"
-    output_dir = Path(output_dir, exists_ok=True) if output_dir is not None else HF_LEROBOT_HOME / repo_id
+    output_dir = Path(output_dir) if output_dir is not None else HF_LEROBOT_HOME / repo_id
 
     new_features = dataset.meta.features.copy()
 

src/lerobot/datasets/lerobot_dataset.py

@@ -940,26 +940,11 @@ class LeRobotDataset(torch.utils.data.Dataset):
         return query_timestamps
 
     def _query_hf_dataset(self, query_indices: dict[str, list[int]]) -> dict:
-        """
-        Query dataset for indices across keys, skipping video keys.
-
-        Tries column-first [key][indices] for speed, falls back to row-first.
-
-        Args:
-            query_indices: Dict mapping keys to index lists to retrieve
-
-        Returns:
-            Dict with stacked tensors of queried data (video keys excluded)
-        """
-        result: dict = {}
-        for key, q_idx in query_indices.items():
-            if key in self.meta.video_keys:
-                continue
-            try:
-                result[key] = torch.stack(self.hf_dataset[key][q_idx])
-            except (KeyError, TypeError, IndexError):
-                result[key] = torch.stack(self.hf_dataset[q_idx][key])
-        return result
+        return {
+            key: torch.stack(self.hf_dataset[q_idx][key])
+            for key, q_idx in query_indices.items()
+            if key not in self.meta.video_keys
+        }
 
     def _query_videos(self, query_timestamps: dict[str, list[float]], ep_idx: int) -> dict[str, torch.Tensor]:
         """Note: When using data workers (e.g. DataLoader with num_workers>0), do not call this function

src/lerobot/datasets/v30/convert_dataset_v21_to_v30.py

@@ -50,9 +50,9 @@ from typing import Any
 
 import jsonlines
 import pandas as pd
-import pyarrow as pa
+import pyarrow.parquet as pq
 import tqdm
-from datasets import Dataset, Features, Image
+from datasets import Dataset, concatenate_datasets
 from huggingface_hub import HfApi, snapshot_download
 from requests import HTTPError
 
@@ -68,6 +68,7 @@ from lerobot.datasets.utils import (
     LEGACY_EPISODES_STATS_PATH,
     LEGACY_TASKS_PATH,
     cast_stats_to_numpy,
+    embed_images,
     flatten_dict,
     get_file_size_in_mb,
     get_parquet_file_size_in_mb,
@@ -174,25 +175,33 @@ def convert_tasks(root, new_root):
     write_tasks(df_tasks, new_root)
 
 
-def concat_data_files(paths_to_cat, new_root, chunk_idx, file_idx, image_keys):
-    # TODO(rcadene): to save RAM use Dataset.from_parquet(file) and concatenate_datasets
-    dataframes = [pd.read_parquet(file) for file in paths_to_cat]
-    # Concatenate all DataFrames along rows
-    concatenated_df = pd.concat(dataframes, ignore_index=True)
+def concat_data_files(
+    paths_to_cat: list[Path], new_root: Path, chunk_idx: int, file_idx: int, image_keys: list[str]
+):
+    """Concatenate multiple parquet data files into a single file.
+
+    Args:
+        paths_to_cat: List of parquet file paths to concatenate
+        new_root: Root directory for the new dataset
+        chunk_idx: Chunk index for the output file
+        file_idx: File index within the chunk
+        image_keys: List of feature keys that contain images
+    """
+
+    datasets_list: list[Dataset] = [Dataset.from_parquet(str(file)) for file in paths_to_cat]
+    concatenated_ds: Dataset = concatenate_datasets(datasets_list)
+
+    if len(image_keys) > 0:
+        logging.debug(f"Embedding {len(image_keys)} image features for optimal training performance")
+        concatenated_ds = embed_images(concatenated_ds)
 
     path = new_root / DEFAULT_DATA_PATH.format(chunk_index=chunk_idx, file_index=file_idx)
     path.parent.mkdir(parents=True, exist_ok=True)
 
-    if len(image_keys) > 0:
-        schema = pa.Schema.from_pandas(concatenated_df)
-        features = Features.from_arrow_schema(schema)
-        for key in image_keys:
-            features[key] = Image()
-        schema = features.arrow_schema
-    else:
-        schema = None
-
-    concatenated_df.to_parquet(path, index=False, schema=schema)
+    table = concatenated_ds.with_format("arrow")[:]
+    writer = pq.ParquetWriter(path, schema=table.schema, compression="snappy", use_dictionary=True)
+    writer.write_table(table)
+    writer.close()
 
 
 def convert_data(root: Path, new_root: Path, data_file_size_in_mb: int):

src/lerobot/scripts/lerobot_edit_dataset.py

@@ -103,7 +103,6 @@ class SplitConfig:
 class MergeConfig:
     type: str = "merge"
     repo_ids: list[str] | None = None
-    num_workers: int | None = None
 
 
 @dataclass
@@ -216,7 +215,6 @@ def handle_merge(cfg: EditDatasetConfig) -> None:
         datasets,
         output_repo_id=cfg.repo_id,
         output_dir=output_dir,
-        num_workers=cfg.operation.num_workers,
     )
 
     logging.info(f"Merged dataset saved to {output_dir}")