re_data_loader/
loader_lerobot.rs

use std::sync::mpsc::Sender;
use std::sync::Arc;
use std::thread;

use anyhow::{anyhow, Context as _};
use arrow::array::{
    ArrayRef, BinaryArray, FixedSizeListArray, Int64Array, RecordBatch, StringArray, StructArray,
};
use arrow::compute::cast;
use arrow::datatypes::{DataType, Field};
use itertools::Either;
use re_arrow_util::ArrowArrayDowncastRef as _;
use re_chunk::{external::nohash_hasher::IntMap, TimelineName};
use re_chunk::{
    ArrowArray, Chunk, ChunkId, EntityPath, RowId, TimeColumn, TimeInt, TimePoint, Timeline,
};

use re_log_types::{ApplicationId, StoreId};
use re_types::archetypes::{
    AssetVideo, DepthImage, EncodedImage, TextDocument, VideoFrameReference,
};
use re_types::components::{Name, Scalar, VideoTimestamp};
use re_types::{Archetype, Component, ComponentBatch};

use crate::lerobot::{
    is_lerobot_dataset, is_v1_lerobot_dataset, DType, EpisodeIndex, Feature, LeRobotDataset,
    TaskIndex,
};
use crate::load_file::prepare_store_info;
use crate::{DataLoader, DataLoaderError, LoadedData};

/// Columns in the `LeRobot` dataset schema that we do not visualize in the viewer, and thus ignore.
const LEROBOT_DATASET_IGNORED_COLUMNS: &[&str] =
    &["episode_index", "index", "frame_index", "timestamp"];

/// Only supports `LeRobot` datasets that are in a supported version format.
/// Datasets from unsupported versions won't load.
const LEROBOT_DATASET_SUPPORTED_VERSIONS: &[&str] = &["v2.0", "v2.1"];

/// A [`DataLoader`] for `LeRobot` datasets.
///
/// An example dataset which can be loaded can be found on Hugging Face: [lerobot/pusht_image](https://huggingface.co/datasets/lerobot/pusht_image)
pub struct LeRobotDatasetLoader;

impl DataLoader for LeRobotDatasetLoader {
    fn name(&self) -> String {
        "LeRobotDatasetLoader".into()
    }

    fn load_from_path(
        &self,
        settings: &crate::DataLoaderSettings,
        filepath: std::path::PathBuf,
        tx: Sender<LoadedData>,
    ) -> Result<(), DataLoaderError> {
        if !is_lerobot_dataset(&filepath) {
            return Err(DataLoaderError::Incompatible(filepath));
        }

        if is_v1_lerobot_dataset(&filepath) {
            re_log::error!("LeRobot 'v1.x' dataset format is unsupported.");
            return Ok(());
        }

        let dataset = LeRobotDataset::load_from_directory(&filepath)
            .map_err(|err| anyhow!("Loading LeRobot dataset failed: {err}"))?;

        if !LEROBOT_DATASET_SUPPORTED_VERSIONS
            .contains(&dataset.metadata.info.codebase_version.as_str())
        {
            re_log::error!(
                "LeRobot '{}' dataset format is unsupported.",
                dataset.metadata.info.codebase_version
            );
            return Ok(());
        }

        let application_id = settings
            .application_id
            .clone()
            .unwrap_or(ApplicationId(filepath.display().to_string()));

        // NOTE(1): `spawn` is fine, this whole function is native-only.
        // NOTE(2): this must spawned on a dedicated thread to avoid a deadlock!
        // `load` will spawn a bunch of loaders on the common rayon thread pool and wait for
        // their response via channels: we cannot be waiting for these responses on the
        // common rayon thread pool.
        thread::Builder::new()
            .name(format!("load_and_stream({filepath:?}"))
            .spawn({
                move || {
                    re_log::info!(
                        "Loading LeRobot dataset from {:?}, with {} episode(s)",
                        dataset.path,
                        dataset.metadata.episodes.len(),
                    );
                    load_and_stream(&dataset, &application_id, &tx);
                }
            })
            .with_context(|| {
                format!("Failed to spawn IO thread to load LeRobot dataset {filepath:?} ")
            })?;

