Graph

class eagerx.core.graph.Graph(state)[source]

The Graph API allows users to form a graph of connected nodes and objects.

add(entities)[source]

Add nodes/objects to the graph.

Parameters:: entities (Union[NodeSpec, ResetNodeSpec, ObjectSpec, EngineSpec, List[Union[NodeSpec, ResetNodeSpec, ObjectSpec, EngineSpec]]]) – Nodes/objects to add.
Return type:: None

add_component(entry=None, action=None, observation=None)[source]

Selects an available component entry (e.g. input, output, etc…) that was not already selected.

Parameters:

entry (Optional[SpecView]) – Selects the entry, so that it can be connected.
action (Optional[str]) – Adds a disconnected action entry.
observation (Optional[str]) – Adds a disconnected observation entry.

Return type:

None

connect(source=None, target=None, action=None, observation=None, window=None, delay=None, skip=None)[source]

Connect an action/source (i.e. node/object component) to an observation/target (i.e. node/object component).

Parameters:

source (Optional[SpecView]) – Compatible source types are outputs, sensors, and states.
target (Optional[SpecView]) – Compatible target types are inputs, actuators, targets, and feedthroughs.
action (Optional[str]) – Name of the action to connect (and add).
observation (Optional[str]) – Name of the observation to connect (and add).
window (Optional[int]) –
A non-negative number that specifies the number of messages to pass to the node’s callback().
- window = 1: Only the last received input message.
- window = x > 1: The trailing last x received input messages.
- window = 0: All input messages received since the last call to the node’s callback().
Note

With window = 0, the number of input messages may vary and can even be zero.
delay (Optional[float]) – A non-negative simulated delay (seconds). This delay is ignored if simulate_delays = True in the engine’s spec().
skip (Optional[bool]) – Skip the dependency on this input during the first call to the node’s callback(). May be necessary to ensure that the connected graph is directed and acyclic.

Return type:

None

classmethod create(nodes=None, objects=None)[source]

Create a new graph with nodes and objects.

Parameters:

nodes (Union[NodeSpec, ResetNodeSpec, List[Union[NodeSpec, ResetNodeSpec]], None]) – Nodes to add.
objects (Union[ObjectSpec, List[ObjectSpec], None]) – Objects to add.

Return type:

Graph

Returns:

The graph.

disconnect(source=None, target=None, action=None, observation=None, remove=False)[source]

Disconnects a source/action from a target/observation.

Parameters:

source (Optional[SpecView]) – Compatible source types are outputs, sensors, and states.
target (Optional[SpecView]) – Compatible target types are inputs, actuators, targets, and feedthroughs.
action (Optional[str]) – Name of the action to connect (and add).
observation (Optional[str]) – Name of the observation to connect (and add).
remove (bool) – Flag to also remove observations/actions if they are left disconnected after the entry was disconnected. Actions are only removed if they are completely disconnected.

Return type:

None

get(entry=None, action=None, observation=None, parameter=None)[source]

Fetches the parameters of a node/object/action/observation.

Parameters:

entry (Union[SpecView, EntitySpec, None]) – The entry whose parameters are fetched.
action (Optional[str]) – Action name whose parameters are fetched.
observation (Optional[str]) – observation name whose parameters are fetched.
parameter (Optional[str]) – If only a single parameter needs to be fetched.

Return type:

Any

Returns:

Parameters

get_spec(name)[source]

Get Spec from the graph

Parameters:: name (str) – Name
Return type:: EntitySpec
Returns:: The specification of the entity.

gui(interactive=True, resolution=None, filename=None)[source]

Opens a graphical user interface of the graph.

Note

Requires eagerx-gui:

pip3 install eagerx-gui

Parameters:

interactive (Optional[bool]) – If True, an interactive application is launched. Otherwise, an RGB render of the GUI is returned. This could be useful when using a headless machine.
resolution (Optional[List[int]]) – Specifies the resolution of the returned render when interactive is False. If interactive is True, this argument is ignored.
filename (Optional[str]) – If provided, the GUI is rendered to an svg file with this name. If interactive is True, this argument is ignored.

