misbehave

Misbehave is a Python behavior tree implementation. A behavior tree is a design pattern that breaks complex state-based actions into their component parts to improve readability and re-usability for autonomous agents. A good starting place to understand them is [here]](https://www.gamasutra.com/blogs/ChrisSimpson/20140717/221339/Behavior_trees_for_AI_How_they_work.php).

Misbehave focused on python language features not available in other languages, so some of the common features of AI design are missing by default. The rest of this document is lightly hedged in its language as behavior trees can be useful for video games or robots.

How to use Misbehave

A node in a Misbehave behavior tree is simply a callable. While the ones provided with this library are classes, you can use functions or closures to define them.

The signature of a node's function is simple:

def MyNode(actor: Any, context: Any) -> misbehave.State
    # Perform actions here.

An actor is an object representing the thing the behavior tree is controlling. In a video game, this would be the mob object.

The context is available for providing access to things like sensors, controls, other code objects representing things in space. If you don't need them, you can pass None here.

An example of a tree might look like this in your code:

class MyActor():
    tree = misbehave.selector.Sequence(
        misbehave.action.IncreaseValue("behavior_tree_runs"),
        my_actions.MoveForward(10),
        my_actions.Rotate(90)
    )
    behavior_tree_runs = 0

This simple tree keeps track of how many times the entire tree was run, and then moves the actor in a square. You must implement the specifics of the actions here.

Development

Misbehave requires Python 3.6 or later.

To work on misbehave, after forking and cloning locally, you'll want to setup a virtual environment. You'll notice we don't have any requirement files: all requirements are listed in setup.cfg either as setup_requires or as extras.

In your project directory, with your virtual environment active:

python -m pip install -e .[dev, tests]

If you do not do an editable install of misbehave, misbehave.version will be missing and the library will fail to work.

Other than that, we are ready for PEP 518 and 517, so if you're using a build tool that supports them, feel free!

It is strongly encouraged that you run black on the misbehave directory and then pytest before commiting to any working branch. Failure to lint will disqualify a PR.