        Ok(())
    }

    fn load_from_file_contents(
        &self,
        _settings: &crate::DataLoaderSettings,
        filepath: std::path::PathBuf,
        _contents: std::borrow::Cow<'_, [u8]>,
        _tx: Sender<LoadedData>,
    ) -> Result<(), DataLoaderError> {
        Err(DataLoaderError::Incompatible(filepath))
    }
}

fn load_and_stream(
    dataset: &LeRobotDataset,
    application_id: &ApplicationId,
    tx: &Sender<crate::LoadedData>,
) {
    // set up all recordings
    let episodes = prepare_episode_chunks(dataset, application_id, tx);

    for (episode, store_id) in &episodes {
        // log episode data to its respective recording
        match load_episode(dataset, *episode) {
            Ok(chunks) => {
                let properties = re_types::archetypes::RecordingProperties::new()
                    .with_name(format!("Episode {}", episode.0));

                debug_assert!(TimePoint::default().is_static());
                let Ok(initial) = Chunk::builder(EntityPath::recording_properties())
                    .with_archetype(RowId::new(), TimePoint::default(), &properties)
                    .build()
                else {
                    re_log::error!(
                        "Failed to build recording properties chunk for episode {}",
                        episode.0
                    );
                    return;
                };

                for chunk in std::iter::once(initial).chain(chunks.into_iter()) {
                    let data = LoadedData::Chunk(
                        LeRobotDatasetLoader::name(&LeRobotDatasetLoader),
                        store_id.clone(),
                        chunk,
                    );

                    if tx.send(data).is_err() {
                        break; // The other end has decided to hang up, not our problem.
                    }
                }
            }
            Err(err) => {
                re_log::warn!(
                    "Failed to load episode {} from LeRobot dataset: {err}",
                    episode.0
                );
            }
        }
    }
}

/// Prepare the viewer for all episodes, by sending out a [`SetStoreInfo`](`re_log_types::SetStoreInfo`)
/// [`LogMsg`](`re_log_types::LogMsg`) for each episode.
fn prepare_episode_chunks(
    dataset: &LeRobotDataset,
    application_id: &ApplicationId,
    tx: &Sender<crate::LoadedData>,
) -> Vec<(EpisodeIndex, StoreId)> {
    let mut store_ids = vec![];

    for episode in &dataset.metadata.episodes {
        let episode = episode.index;

        let store_id = StoreId::from_string(
            re_log_types::StoreKind::Recording,
            format!("episode_{}", episode.0),
        );
        let set_store_info = LoadedData::LogMsg(
            LeRobotDatasetLoader::name(&LeRobotDatasetLoader),
            prepare_store_info(
                application_id.clone(),
                &store_id,
                re_log_types::FileSource::Sdk,
            ),
        );

        if tx.send(set_store_info).is_err() {
            break;
        }

        store_ids.push((episode, store_id.clone()));
    }

    store_ids
}

/// Loads a single episode from a `LeRobot` dataset and converts it into a collection of Rerun chunks.
///
/// This function processes an episode from the dataset by extracting the relevant data columns and
/// converting them into appropriate Rerun data structures. It handles different types of data
/// (videos, images, scalar values, etc.) based on their data type specifications in the dataset metadata.
pub fn load_episode(
    dataset: &LeRobotDataset,
    episode: EpisodeIndex,
) -> Result<Vec<Chunk>, DataLoaderError> {
    let data = dataset
        .read_episode_data(episode)
        .map_err(|err| anyhow!("Reading data for episode {} failed: {err}", episode.0))?;

    let frame_indices = data
        .column_by_name("frame_index")
        .ok_or_else(|| anyhow!("Failed to get frame index column in LeRobot dataset"))?
        .clone();

    let timeline = re_log_types::Timeline::new_sequence("frame_index");
    let times: &arrow::buffer::ScalarBuffer<i64> = frame_indices
        .downcast_array_ref::<Int64Array>()
        .ok_or_else(|| anyhow!("LeRobot dataset frame indices are of an unexpected type"))?
        .values();

    let time_column = re_chunk::TimeColumn::new(None, timeline, times.clone());
    let timelines = std::iter::once((*timeline.name(), time_column.clone())).collect();

    let mut chunks = Vec::new();

    for (feature_key, feature) in dataset
        .metadata
        .info
        .features
        .iter()
        .filter(|(key, _)| !LEROBOT_DATASET_IGNORED_COLUMNS.contains(&key.as_str()))
    {
        match feature.dtype {
            DType::Video => {
                chunks.extend(load_episode_video(
                    dataset,
                    feature_key,
                    episode,
                    &timeline,
                    time_column.clone(),
                )?);
            }

