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* Update docs/source/lerobot-dataset-v3.mdx

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>

* Update docs/source/lerobot-dataset-v3.mdx

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>

* Update docs/source/lerobot-dataset-v3.mdx

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>

---------

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Michel Aractingi <michel.aractingi@huggingface.co>
Co-authored-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>
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2025-09-16 17:45:38 +02:00
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title: Train RL in Simulation
- local: async
title: Use Async Inference
title: "Tutorials"
- sections:
- local: lerobot-dataset-v3
title: Using LeRobotDataset
- local: porting_datasets_v3
title: Porting Large Datasets
title: "Tutorials"
title: "Datasets"
- sections:
- local: smolvla
title: Finetune SmolVLA

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# LeRobotDataset v3.0
`LeRobotDataset v3.0` is a standardized format for robot learning data. It provides unified access to multi-modal time-series data, sensorimotor signals and multicamera video, as well as rich metadata for indexing, search, and visualization on the Hugging Face Hub.
This docs will guide you to:
- Understand the v3.0 design and directory layout
- Record a dataset and push it to the Hub
- Load datasets for training with `LeRobotDataset`
- Stream datasets without downloading using `StreamingLeRobotDataset`
- Migrate existing `v2.1` datasets to `v3.0`
## Whats new in `v3`
- **File-based storage**: Many episodes per Parquet/MP4 file (v2 used one file per episode).
- **Relational metadata**: Episode boundaries and lookups are resolved through metadata, not filenames.
- **Hub-native streaming**: Consume datasets directly from the Hub with `StreamingLeRobotDataset`.
- **Lower file-system pressure**: Fewer, larger files ⇒ faster initialization and fewer issues at scale.
- **Unified organization**: Clean directory layout with consistent path templates across data and videos.
## Installation
`LeRobotDataset v3.0` will be included in `lerobot >= 0.4.0`.
Until that stable release, you can use the main branch by following the [build from source instructions](./installation#from-source).
## Record a dataset
Run the command below to record a dataset with the SO-101 and push to the Hub:
```bash
lerobot-record \
--robot.type=so101_follower \
--robot.port=/dev/tty.usbmodem585A0076841 \
--robot.id=my_awesome_follower_arm \
--robot.cameras="{ front: {type: opencv, index_or_path: 0, width: 1920, height: 1080, fps: 30}}" \
--teleop.type=so101_leader \
--teleop.port=/dev/tty.usbmodem58760431551 \
--teleop.id=my_awesome_leader_arm \
--display_data=true \
--dataset.repo_id=${HF_USER}/record-test \
--dataset.num_episodes=5 \
--dataset.single_task="Grab the black cube"
```
See the [recording guide](./il_robots#record-a-dataset) for more details.
## Format design
A core v3 principle is **decoupling storage from the user API**: data is stored efficiently (few large files), while the public API exposes intuitive episode-level access.
`v3` has three pillars:
1. **Tabular data**: Lowdimensional, highfrequency signals (states, actions, timestamps) stored in **Apache Parquet**. Access is memorymapped or streamed via the `datasets` stack.
2. **Visual data**: Camera frames concatenated and encoded into **MP4**. Frames from the same episode are grouped; videos are sharded per camera for practical sizes.
3. **Metadata**: JSON/Parquet records describing schema (feature names, dtypes, shapes), frame rates, normalization stats, and **episode segmentation** (start/end offsets into shared Parquet/MP4 files).
> To scale to millions of episodes, tabular rows and video frames from multiple episodes are **concatenated** into larger files. Episodespecific views are reconstructed **via metadata**, not file boundaries.
<div style="display:flex; justify-content:center; gap:12px; flex-wrap:wrap;">
