synchros2.filters module

class synchros2.filters.Adapter

Bases: Filter

A message filter for data adaptation.

__init__(upstream: Filter, fn: Callable, *, autostart: bool = True) → None

Initializes the adapter.

Parameters:

• upstream – the upstream message filter.

• fn – a callable that takes messages as arguments and returns some

• signaled (data to be)

• returned (If none is)

• occur. (no message signaling will)

• autostart – whether to start filtering on instantiation or not.

add(*messages: Any) → None

Add messages to the filter.

class synchros2.filters.ApproximateTimeSynchronizer

Bases: TimeSynchronizerBase[ApproximateTimeSynchronizer]

A threadsafe message_filters.ApproximateTimeSynchronizer equivalent.

__init__(upstreams: Sequence[Filter], *args: Any, autostart: bool = True, **kwargs: Any) → None

Initializes the ApproximateTimeSynchronizer instance.

Parameters:

• upstreams – message filters to be synchronized.

• args – positional arguments to forward to message_filters.ApproximateTimeSynchronizer.

• autostart – whether to start filtering on instantiation or not.

• kwargs – keyword arguments to forward to message_filters.ApproximateTimeSynchronizer.

class synchros2.filters.ExactTimeSynchronizer

Bases: TimeSynchronizerBase[TimeSynchronizer]

A thread-safe message_filters.TimeSynchronizer equivalent.

__init__(upstreams: Sequence[Filter], *args: Any, autostart: bool = True, **kwargs: Any) → None

Initializes the ExactTimeSynchronizer instance.

Parameters:

• upstreams – message filters to be synchronized.

• args – positional arguments to forward to message_filters.TimeSynchronizer.

• autostart – whether to start filtering on instantiation or not.

• kwargs – keyword arguments to forward to message_filters.TimeSynchronizer.

class synchros2.filters.Filter

Bases: SimpleFilterProtocol

A threadsafe message_filters.SimpleFilter compliant message filter.

__init__(autostart: bool = True) → None

Initialize filter.

Parameters:

autostart – whether to start filtering on instantiation or not.

registerCallback(fn: Callable, *args: Any) → int

Register callable to be called on filter output.

Parameters:

• fn – callback callable.

• args – optional positional arguments to supply on call.

Returns:

a unique connection identifier.

Raises:

RuntimeError – if filter has been stopped.

signalMessage(*messages: Any) → None

Feed one or more messages to the filter.

Parameters:

messages – messages to be forwarded through the filter.

Raises:

• RuntimeError – if filter is not active

• (either not started or already stopped). –

start() → None

Start filtering.

Raises:

RuntimeError – if filtering has been stopped already.

stop() → None

Stop filtering.

Raises:

RuntimeError – if filter has not been started.

unregisterCallback(connection: int) → None

Unregister a callback.

Parameters:

connection – unique identifier for the callback.

class synchros2.filters.SimpleFilterProtocol

Bases: Protocol

Protocol for message_filters.SimpleFilter subclasses.

__init__(*args, **kwargs)

registerCallback(callback: Callable, *args: Any) → int

Register callable to be called on filter output.

signalMessage(*messages: Any) → None

Feed one or more messages to the filter.

class synchros2.filters.Subscriber

Bases: Filter

A threadsafe message_filters.Subscriber equivalent.

__init__(node: rclpy.node.Node, *args: Any, autostart: bool = True, **kwargs: Any) → None

Initializes the Subscriber instance.

Parameters:

• node – ROS 2 node to subscribe with.

• args – positional arguments to forward to rclpy.node.Node.create_subscription.

• autostart – whether to start filtering on instantiation or not.

• kwargs – keyword arguments to forward to rclpy.node.Node.create_subscription.

close() → None

Stop filtering.

Raises:

RuntimeError – if filter has not been started.

class synchros2.filters.TimeSynchronizerBase

Bases: Filter, Generic[_TimeSynchronizerType]

A base class for time synchronization filters.

__init__(time_synchronizer_type: Type[message_filters.TimeSynchronizer], upstreams: Sequence[Filter], *args: Any, autostart: bool = True, **kwargs: Any) → None

Initializes the TimeSynchronizerBase instance.

Parameters:

• time_synchronizer_type – The type of the internal time synchronizer. Note this is the actual type not an instance. This type must be or inherit from message_filters.TimeSynchronizer

• upstreams – message filters to be synchronized.

• args – positional arguments to forward to the internal time synchronizer.

• autostart – whether to start filtering on instantiation or not.

• kwargs – keyword arguments to forward to internal time synchronizer.

property upstreams: List[Filter]

Returns a list of the message filters to be synchronized

class synchros2.filters.TransformFilter

Bases: Filter

A tf2_ros driven message filter, ensuring user defined transforms’ availability.

This filter passes a stamped transform along with filtered messages, from message frame ID to the given target frame ID, looked up at the message timestamp. The message is assumed to have a header. When filtering message tuples, only the first message header is observed.

__init__(upstream: Filter, target_frame_id: str, tf_buffer: tf2_ros.Buffer, tolerance_sec: float, logger: rclpy.impl.rcutils_logger.RcutilsLogger | None = None, *, autostart: bool = True) → None

Initializes the transform filter.

Parameters:

• upstream – the upstream message filter.

• target_frame_id – the target frame ID for transforms.

• tf_buffer – a buffer of transforms to look up.

• tolerance_sec – a tolerance, in seconds, to wait for late transforms

• messages. (before abandoning any waits and filtering out the corresponding)

• logger – an optional logger to notify the yser about any errors during filtering.

• autostart – whether to start filtering on instantiation or not.

add(*messages: Any) → None

Add messages to the filter.

class synchros2.filters.Tunnel

Bases: Filter

A message filter that simply forwards messages but can be detached.

__init__(upstream: Filter, *, autostart: bool = True) → None

Initializes the tunnel.

Parameters:

• upstream – the upstream message filter.

• autostart – whether to start filtering on instantiation or not.

close() → None

Closes the tunnel, simply disconnecting it from upstream.