            DType::Image => {
                let num_channels = feature.channel_dim();

                match num_channels {
                    1 => chunks.extend(load_episode_depth_images(feature_key, &timeline, &data)?),
                    3 => chunks.extend(load_episode_images(feature_key, &timeline, &data)?),
                    _ => re_log::warn_once!(
                        "Unsupported channel count {num_channels} (shape: {:?}) for LeRobot dataset; Only 1- and 3-channel images are supported",
                        feature.shape
                    ),
                };
            }
            DType::Int64 if feature_key == "task_index" => {
                // special case int64 task_index columns
                // this always refers to the task description in the dataset metadata.
                chunks.extend(log_episode_task(dataset, &timeline, &data)?);
            }
            DType::Int16 | DType::Int64 | DType::Bool | DType::String => {
                re_log::warn_once!(
                    "Loading LeRobot feature ({feature_key}) of dtype `{:?}` into Rerun is not yet implemented",
                    feature.dtype
                );
            }
            DType::Float32 | DType::Float64 => {
                chunks.extend(load_scalar(feature_key, feature, &timelines, &data)?);
            }
        }
    }

    Ok(chunks)
}

fn log_episode_task(
    dataset: &LeRobotDataset,
    timeline: &Timeline,
    data: &RecordBatch,
) -> Result<impl ExactSizeIterator<Item = Chunk>, DataLoaderError> {
    let task_indices = data
        .column_by_name("task_index")
        .and_then(|c| c.downcast_array_ref::<Int64Array>())
        .with_context(|| "Failed to get task_index field from dataset!")?;

    let mut chunk = Chunk::builder("task".into());
    let mut row_id = RowId::new();
    let mut time_int = TimeInt::ZERO;

    for task_index in task_indices {
        let Some(task) = task_index
            .and_then(|i| usize::try_from(i).ok())
            .and_then(|i| dataset.task_by_index(TaskIndex(i)))
        else {
            // if there is no valid task for the current frame index, we skip it.
            time_int = time_int.inc();
            continue;
        };

        let timepoint = TimePoint::default().with(*timeline, time_int);
        let text = TextDocument::new(task.task.clone());
        chunk = chunk.with_archetype(row_id, timepoint, &text);

        row_id = row_id.next();
        time_int = time_int.inc();
    }

    Ok(std::iter::once(chunk.build()?))
}

fn load_episode_images(
    observation: &str,
    timeline: &Timeline,
    data: &RecordBatch,
) -> Result<impl ExactSizeIterator<Item = Chunk>, DataLoaderError> {
    let image_bytes = data
        .column_by_name(observation)
        .and_then(|c| c.downcast_array_ref::<StructArray>())
        .and_then(|a| a.column_by_name("bytes"))
        .and_then(|a| a.downcast_array_ref::<BinaryArray>())
        .with_context(|| format!("Failed to get binary data from image feature: {observation}"))?;

    let mut chunk = Chunk::builder(observation.into());
    let mut row_id = RowId::new();

    for frame_idx in 0..image_bytes.len() {
        let img_buffer = image_bytes.value(frame_idx);
        let encoded_image = EncodedImage::from_file_contents(img_buffer.to_owned());
        let timepoint = TimePoint::default().with(*timeline, frame_idx as i64);
        chunk = chunk.with_archetype(row_id, timepoint, &encoded_image);

        row_id = row_id.next();
    }

    Ok(std::iter::once(chunk.build().with_context(|| {
        format!("Failed to build image chunk for image: {observation}")
    })?))
}

fn load_episode_depth_images(
    observation: &str,
    timeline: &Timeline,
    data: &RecordBatch,
) -> Result<impl ExactSizeIterator<Item = Chunk>, DataLoaderError> {
    let image_bytes = data
        .column_by_name(observation)
        .and_then(|c| c.downcast_array_ref::<StructArray>())
        .and_then(|a| a.column_by_name("bytes"))
        .and_then(|a| a.downcast_array_ref::<BinaryArray>())
        .with_context(|| format!("Failed to get binary data from image feature: {observation}"))?;

    let mut chunk = Chunk::builder(observation.into());
    let mut row_id = RowId::new();

    for frame_idx in 0..image_bytes.len() {
        let img_buffer = image_bytes.value(frame_idx);
        let depth_image = DepthImage::from_file_contents(img_buffer.to_owned())
            .map_err(|err| anyhow!("Failed to decode image: {err}"))?;

