Add padding keys and download_data option

lerobot/common/datasets/lerobot_dataset.py

@@ -52,6 +52,7 @@ def __init__(
         image_transforms: Callable | None = None,
         delta_timestamps: dict[list[float]] | None = None,
         tolerance_s: float = 1e-4,
+        download_data: bool = True,
         video_backend: str | None = None,
     ):
         """LeRobotDataset encapsulates 3 main things:
@@ -128,6 +129,7 @@ def __init__(
                 timestamps is separated to the next by 1/fps +/- tolerance_s. This also applies to frames
                 decoded from video files. It is also used to check that `delta_timestamps` (when provided) are
                 multiples of 1/fps. Defaults to 1e-4.
+            download_data (bool, optional): Flag to download actual data. Defaults to True.
             video_backend (str | None, optional): Video backend to use for decoding videos. There is currently
                 a single option which is the pyav decoder used by Torchvision. Defaults to pyav.
         """
@@ -139,6 +141,7 @@ def __init__(
         self.delta_timestamps = delta_timestamps
         self.episodes = episodes
         self.tolerance_s = tolerance_s
+        self.download_data = download_data
         self.video_backend = video_backend if video_backend is not None else "pyav"
         self.delta_indices = None
 
@@ -149,6 +152,13 @@ def __init__(
         self.stats = load_stats(repo_id, self._version, self.root)
         self.tasks = load_tasks(repo_id, self._version, self.root)
 
+        if not self.download_data:
+            # TODO(aliberts): Add actual support for this
+            # maybe use local_files_only=True or HF_HUB_OFFLINE=True
+            # see thread https://huggingface.slack.com/archives/C06ME3E7JUD/p1728637455476019
+            self.hf_dataset, self.episode_data_index = None, None
+            return
+
         # Load actual data
         self.download_episodes()
         self.hf_dataset = load_hf_dataset(self.root, self.data_path, self.total_episodes, self.episodes)
@@ -243,6 +253,11 @@ def camera_keys(self) -> list[str]:
         """Keys to access image and video streams from cameras (regardless of their storage method)."""
         return self.image_keys + self.video_keys
 
+    @property
+    def names(self) -> dict[list[str]]:
+        """Names of the various dimensions of vector modalities."""
+        return self.info["names"]
+
     @property
     def num_samples(self) -> int:
         """Number of samples/frames."""
@@ -275,21 +290,29 @@ def episode_length(self, episode_index) -> int:
         """Number of samples/frames for given episode."""
         return self.info["episodes"][episode_index]["length"]
 
-    def _get_query_indices(self, idx: int, ep_idx: int) -> dict[str, list[int]]:
-        # Pad values outside of current episode range
+    def _get_query_indices(self, idx: int, ep_idx: int) -> tuple[dict[str, list[int | bool]]]:
         ep_start = self.episode_data_index["from"][ep_idx]
         ep_end = self.episode_data_index["to"][ep_idx]
-        return {
+        query_indices = {
             key: [max(ep_start.item(), min(ep_end.item() - 1, idx + delta)) for delta in delta_idx]
             for key, delta_idx in self.delta_indices.items()
         }
+        padding = {  # Pad values outside of current episode range
+            f"{key}_is_pad": torch.BoolTensor(
+                [(idx + delta < ep_start.item()) | (idx + delta >= ep_end.item()) for delta in delta_idx]
+            )
+            for key, delta_idx in self.delta_indices.items()
+        }
+        return query_indices, padding
 
     def _get_query_timestamps(
-        self, query_indices: dict[str, list[int]], current_ts: float
+        self,
+        current_ts: float,
+        query_indices: dict[str, list[int]] | None = None,
     ) -> dict[str, list[float]]:
         query_timestamps = {}
         for key in self.video_keys:
-            if key in query_indices:
+            if query_indices is not None and key in query_indices:
                 timestamps = self.hf_dataset.select(query_indices[key])["timestamp"]
                 query_timestamps[key] = torch.stack(timestamps).tolist()
             else:
@@ -320,23 +343,30 @@ def _query_videos(self, query_timestamps: dict[str, list[float]], ep_idx: int) -
 
         return item
 
+    def _add_padding_keys(self, item: dict, padding: dict[str, list[bool]]) -> dict:
+        for key, val in padding.items():
+            item[key] = torch.BoolTensor(val)
+        return item
+
     def __len__(self):
         return self.num_samples
 
     def __getitem__(self, idx) -> dict:
         item = self.hf_dataset[idx]
         ep_idx = item["episode_index"].item()
 
+        query_indices = None
         if self.delta_indices is not None:
             current_ep_idx = self.episodes.index(ep_idx) if self.episodes is not None else ep_idx
-            query_indices = self._get_query_indices(idx, current_ep_idx)
+            query_indices, padding = self._get_query_indices(idx, current_ep_idx)
             query_result = self._query_hf_dataset(query_indices)
+            item = {**item, **padding}
             for key, val in query_result.items():
                 item[key] = val
 
         if len(self.video_keys) > 0:
             current_ts = item["timestamp"].item()
-            query_timestamps = self._get_query_timestamps(query_indices, current_ts)
+            query_timestamps = self._get_query_timestamps(current_ts, query_indices)
             video_frames = self._query_videos(query_timestamps, ep_idx)
             item = {**video_frames, **item}