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Py Trees

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PyTrees-ROS Ecosystem

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Documentation

[About][Docs & Demos][Releases][Installation][PyTrees-Ros Ecosystem]

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:

Sequence, Selector, Parallel composites
Blackboards for data sharing
Python generators for smarter ticking over the tree graph
Python decorators for enabling meta behaviours
Render trees to dot graphs or visualise with ascii graphs on stdout

VSCode and a py38 DevContainer on CodeSpaces will set you up with an environment for running demos, tests and/or creating PRs in less than five minutes. If you're just looking for releases, fetch them from PyPi.

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

(docker) zen@py_trees:/workspaces/py_trees$ poetry install
(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
*******************************************************************************
                                   Blackboard
*******************************************************************************

Demonstrates usage of the blackboard and related behaviours.

A sequence is populated with a few behaviours that exercise
reading and writing on the Blackboard in interesting ways.

*******************************************************************************

[DEBUG] Writer               : BlackboardWriter.__init__()
...
...

If you're really looking for something more edifying than hello world examples, walk through the ros tutorials which incrementally step through the process of building a scenario handling layer for a robot.

There are also runtime visualisation tools - refer to the py_trees_ros_viewer/README as an example implementation of the underlying py_trees_js library.

0.y.x - first open source releases
1.0.x - first stable release
1.1.x - improvements
1.2.x - improvements
2.0.x - blackboards v2 with namespaces, access permissions and key tracking
2.1.x - Chooser deprecated, api housekeeping

From ppa on Ubuntu/Bionic:

$ sudo apt install python3-py-trees

From pypi:

$ pip3 install py_trees

In a Python Virtual Environment:

$ git clone https://github.com/splintered-reality/py_trees
$ cd py_trees
$ source ./venv.bash

Build your own python3 deb:

$ git clone https://github.com/splintered-reality/py_trees
$ cd py_trees
$ source ./venv.bash
$ make deb

From the ROS2 ecosystem:

$ sudo apt install ros-<rosdistro>-py-trees

See the py_trees_ros README for the latest information on pytrees packages in the ROS ecosystem and their status.

Compatibility

Documentation

# Build Locally
$ make -C docs html

# ReadTheDocs requirements
$ poetry export -f requirements.txt --with docs -o docs/requirements.txt