        let timepoint = TimePoint::default().with(*timeline, frame_idx as i64);
        chunk = chunk.with_archetype(row_id, timepoint, &depth_image);

        row_id = row_id.next();
    }

    Ok(std::iter::once(chunk.build().with_context(|| {
        format!("Failed to build image chunk for image: {observation}")
    })?))
}

fn load_episode_video(
    dataset: &LeRobotDataset,
    observation: &str,
    episode: EpisodeIndex,
    timeline: &Timeline,
    time_column: TimeColumn,
) -> Result<impl ExactSizeIterator<Item = Chunk>, DataLoaderError> {
    let contents = dataset
        .read_episode_video_contents(observation, episode)
        .with_context(|| format!("Reading video contents for episode {episode:?} failed!"))?;

    let video_asset = AssetVideo::new(contents.into_owned());
    let entity_path = observation;

    let video_frame_reference_chunk = match video_asset.read_frame_timestamps_nanos() {
        Ok(frame_timestamps_nanos) => {
            let frame_timestamps_nanos: arrow::buffer::ScalarBuffer<i64> =
                frame_timestamps_nanos.into();

            let video_timestamps = frame_timestamps_nanos
                .iter()
                .take(time_column.num_rows())
                .copied()
                .map(VideoTimestamp::from_nanos)
                .collect::<Vec<_>>();

            let video_timestamp_batch = &video_timestamps as &dyn ComponentBatch;
            let video_timestamp_list_array = video_timestamp_batch
                .to_arrow_list_array()
                .map_err(re_chunk::ChunkError::from)?;

            // Indicator column.
            let video_frame_reference_indicators =
                <VideoFrameReference as Archetype>::Indicator::new_array(video_timestamps.len());
            let video_frame_reference_indicators_list_array = video_frame_reference_indicators
                .to_arrow_list_array()
                .map_err(re_chunk::ChunkError::from)?;

            Some(Chunk::from_auto_row_ids(
                re_chunk::ChunkId::new(),
                entity_path.into(),
                std::iter::once((*timeline.name(), time_column)).collect(),
                [
                    (
                        VideoFrameReference::indicator().descriptor.clone(),
                        video_frame_reference_indicators_list_array,
                    ),
                    (
                        video_timestamp_batch.descriptor().into_owned(),
                        video_timestamp_list_array,
                    ),
                ]
                .into_iter()
                .collect(),
            )?)
        }
        Err(err) => {
            re_log::warn_once!(
                "Failed to read frame timestamps from episode {episode:?} video: {err}"
            );
            None
        }
    };

    // Put video asset into its own (static) chunk since it can be fairly large.
    let video_asset_chunk = Chunk::builder(entity_path.into())
        .with_archetype(RowId::new(), TimePoint::default(), &video_asset)
        .build()?;

    if let Some(video_frame_reference_chunk) = video_frame_reference_chunk {
        Ok(Either::Left(
            [video_asset_chunk, video_frame_reference_chunk].into_iter(),
        ))
    } else {
        // Still log the video asset, but don't include video frames.
        Ok(Either::Right(std::iter::once(video_asset_chunk)))
    }
}

/// Helper type similar to [`Either`], but with 3 variants.
enum ScalarChunkIterator {
    Empty(std::iter::Empty<Chunk>),
    Batch(Box<dyn ExactSizeIterator<Item = Chunk>>),
    Single(std::iter::Once<Chunk>),
}

impl Iterator for ScalarChunkIterator {
    type Item = Chunk;

    fn next(&mut self) -> Option<Self::Item> {
        match self {
            Self::Empty(iter) => iter.next(),
            Self::Batch(iter) => iter.next(),
            Self::Single(iter) => iter.next(),
        }
    }
}

impl ExactSizeIterator for ScalarChunkIterator {}

fn load_scalar(
    feature_key: &str,
    feature: &Feature,
    timelines: &IntMap<TimelineName, TimeColumn>,
    data: &RecordBatch,
) -> Result<ScalarChunkIterator, DataLoaderError> {
    let field = data
        .schema_ref()
        .field_with_name(feature_key)
        .with_context(|| {
            format!("Failed to get field for feature {feature_key} from parquet file")
        })?;

    let entity_path = EntityPath::parse_forgiving(field.name());

    match field.data_type() {
        DataType::FixedSizeList(_, _) => {
            let fixed_size_array = data
                .column_by_name(feature_key)
                .and_then(|col| col.downcast_array_ref::<FixedSizeListArray>())
                .ok_or_else(|| {
                    DataLoaderError::Other(anyhow!(
                        "Failed to downcast feature to FixedSizeListArray"
                    ))
                })?;

