robokudo.utils.tree

Behavior tree utilities for RoboKudo.

This module provides helper functions for working with py_trees behavior trees. It supports:

  • Traversing trees while excluding certain node types

  • Finding nodes by type or name

  • Setting up trees and their descendants

  • Managing parent-child relationships

  • Generating scoped names for behaviors

Dependencies:

  • py_trees for behavior tree functionality

  • py_trees_ros for ROS integration

Functions

behavior_iterate_except_type(...)

Generator similar to Behavior.iterate(). But this one doesn't traverse

find_parent_of_type(...)

Traverse the given behaviour up until we either hit the top of the tree or find a node of type parent_type.

find_children_with_name(...)

Iterate() the given composite over its children and return the first child

get_scoped_list_of_names(→ typing_extensions.List[str])

This method can generate behaviour names which represent the structure of the tree.

get_scoped_name(→ str)

Get scoped name string for behavior.

setup_with_descendants_rk(→ None)

Set up ROS behavior tree and all descendants.

setup_with_descendants_on_behavior(→ None)

Set up behavior tree node and all descendants.

fix_parent_relationship_of_childs(→ None)

Fix parent references in behavior tree.

find_root(→ py_trees.behaviour.Behaviour)

Find the root of this behavior tree

add_child_to_parent(→ uuid.UUID)

Adds the given child to the parent composite node.

add_children_to_parent(→ py_trees.behaviour.Behaviour)

Append a list of children to the current list.

Module Contents

robokudo.utils.tree.behavior_iterate_except_type(tree: py_trees.behaviour.Behaviour, child_type: typing_extensions.Type, direct_descendants: bool = False, include_tree: bool = False) → typing_extensions.Generator[py_trees.behaviour.Behaviour, None, None]

Generator similar to Behavior.iterate(). But this one doesn’t traverse nodes of a specific type. It also traverses in a post-order manner like Behavior.iterate(). @param include_tree will control if you want to include ‘tree’ itself in the enumeration, like it is done in Behavior.iterate()

Parameters:

  • tree – Root behavior to start iteration from

  • child_type – Node type to exclude from iteration

  • direct_descendants – Only iterate over direct children, defaults to False

  • include_tree – Include root node in iteration, defaults to False

Returns:

Generator yielding behavior nodes

robokudo.utils.tree.find_parent_of_type(behaviour: py_trees.behaviour.Behaviour, parent_type: typing_extensions.Type) → typing_extensions.Optional[py_trees.behaviour.Behaviour]

Traverse the given behaviour up until we either hit the top of the tree or find a node of type parent_type.

Parameters:

  • behaviour – Starting behavior node

  • parent_type – Type of parent to find

Returns:

First parent of specified type, or None if not found

robokudo.utils.tree.find_children_with_name(composite: py_trees.composites.Composite, name: str, direct_descendants: bool = False) → typing_extensions.Optional[py_trees.behaviour.Behaviour]

Iterate() the given composite over its children and return the first child with child.name == name.

Parameters:

  • composite – Parent node to search in

  • name – Name to search for

  • direct_descendants – Only search direct children, defaults to False

Returns:

First child with matching name, or None if not found

robokudo.utils.tree.get_scoped_list_of_names(behaviour: py_trees.behaviour.Behaviour, scoping_behaviour_type: typing_extensions.Type) → typing_extensions.List[str]

This method can generate behaviour names which represent the structure of the tree. For that, we can prefix (or scope) the name of the input behaviour with a scoping behaviour parent. Imagine a tree like this:

Sequence (“Z”)

Sequence (“Y”)

Behaviour (“B”)

Then get_scoped_list(b,Sequence) would return a list of the instances [B,Y,Z]

Parameters:

  • behaviour – Starting behavior node

  • scoping_behaviour_type – Type of ancestors to include

Returns:

List of behavior names from root to leaf

robokudo.utils.tree.get_scoped_name(behaviour: py_trees.behaviour.Behaviour, scoping_behaviour_type: typing_extensions.Type, delimiter: str = '/') → str

Get scoped name string for behavior.

Joins ancestor names with delimiter to create a scoped name.

Parameters:

  • behaviour – Starting behavior node

  • scoping_behaviour_type – Type of ancestors to include

  • delimiter – String to join names with, defaults to “/”

Returns:

Delimited string of ancestor names

robokudo.utils.tree.setup_with_descendants_rk(tree: py_trees_ros.trees.BehaviourTree, setup_timeout: float = 0) → None

Set up ROS behavior tree and all descendants.

Call setup(0) on all children of tree.root

Parameters:

tree – A BehaviourTree which already constains all trees that should be setup’ed

during startup. :param setup_timeout: Timeout value that is passed to the setup of each child. :return: Result of setup operation

robokudo.utils.tree.setup_with_descendants_on_behavior(tree: py_trees.behaviour.Behaviour, setup_timeout: float = 0) → None

Set up behavior tree node and all descendants.

Call setup(0) on all children of tree

Parameters:

  • tree – A Behaviour, which might also be a composition

  • setup_timeout – Timeout value that is passed to the setup of each child.

robokudo.utils.tree.fix_parent_relationship_of_childs(behavior: py_trees.behaviour.Behaviour) → None

Fix parent references in behavior tree.

Iterate top-down over this tree and reset the parent relationship for all childs. This may be required if you dynamically assign the same instance of a Behavior Tree node into different parts of the BT or also have the same instance in multiple individual Behavior Trees.

Parameters:

behavior – The behavior to start with. This is typically the root node of the tree you need to “repair”

robokudo.utils.tree.find_root(behavior: py_trees.behaviour.Behaviour) → py_trees.behaviour.Behaviour

Find the root of this behavior tree

Parameters:

behavior – The behaviour to start searching from.

Returns:

The root node of the tree

robokudo.utils.tree.add_child_to_parent(parent: py_trees.composites.Composite, child: py_trees.behaviour.Behaviour) → uuid.UUID

Adds the given child to the parent composite node.

Add a child. In contrast to the standard add_child method of py_trees, this version does not check if the parent is already set. This is currently required in dynamic PPT selection during runtime, where subtrees are (re-)introduces based on runtime queries.

Parameters:

  • parent – the composite node to add child to

  • child – child to add

Raises:

TypeError – if the child is not an instance of Behaviour

Returns:

unique id of the child

robokudo.utils.tree.add_children_to_parent(parent: py_trees.composites.Composite, children: typing_extensions.List[py_trees.behaviour.Behaviour]) → py_trees.behaviour.Behaviour

Append a list of children to the current list.

Parameters:

  • parent – the composite node to add child to

  • children – list of children to add

Returns:

parent node