<figure style="margin:0; text-align:center;">
<img
src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/lerobotdataset-v3/asset1datasetv3.png"
alt="LeRobotDataset v3 diagram"
width="220"
/>
<figcaption style="font-size:0.9em; color:#666;">
From episodebased to filebased datasets
</figcaption>
</figure>
</div>
### Directory layout (simplified)
- **`meta/info.json`**: canonical schema (features, shapes/dtypes), FPS, codebase version, and **path templates** to locate data/video shards.
- **`meta/stats.json`**: global feature statistics (mean/std/min/max) used for normalization; exposed as `dataset.meta.stats`.
- **`meta/tasks.jsonl`**: naturallanguage task descriptions mapped to integer IDs for taskconditioned policies.
- **`meta/episodes/`**: perepisode records (lengths, tasks, offsets) stored as **chunked Parquet** for scalability.
- **`data/`**: framebyframe **Parquet** shards; each file typically contains **many episodes**.
- **`videos/`**: **MP4** shards per camera; each file typically contains **many episodes**.
## Load a dataset for training
`LeRobotDataset` returns Python dictionaries of PyTorch tensors and integrates with `torch.utils.data.DataLoader`. Here is a code example showing its use:
```python
import torch
from lerobot.datasets.lerobot_dataset import LeRobotDataset
repo_id = "yaak-ai/L2D-v3"
# 1) Load from the Hub (cached locally)
dataset = LeRobotDataset(repo_id)
# 2) Random access by index
sample = dataset[100]
print(sample)
# {
# 'observation.state': tensor([...]),
# 'action': tensor([...]),
# 'observation.images.front_left': tensor([C, H, W]),
# 'timestamp': tensor(1.234),
# ...
# }
# 3) Temporal windows via delta_timestamps (seconds relative to t)
delta_timestamps = {
"observation.images.front_left": [-0.2, -0.1, 0.0] # 0.2s and 0.1s before current frame
}
dataset = LeRobotDataset(repo_id, delta_timestamps=delta_timestamps)
# Accessing an index now returns a stack for the specified key(s)
sample = dataset[100]
print(sample["observation.images.front_left"].shape) # [T, C, H, W], where T=3
# 4) Wrap with a DataLoader for training
batch_size = 16
data_loader = torch.utils.data.DataLoader(dataset, batch_size=batch_size)
device = "cuda" if torch.cuda.is_available() else "cpu"
for batch in data_loader:
observations = batch["observation.state"].to(device)
actions = batch["action"].to(device)
images = batch["observation.images.front_left"].to(device)
# model.forward(batch)
```
## Stream a dataset (no downloads)
Use `StreamingLeRobotDataset` to iterate directly from the Hub without local copies. This allows to stream large datasets without the need to downloading them onto disk or loading them onto memory, and is a key feature of the new dataset format.
```python
from lerobot.datasets.streaming_dataset import StreamingLeRobotDataset
repo_id = "yaak-ai/L2D-v3"
dataset = StreamingLeRobotDataset(repo_id) # streams directly from the Hub
```
<div style="display:flex; justify-content:center; gap:12px; flex-wrap:wrap;">
<figure style="margin:0; text-align:center;">
<img
src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/lerobotdataset-v3/streaming-lerobot.png"
alt="StreamingLeRobotDataset"
width="520"
/>
<figcaption style="font-size:0.9em; color:#666;">
Stream directly from the Hub for onthefly training.
</figcaption>
</figure>
</div>
## Migrate `v2.1` → `v3.0`
A converter aggregates perepisode files into larger shards and writes episode offsets/metadata. Convert your dataset using the instructions below.
```bash
# Pre-release build with v3 support:
pip install "https://github.com/huggingface/lerobot/archive/33cad37054c2b594ceba57463e8f11ee374fa93c.zip"
# Convert an existing v2.1 dataset hosted on the Hub:
python -m lerobot.datasets.v30.convert_dataset_v21_to_v30 --repo-id=<HF_USER/DATASET_ID>
```
**What it does**
- Aggregates parquet files: `episode-0000.parquet`, `episode-0001.parquet`, … → **`file-0000.parquet`**, …
- Aggregates mp4 files: `episode-0000.mp4`, `episode-0001.mp4`, … → **`file-0000.mp4`**, …
- Updates `meta/episodes/*` (chunked Parquet) with perepisode lengths, tasks, and byte/frame offsets.