            let batch_chunks =
                make_scalar_batch_entity_chunks(entity_path, feature, timelines, fixed_size_array)?;
            Ok(ScalarChunkIterator::Batch(Box::new(batch_chunks)))
        }
        DataType::Float32 => {
            let feature_data = data.column_by_name(feature_key).ok_or_else(|| {
                DataLoaderError::Other(anyhow!(
                    "Failed to get LeRobot dataset column data for: {:?}",
                    field.name()
                ))
            })?;

            let sliced = extract_scalar_slices_as_f64(feature_data).with_context(|| {
                format!("Failed to cast scalar feature {entity_path} to Float64")
            })?;

            Ok(ScalarChunkIterator::Single(std::iter::once(
                make_scalar_entity_chunk(entity_path, timelines, &sliced)?,
            )))
        }
        _ => {
            re_log::warn_once!(
                "Tried logging scalar {} with unsupported dtype: {}",
                field.name(),
                field.data_type()
            );
            Ok(ScalarChunkIterator::Empty(std::iter::empty()))
        }
    }
}

fn make_scalar_batch_entity_chunks(
    entity_path: EntityPath,
    feature: &Feature,
    timelines: &IntMap<TimelineName, TimeColumn>,
    data: &FixedSizeListArray,
) -> Result<impl ExactSizeIterator<Item = Chunk>, DataLoaderError> {
    let num_elements = data.value_length() as usize;

    let mut chunks = Vec::with_capacity(num_elements);

    let sliced = extract_list_elements_as_f64(data)
        .with_context(|| format!("Failed to cast scalar feature {entity_path} to Float64"))?;

    chunks.push(make_scalar_entity_chunk(
        entity_path.clone(),
        timelines,
        &sliced,
    )?);

    // If we have names for this feature, we insert a single static chunk containing the names.
    if let Some(names) = feature.names.clone() {
        let names: Vec<_> = (0..data.value_length() as usize)
            .map(|idx| names.name_for_index(idx))
            .collect();

        chunks.push(
            Chunk::builder(entity_path)
                .with_row(
                    RowId::new(),
                    TimePoint::default(),
                    std::iter::once((
                        <Name as Component>::descriptor().clone(),
                        Arc::new(StringArray::from_iter(names)) as Arc<dyn ArrowArray>,
                    )),
                )
                .build()?,
        );
    }

    Ok(chunks.into_iter())
}

fn make_scalar_entity_chunk(
    entity_path: EntityPath,
    timelines: &IntMap<TimelineName, TimeColumn>,
    sliced_data: &[ArrayRef],
) -> Result<Chunk, DataLoaderError> {
    let data_arrays = sliced_data
        .iter()
        .map(|e| Some(e.as_ref()))
        .collect::<Vec<_>>();

    let data_field_inner = Field::new("item", DataType::Float64, true /* nullable */);
    #[allow(clippy::unwrap_used)] // we know we've given the right field type
    let data_field_array: arrow::array::ListArray =
        re_arrow_util::arrays_to_list_array(data_field_inner.data_type().clone(), &data_arrays)
            .unwrap();

    Ok(Chunk::from_auto_row_ids(
        ChunkId::new(),
        entity_path,
        timelines.clone(),
        std::iter::once((
            <Scalar as Component>::descriptor().clone(),
            data_field_array,
        ))
        .collect(),
    )?)
}

fn extract_scalar_slices_as_f64(data: &ArrayRef) -> anyhow::Result<Vec<ArrayRef>> {
    // cast the slice to f64 first, as scalars need an f64
    let scalar_values = cast(&data, &DataType::Float64)
        .with_context(|| format!("Failed to cast {:?} to Float64", data.data_type()))?;

    Ok((0..data.len())
        .map(|idx| scalar_values.slice(idx, 1))
        .collect::<Vec<_>>())
}

fn extract_list_elements_as_f64(data: &FixedSizeListArray) -> anyhow::Result<Vec<ArrayRef>> {
    (0..data.len())
        .map(|idx| {
            cast(&data.value(idx), &DataType::Float64)
                .with_context(|| format!("Failed to cast {:?} to Float64", data.data_type()))
        })
        .collect::<Result<Vec<_>, _>>()
}
re_data_loader/loader_lerobot.rs

re_data_loader/
loader_lerobot.rs
