fixed tensor indicies in _check_cached_episode_sufficient in lerobot_dataset.py, added test

tests/datasets/test_datasets.py

@@ -36,6 +36,8 @@ from lerobot.datasets.lerobot_dataset import (
 )
 from lerobot.datasets.utils import (
     create_branch,
+    get_hf_features_from_features,
+    hf_transform_to_torch,
     hw_to_dataset_features,
 )
 from lerobot.envs.factory import make_env_config
@@ -552,3 +554,103 @@ def test_create_branch():
 
     # Clean
     api.delete_repo(repo_id, repo_type=repo_type)
+
+
+def test_check_cached_episodes_sufficient(tmp_path, lerobot_dataset_factory):
+    """Test the _check_cached_episodes_sufficient method of LeRobotDataset."""
+    # Create a dataset with 5 episodes (0-4)
+    dataset = lerobot_dataset_factory(
+        root=tmp_path / "test",
+        total_episodes=5,
+        total_frames=200,
+        use_videos=False,
+    )
+
+    # Test hf_dataset is None
+    dataset.hf_dataset = None
+    assert dataset._check_cached_episodes_sufficient() is False
+
+    # Test hf_dataset is empty
+    import datasets
+
+    empty_features = get_hf_features_from_features(dataset.features)
+    dataset.hf_dataset = datasets.Dataset.from_dict(
+        {key: [] for key in empty_features}, features=empty_features
+    )
+    dataset.hf_dataset.set_transform(hf_transform_to_torch)
+    assert dataset._check_cached_episodes_sufficient() is False
+
+    # Restore the original dataset for remaining tests
+    dataset.hf_dataset = dataset.load_hf_dataset()
+
+    # Test all episodes requested (self.episodes = None) and all are available
+    dataset.episodes = None
+    assert dataset._check_cached_episodes_sufficient() is True
+
+    # Test specific episodes requested that are all available
+    dataset.episodes = [0, 2, 4]
+    assert dataset._check_cached_episodes_sufficient() is True
+
+    # Test request episodes that don't exist in the cached dataset
+    # Create a dataset with only episodes 0, 1, 2
+    limited_dataset = lerobot_dataset_factory(
+        root=tmp_path / "limited",
+        total_episodes=3,
+        total_frames=120,
+        use_videos=False,
+    )
+
+    # Request episodes that include non-existent ones
+    limited_dataset.episodes = [0, 1, 2, 3, 4]
+    assert limited_dataset._check_cached_episodes_sufficient() is False
+
+    # Test create a dataset with sparse episodes (e.g., only episodes 0, 2, 4)
+    # First create the full dataset structure
+    sparse_dataset = lerobot_dataset_factory(
+        root=tmp_path / "sparse",
+        total_episodes=5,
+        total_frames=200,
+        use_videos=False,
+    )
+
+    # Manually filter hf_dataset to only include episodes 0, 2, 4
+    episode_indices = sparse_dataset.hf_dataset["episode_index"]
+    mask = torch.zeros(len(episode_indices), dtype=torch.bool)
+    for ep in [0, 2, 4]:
+        mask |= torch.tensor(episode_indices) == ep
+
+    # Create a filtered dataset
+    filtered_data = {}
+    # Find image keys by checking features
+    image_keys = [key for key, ft in sparse_dataset.features.items() if ft.get("dtype") == "image"]
+
+    for key in sparse_dataset.hf_dataset.column_names:
+        values = sparse_dataset.hf_dataset[key]
+        # Filter values based on mask
+        filtered_values = [val for i, val in enumerate(values) if mask[i]]
+
+        # Convert float32 image tensors back to uint8 numpy arrays for HuggingFace dataset
+        if key in image_keys and len(filtered_values) > 0:
+            # Convert torch tensors (float32, [0, 1], CHW) back to numpy arrays (uint8, [0, 255], HWC)
+            filtered_values = [
+                (val.permute(1, 2, 0).numpy() * 255).astype(np.uint8) for val in filtered_values
+            ]
+
+        filtered_data[key] = filtered_values
+
+    sparse_dataset.hf_dataset = datasets.Dataset.from_dict(
+        filtered_data, features=get_hf_features_from_features(sparse_dataset.features)
+    )
+    sparse_dataset.hf_dataset.set_transform(hf_transform_to_torch)
+
+    # Test requesting all episodes when only some are cached
+    sparse_dataset.episodes = None
+    assert sparse_dataset._check_cached_episodes_sufficient() is False
+
+    # Test requesting only the available episodes
+    sparse_dataset.episodes = [0, 2, 4]
+    assert sparse_dataset._check_cached_episodes_sufficient() is True
+
+    # Test requesting a mix of available and unavailable episodes
+    sparse_dataset.episodes = [0, 1, 2]
+    assert sparse_dataset._check_cached_episodes_sufficient() is False