Return type:

Optional[ndarray]

Returns:

RGB render of the GUI if interactive is False.

is_valid(plot=True)[source]

Checks the validity of the graph.

Checks if all selected actions, observations, inputs, actuators, targets, and feedthroughs are connected.
Checks if the graph is directed and acyclic.

Parameters:: plot – Flag to plot the graph. Can be helpful to identify cycles in the graph that break the required acyclic property.
Return type:: bool
Returns:: flag that specifies the validity of the graph.

classmethod load(file)[source]

Loads the graph state.

The state is loaded in .yaml format and contains the state of every added node, object, action, and observation and the connections between them.

Parameters:: file (str) – A string giving the name (and the file if the file isn’t in the current working directory).

reload()[source]: Reloads (ie imports) all entities in the graph.

remove(names, remove=False)[source]

Removes nodes/objects from the graph.

First, all associated connections are disconnected.
Then, removes the node/object.

Parameters:

names (Union[str, EntitySpec, List[Union[str, EntitySpec]]]) – Either the name or spec of the node/object that is to be removed.
remove (bool) – Flag to also remove observations/actions if they are left disconnected after the node/object was removed. Actions are only removed if they are completely disconnected.

Return type:

List

Returns:

list of disconnected connections.

remove_component(entry=None, action=None, observation=None, remove=False)[source]

Deselects a component entry (e.g. input, output, etc…) that was selected.

First, all associated connections are disconnected.
Then, deselects the component entry. For feedthroughs, it will also remove the corresponding output entry.

Parameters:

entry (Optional[SpecView]) – Deselects the entry.
action (Optional[str]) – Removes an action entry.
observation (Optional[str]) – Removes an observation entry
remove (bool) – Flag to also remove observations/actions if they are left disconnected after the entry was removed. Actions are only removed if they are completely disconnected.

Return type:

None

rename(new, action=None, observation=None)[source]

Renames an action/observation.

Parameters:

new (str) – New name.
action (Optional[str]) – Old action name.
observation (Optional[str]) – Old observation name.

Return type:

None

render(source, rate, processor=None, window=None, delay=None, skip=None, render_cls=None, process=0, encoding='bgr', **kwargs)[source]

Visualize rgb images produced by a node/sensor in the graph. The rgb images must be of dtype=uint8 and shape=(height, width, 3).

Parameters:

source (SpecView) – Compatible source types are outputs and sensors.
rate (float) – The rate (Hz) at which to render the images.
processor (Optional[ProcessorSpec]) – Processes the received message before passing it to the target node’s callback().
window (Optional[int]) –
A non-negative number that specifies the number of messages to pass to the node’s callback().
- window = 1: Only the last received input message.
- window = x > 1: The trailing last x received input messages.
- window = 0: All input messages received since the last call to the node’s callback().
Note

With window = 0, the number of input messages may vary and can even be zero.
delay (Optional[float]) – A non-negative simulated delay (seconds). This delay is ignored if simulate_delays = True in the engine’s spec().
skip (Optional[bool]) – Skip the dependency on this input during the first call to the node’s callback(). May be necessary to ensure that the connected graph is directed and acyclic.
render_cls (Optional[Type[Node]]) – The Node of the render node. By default, it uses the standard RenderNode. In Google colab, the ColabRender class is used.
process (int) – Process in which the render node is launched. See process for all options.
encoding (str) – The encoding (bgr or rgb) of the render source.
kwargs – Optional arguments required by the render node.

save(file)[source]

Saves the graph state.

The state is saved in .yaml format and contains the state of every added node, object, action, and observation and the connections between them.

Parameters:: file (str) – A string giving the name (and the file if the file isn’t in the current working directory).
Return type:: None

set(mapping, entry=None, action=None, observation=None, parameter=None)[source]

Sets the parameters of a node/object/action/observation.

Parameters:

mapping (Any) – Either a mapping with key = parameter, or a single value that corresponds to the optional parameter argument.
entry (Optional[SpecView]) – The entry whose parameters are mutated.
action (Optional[str]) – Action name whose parameters are mutated.
observation (Optional[str]) – observation name whose parameters are mutated.
parameter (Optional[str]) – If only a single value needs to be set. See documentation for mapping.

Return type:

None