Improves recorder manager to support customized demo indices. (#3552)

# Description

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Current manager-based workflow leveraged recorder_manager to store demo
obs and actions to hdf5 file.
- But it only outputs successful demos and accumulates the demo index
- Not supporting customized demo index (the use case is like: replay an
existing hdf5, and store successful demos while keeping its original
demo index)

The modification in this PR:
- keeps original function, but extends to store demo with specific demo
index

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## Type of change

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applicable. -->

- New feature (non-breaking change which adds functionality)


## Screenshots

| Before | After |
| ------ | ----- |
|<img width="100" height="150" alt="Screenshot from 2025-09-25 10-20-31"
src="https://github.com/user-attachments/assets/b4af24df-2781-4ba2-8693-fd246875012b"
/>|<img width="100" height="150" alt="Screenshot from 2025-09-25
10-20-47"
src="https://github.com/user-attachments/assets/e86d3210-e205-4d6b-b83e-cf69a585743b"
/> |


## Checklist

- [x] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [ ] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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---------
Co-authored-by: ooctipus <zhengyuz@nvidia.com>

source/isaaclab/config/extension.toml

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.47.3"
+version = "0.47.4"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

 Changelog
 ---------
 
+0.47.4 (2025-10-30)
+~~~~~~~~~~~~~~~~~~~
+
+Changed
+^^^^^^^
+
+* Enhanced :meth:`~isaaclab.managers.RecorderManager.export_episodes` method to support customizable sequence of demo IDs:
+
+  - Added argument ``demo_ids`` to :meth:`~isaaclab.managers.RecorderManager.export_episodes` to accept a sequence of integers
+    for custom episode identifiers.
+
+* Enhanced :meth:`~isaaclab.utils.datasets.HDF5DatasetFileHandler.write_episode` method to support customizable episode identifiers:
+
+  - Added argument ``demo_id`` to :meth:`~isaaclab.utils.datasets.HDF5DatasetFileHandler.write_episode` to accept a custom integer
+    for episode identifier.
+
+
 0.47.3 (2025-10-22)
 ~~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/managers/recorder_manager.py

@@ -442,12 +442,16 @@ class RecorderManager(ManagerBase):
         ep_meta = self._env.cfg.get_ep_meta()
         return ep_meta
 
-    def export_episodes(self, env_ids: Sequence[int] | None = None) -> None:
+    def export_episodes(self, env_ids: Sequence[int] | None = None, demo_ids: Sequence[int] | None = None) -> None:
         """Concludes and exports the episodes for the given environment ids.
 
         Args:
             env_ids: The environment ids. Defaults to None, in which case
                 all environments are considered.
+            demo_ids: Custom identifiers for the exported episodes.
+                If provided, episodes will be named "demo_{demo_id}" in the dataset.
+                Should have the same length as env_ids if both are provided.
+                If None, uses the default sequential naming scheme. Defaults to None.
         """
         # Do nothing if no active recorder terms are provided
         if len(self.active_terms) == 0:
@@ -458,6 +462,17 @@ class RecorderManager(ManagerBase):
         if isinstance(env_ids, torch.Tensor):
             env_ids = env_ids.tolist()
 
+        # Handle demo_ids processing
+        if demo_ids is not None:
+            if isinstance(demo_ids, torch.Tensor):
+                demo_ids = demo_ids.tolist()
+            if len(demo_ids) != len(env_ids):
+                raise ValueError(f"Length of demo_ids ({len(demo_ids)}) must match length of env_ids ({len(env_ids)})")
+            # Check for duplicate demo_ids
+            if len(set(demo_ids)) != len(demo_ids):
+                duplicates = [x for i, x in enumerate(demo_ids) if demo_ids.index(x) != i]
+                raise ValueError(f"demo_ids must be unique. Found duplicates: {list(set(duplicates))}")
+
         # Export episode data through dataset exporter
         need_to_flush = False
 
@@ -468,7 +483,7 @@ class RecorderManager(ManagerBase):
             if self._failed_episode_dataset_file_handler is not None:
                 self._failed_episode_dataset_file_handler.add_env_args(ep_meta)
 
-        for env_id in env_ids:
+        for i, env_id in enumerate(env_ids):
             if env_id in self._episodes and not self._episodes[env_id].is_empty():
                 self._episodes[env_id].pre_export()
 
@@ -484,7 +499,9 @@ class RecorderManager(ManagerBase):
                     else:
                         target_dataset_file_handler = self._failed_episode_dataset_file_handler
                 if target_dataset_file_handler is not None:
-                    target_dataset_file_handler.write_episode(self._episodes[env_id])
+                    # Use corresponding demo_id if provided, otherwise None
+                    current_demo_id = demo_ids[i] if demo_ids is not None else None
+                    target_dataset_file_handler.write_episode(self._episodes[env_id], current_demo_id)
                     need_to_flush = True
                 # Update episode count
                 if episode_succeeded:

source/isaaclab/isaaclab/utils/datasets/hdf5_dataset_file_handler.py

@@ -136,18 +136,27 @@ class HDF5DatasetFileHandler(DatasetFileHandlerBase):
 
         return episode
 
-    def write_episode(self, episode: EpisodeData):
+    def write_episode(self, episode: EpisodeData, demo_id: int | None = None):
         """Add an episode to the dataset.
 
         Args:
             episode: The episode data to add.
+            demo_id: Custom index for the episode. If None, uses default index.
         """
         self._raise_if_not_initialized()
         if episode.is_empty():
             return
 
-        # create episode group based on demo count
-        h5_episode_group = self._hdf5_data_group.create_group(f"demo_{self._demo_count}")
+        # Use custom demo id if provided, otherwise use default naming
+        if demo_id is not None:
+            episode_group_name = f"demo_{demo_id}"
+        else:
+            episode_group_name = f"demo_{self._demo_count}"
+
+        # create episode group with the specified name
+        if episode_group_name in self._hdf5_data_group:
+            raise ValueError(f"Episode group '{episode_group_name}' already exists in the dataset")
+        h5_episode_group = self._hdf5_data_group.create_group(episode_group_name)
 
         # store number of steps taken
         if "actions" in episode.data:
@@ -176,8 +185,10 @@ class HDF5DatasetFileHandler(DatasetFileHandlerBase):
         # increment total step counts
         self._hdf5_data_group.attrs["total"] += h5_episode_group.attrs["num_samples"]
 
-        # increment total demo counts
-        self._demo_count += 1
+        # Only increment demo count if using default indexing
+        if demo_id is None:
+            # increment total demo counts
+            self._demo_count += 1
 
     def flush(self):
         """Flush the episode data to disk."""