py_trees

Pythonic implementation of behaviour trees.

Links

README

Py Trees

[About] [What’s New?] [Documentation] [Getting Started] [Next Steps] [Releases]

About

PyTrees is a python implementation of behaviour trees designed to facilitate the rapid development of medium sized decision making engines for use in fields like robotics. Brief feature list:

Behaviours, Decorators, Sequences, Selectors, Parallels and BehaviourTree.
Blackboards for data sharing.
A useful library of behaviours, decorators and idioms.
Serialise to a dot graph or render to ascii/unicode in a terminal.
Tested on Linux and Mac (YMMV with Windows).

What’s New?

[2023-01-28] The 2.2.x Release is out! Sequences and Selectors with AND without memory.
[2023-01-28] Get Started with py_trees in under 5mins.
[2023-01-28] This is now a poetry project with configuration governed by pyproject.toml.
- The vestigial setup.py is only to assist distribution where PEP-517 is not yet well supported.

Documentation

Getting Started

You can get started on CodeSpaces (with no mismatched environment issues and in under 5mins) [1]:

Fork the project to your personal account
Click on Code -> Codespaces -> + Create a Codespace
Enter the Terminal

# Install Dependencies
(docker) zen@py_trees:/workspaces/py_trees$ poetry install

# Explore the demos
(docker) zen@py_trees:/workspaces/py_trees$ poetry shell
(py-trees-py3.8) (docker) zen@py_trees:/workspaces/py_trees$ py-trees-demo-<tab>-<tab>
py-trees-demo-action-behaviour            py-trees-demo-context-switching           py-trees-demo-logging
py-trees-demo-behaviour-lifecycle         py-trees-demo-display-modes               py-trees-demo-pick-up-where-you-left-off
py-trees-demo-blackboard                  py-trees-demo-dot-graphs                  py-trees-demo-selector
py-trees-demo-blackboard-namespaces       py-trees-demo-either-or                   py-trees-demo-sequence
py-trees-demo-blackboard-remappings       py-trees-demo-eternal-guard               py-trees-demo-tree-stewardship
(py-trees-py3.8) (docker) zen@py_trees:/workspaces/py_trees$ py-trees-demo-blackboard
...
(py-trees-py3.8) (docker) zen@py_trees:/workspaces/py_trees$ exit

# Hack some Code

# Run the Formatter, Tests, Linters and Mypy
(docker) zen@py_trees:/workspaces/py_trees$ poetry run tox -l
py38 py310 format check mypy38 mypy310
(docker) zen@py_trees:/workspaces/py_trees$ poetry run tox -e format
...
(docker) zen@py_trees:/workspaces/py_trees$ poetry run tox -e py38
...
(docker) zen@py_trees:/workspaces/py_trees$ poetry run tox -e check
...

# Contribute a PR!
# https://github.com/splintered-reality/py_trees/blob/devel/CONTRIBUTING.md

[1] All of the above will, of course, work in a local environment if you have poetry installed. If you’re using VSCode you don’t even need that, just reopen the project in the devcontainer and be froody.

Next Steps

On PyPi:

Examples:

ReadTheDocs - PyTrees ROS Tutorials - significantly more edifying than the demos, these incrementally walk through the process of building a decision making layer for a robot. These use ROS2 (sparsely), but merely browsing should be enlightening regardless.

Visualisation:

py_trees_js - a javascript library for building your own runtime visualisation tool

Robotics:

py_trees_ros - a tree manager and behaviours designed for use specifically with ROS2
py_trees_ros_viewer - a Qt/ROS2 implementation of py_trees_js

Releases

2.2.x - Selectors, Sequences with and without memory. Improved testing and style/type checking.
2.1.x - Chooser deprecated. API housekeeping.
2.0.x - Blackboards V2!
1.2.x - Trees can now shutdown cleanly. StatusToBlackboard and EternalGuard, Visitors get finalise().
1.1.x - Fixes for setup, tick-tock, viz.
1.0.x - Behaviours, Decorators, Composites, Blackboards, Tree Management and Viz tools.
0.y.x - First open source pre-releases.

	2.1.x	2.0.x	1.2.x	0.7.x	0.6.x
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