chore (docs): add docstring for processor

src/lerobot/envs/utils.py

@@ -36,11 +36,11 @@ def preprocess_observation(observations: dict[str, np.ndarray]) -> dict[str, Ten
     Returns:
         Dictionary of observation batches with keys renamed to LeRobot format and values as tensors.
     """
-    from lerobot.processor.observation_processor import ObservationProcessor
+    from lerobot.processor.observation_processor import VanillaObservationProcessor
     from lerobot.processor.pipeline import RobotProcessor, TransitionIndex
 
     # Create processor with observation processor
-    processor = RobotProcessor([ObservationProcessor()])
+    processor = RobotProcessor([VanillaObservationProcessor()])
 
     # Create transition tuple and process
     transition = (observations, None, None, None, None, None, None)

src/lerobot/processor/__init__.py

@@ -16,19 +16,35 @@
 from .normalize_processor import NormalizationProcessor
 from .observation_processor import (
     ImageProcessor,
-    ObservationProcessor,
     StateProcessor,
+    VanillaObservationProcessor,
+)
+from .pipeline import (
+    ActionProcessor,
+    DoneProcessor,
+    EnvTransition,
+    InfoProcessor,
+    ObservationProcessor,
+    ProcessorStep,
+    RewardProcessor,
+    RobotProcessor,
+    TruncatedProcessor,
 )
-from .pipeline import EnvTransition, ProcessorStep, RobotProcessor
 from .rename_processor import RenameProcessor
 
 __all__ = [
-    "RobotProcessor",
+    "ActionProcessor",
-    "ProcessorStep",
+    "DoneProcessor",
     "EnvTransition",
     "ImageProcessor",
-    "StateProcessor",
+    "InfoProcessor",
-    "ObservationProcessor",
     "NormalizationProcessor",
+    "ObservationProcessor",
+    "ProcessorStep",
     "RenameProcessor",
+    "RewardProcessor",
+    "RobotProcessor",
+    "StateProcessor",
+    "TruncatedProcessor",
+    "VanillaObservationProcessor",
 ]

src/lerobot/processor/observation_processor.py

@@ -181,7 +181,7 @@ class StateProcessor:
 
 @dataclass
 @ProcessorStepRegistry.register(name="observation_processor")
-class ObservationProcessor:
+class VanillaObservationProcessor:
     """Complete observation processor that combines image and state processing.
 
     This processor replicates the functionality of the original preprocess_observation

src/lerobot/processor/pipeline.py

@@ -467,7 +467,35 @@ class RobotProcessor(ModelHubMixin):
 
 
 class ObservationProcessor:
+    """Base class for processors that modify only the observation component of a transition.
+
+    Subclasses should override the `observation` method to implement custom observation processing.
+    This class handles the boilerplate of extracting and reinserting the processed observation
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class MyObservationScaler(ObservationProcessor):
+            def __init__(self, scale_factor):
+                self.scale_factor = scale_factor
+
+            def observation(self, observation):
+                return observation * self.scale_factor
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific observation processing logic.
+    """
+
     def observation(self, observation):
+        """Process the observation component.
+
+        Args:
+            observation: The observation to process
+
+        Returns:
+            The processed observation
+        """
         return observation
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
@@ -478,7 +506,36 @@ class ObservationProcessor:
 
 
 class ActionProcessor:
+    """Base class for processors that modify only the action component of a transition.
+
+    Subclasses should override the `action` method to implement custom action processing.
+    This class handles the boilerplate of extracting and reinserting the processed action
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class ActionClipping(ActionProcessor):
+            def __init__(self, min_val, max_val):
+                self.min_val = min_val
+                self.max_val = max_val
+
+            def action(self, action):
+                return np.clip(action, self.min_val, self.max_val)
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific action processing logic.
+    """
+
     def action(self, action):
+        """Process the action component.
+
+        Args:
+            action: The action to process
+
+        Returns:
+            The processed action
+        """
         return action
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
@@ -489,7 +546,35 @@ class ActionProcessor:
 
 
 class RewardProcessor:
+    """Base class for processors that modify only the reward component of a transition.
+
+    Subclasses should override the `reward` method to implement custom reward processing.
+    This class handles the boilerplate of extracting and reinserting the processed reward
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class RewardScaler(RewardProcessor):
+            def __init__(self, scale_factor):
+                self.scale_factor = scale_factor
+
+            def reward(self, reward):
+                return reward * self.scale_factor
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific reward processing logic.
+    """
+
     def reward(self, reward):
+        """Process the reward component.
+
+        Args:
+            reward: The reward to process
+
+        Returns:
+            The processed reward
+        """
         return reward
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
@@ -505,7 +590,40 @@ class RewardProcessor:
 
 
 class DoneProcessor:
+    """Base class for processors that modify only the done flag of a transition.
+
+    Subclasses should override the `done` method to implement custom done flag processing.
+    This class handles the boilerplate of extracting and reinserting the processed done flag
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class TimeoutDone(DoneProcessor):
+            def __init__(self, max_steps):
+                self.steps = 0
+                self.max_steps = max_steps
+
+            def done(self, done):
+                self.steps += 1
+                return done or self.steps >= self.max_steps
+
+            def reset(self):
+                self.steps = 0
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific done flag processing logic.
+    """
+
     def done(self, done):
+        """Process the done flag.
+
+        Args:
+            done: The done flag to process
+
+        Returns:
+            The processed done flag
+        """
         return done
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
@@ -522,7 +640,36 @@ class DoneProcessor:
 
 
 class TruncatedProcessor:
+    """Base class for processors that modify only the truncated flag of a transition.
+
+    Subclasses should override the `truncated` method to implement custom truncated flag processing.
+    This class handles the boilerplate of extracting and reinserting the processed truncated flag
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class EarlyTruncation(TruncatedProcessor):
+            def __init__(self, threshold):
+                self.threshold = threshold
+
+            def truncated(self, truncated):
+                # Additional truncation condition
+                return truncated or some_condition > self.threshold
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific truncated flag processing logic.
+    """
+
     def truncated(self, truncated):
+        """Process the truncated flag.
+
+        Args:
+            truncated: The truncated flag to process
+
+        Returns:
+            The processed truncated flag
+        """
         return truncated
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
@@ -540,7 +687,41 @@ class TruncatedProcessor:
 
 
 class InfoProcessor:
+    """Base class for processors that modify only the info dictionary of a transition.
+
+    Subclasses should override the `info` method to implement custom info processing.
+    This class handles the boilerplate of extracting and reinserting the processed info
+    into the transition tuple, eliminating the need to implement the `__call__` method in subclasses.
+
+    Example:
+        ```python
+        class InfoAugmenter(InfoProcessor):
+            def __init__(self):
+                self.step_count = 0
+
+            def info(self, info):
+                info = info.copy()  # Create a copy to avoid modifying the original
+                info['steps'] = self.step_count
+                self.step_count += 1
+                return info
+
+            def reset(self):
+                self.step_count = 0
+        ```
+
+    By inheriting from this class, you avoid writing repetitive code to handle transition tuple
+    manipulation, focusing only on the specific info dictionary processing logic.
+    """
+
     def info(self, info):
+        """Process the info dictionary.
+
+        Args:
+            info: The info dictionary to process
+
+        Returns:
+            The processed info dictionary
+        """
         return info
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:

tests/processor/test_observation_processor.py

@@ -20,8 +20,8 @@ import torch
 
 from lerobot.processor.observation_processor import (
     ImageProcessor,
-    ObservationProcessor,
     StateProcessor,
+    VanillaObservationProcessor,
 )
 
 
@@ -262,7 +262,7 @@ def test_no_states_in_observation():
 
 def test_complete_observation_processing():
     """Test processing a complete observation with both images and states."""
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     # Create mock data
     image = np.random.randint(0, 256, size=(32, 32, 3), dtype=np.uint8)
@@ -299,7 +299,7 @@ def test_complete_observation_processing():
 
 def test_image_only_processing():
     """Test processing observation with only images."""
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     image = np.random.randint(0, 256, size=(64, 64, 3), dtype=np.uint8)
     observation = {"pixels": image}
@@ -314,7 +314,7 @@ def test_image_only_processing():
 
 def test_state_only_processing():
     """Test processing observation with only states."""
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     agent_pos = np.array([1.0, 2.0], dtype=np.float32)
     observation = {"agent_pos": agent_pos}
@@ -329,7 +329,7 @@ def test_state_only_processing():
 
 def test_empty_observation():
     """Test processing empty observation."""
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     observation = {}
     transition = (observation, None, None, None, None, None, None)
@@ -344,7 +344,7 @@ def test_custom_sub_processors():
     """Test ObservationProcessor with custom sub-processors."""
     image_proc = ImageProcessor()
     state_proc = StateProcessor()
-    processor = ObservationProcessor(image_processor=image_proc, state_processor=state_proc)
+    processor = VanillaObservationProcessor(image_processor=image_proc, state_processor=state_proc)
 
     # Should use the provided processors
     assert processor.image_processor is image_proc
@@ -356,7 +356,7 @@ def test_equivalent_to_original_function():
     # Import the original function for comparison
     from lerobot.envs.utils import preprocess_observation
 
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     # Create test data similar to what the original function expects
     image = np.random.randint(0, 256, size=(64, 64, 3), dtype=np.uint8)
@@ -383,7 +383,7 @@ def test_equivalent_with_image_dict():
     """Test equivalence with dictionary of images."""
     from lerobot.envs.utils import preprocess_observation
 
-    processor = ObservationProcessor()
+    processor = VanillaObservationProcessor()
 
     # Create test data with multiple cameras
     image1 = np.random.randint(0, 256, size=(32, 32, 3), dtype=np.uint8)