PyBBN

PyBBN is Python library for Bayesian Belief Networks (BBNs) exact inference using the junction tree algorithm or Probability Propagation in Trees of Clusters. The implementation is taken directly from C. Huang and A. Darwiche, "Inference in Belief Networks: A Procedural Guide," in International Journal of Approximate Reasoning, vol. 15, pp. 225--263, 1999. Additionally, there is the ability to generate singly- and multi-connected graphs, which is taken from JS Ide and FG Cozman, "Random Generation of Bayesian Network," in Advances in Artificial Intelligence, Lecture Notes in Computer Science, vol 2507. There is also the option to generate sample data from your BBN. This synthetic data may be summarized to generate your posterior marginal probabilities and work as a form of approximate inference. Lastly, we have added Pearl's do-operator for causal inference.

Exact Inference Usage

Below is an example code to create a Bayesian Belief Network, transform it into a join tree, and then set observation evidence. The last line prints the marginal probabilities for each node.

from pybbn.graph.dag import Bbn
from pybbn.graph.edge import Edge, EdgeType
from pybbn.graph.jointree import EvidenceBuilder
from pybbn.graph.node import BbnNode
from pybbn.graph.variable import Variable
from pybbn.pptc.inferencecontroller import InferenceController

# create the nodes
a = BbnNode(Variable(0, 'a', ['on', 'off']), [0.5, 0.5])
b = BbnNode(Variable(1, 'b', ['on', 'off']), [0.5, 0.5, 0.4, 0.6])
c = BbnNode(Variable(2, 'c', ['on', 'off']), [0.7, 0.3, 0.2, 0.8])
d = BbnNode(Variable(3, 'd', ['on', 'off']), [0.9, 0.1, 0.5, 0.5])
e = BbnNode(Variable(4, 'e', ['on', 'off']), [0.3, 0.7, 0.6, 0.4])
f = BbnNode(Variable(5, 'f', ['on', 'off']), [0.01, 0.99, 0.01, 0.99, 0.01, 0.99, 0.99, 0.01])
g = BbnNode(Variable(6, 'g', ['on', 'off']), [0.8, 0.2, 0.1, 0.9])
h = BbnNode(Variable(7, 'h', ['on', 'off']), [0.05, 0.95, 0.95, 0.05, 0.95, 0.05, 0.95, 0.05])

# create the network structure
bbn = Bbn() \
    .add_node(a) \
    .add_node(b) \
    .add_node(c) \
    .add_node(d) \
    .add_node(e) \
    .add_node(f) \
    .add_node(g) \
    .add_node(h) \
    .add_edge(Edge(a, b, EdgeType.DIRECTED)) \
    .add_edge(Edge(a, c, EdgeType.DIRECTED)) \
    .add_edge(Edge(b, d, EdgeType.DIRECTED)) \
    .add_edge(Edge(c, e, EdgeType.DIRECTED)) \
    .add_edge(Edge(d, f, EdgeType.DIRECTED)) \
    .add_edge(Edge(e, f, EdgeType.DIRECTED)) \
    .add_edge(Edge(c, g, EdgeType.DIRECTED)) \
    .add_edge(Edge(e, h, EdgeType.DIRECTED)) \
    .add_edge(Edge(g, h, EdgeType.DIRECTED))

# convert the BBN to a join tree
join_tree = InferenceController.apply(bbn)

# insert an observation evidence
ev = EvidenceBuilder() \
    .with_node(join_tree.get_bbn_node_by_name('a')) \
    .with_evidence('on', 1.0) \
    .build()
join_tree.set_observation(ev)

# print the marginal probabilities
for node in join_tree.get_bbn_nodes():
    potential = join_tree.get_bbn_potential(node)
    print(node)
    print(potential)

Building

To build, you will need 3.7. Managing environments through Anaconda is highly recommended to be able to build this project (though not absolutely required if you know what you are doing). Assuming you have installed Anaconda, you may create an environment as follows (make sure you cd into the root of this project's location).

To create the environment, use the following commands.

conda env create -f environment.yml

If you want to use the environments with Jupyter, install the kernel.

conda activate pybbn37
python -m ipykernel install --user --name pybbn37 --display-name "pybbn37"

Then you may build the project as follows. (Note that in Python 3.6 you will get some warnings).

make build

To build the documents, go into the docs sub-directory and type in the following.

make html

Publishing

To publish, make sure you have .pypirc with the correct credentials stored. Then type in the following.

./build.sh -r testpypi -v 1.0.4 # for testing
./build.sh -r pypi -v 1.0.4 # the real thing

Installing

From PyPi

Use pip to install the package as it has been published to PyPi.

pip install pybbn

From Source

If you check out the source do the following.

pip list | grep pybbn
pip uninstall pybbn
python setup.py install
pip list | grep pybbn

GraphViz issue

Make sure you install GraphViz on your system.

• CentOS: yum install graphviz*
• Ubuntu: sudo apt-get install libgraphviz-dev
• Mac OSX: brew install graphviz and when you install pygraphviz pip install pygraphviz --install-option="--include-path=/usr/local/lib/graphviz/" --install-option="--library-path=/usr/local/lib/graphviz/"
• Windows: use the msi installer
  • For Anaconda + Windows, install pygraphviz from this channel conda install -c alubbock pygraphviz

testpypi issue

You should NOT be doing this operation, but if you do want to install from testpypi, then add the --extra-index-url as follows.

pip install -i https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ pybbn

Other Python Bayesian Belief Network Inference Libraries

Here is a list of other Python libraries for inference in Bayesian Belief Networks.

Library	Algorithm	Algorithm Type	License
BayesPy	variational message passing	approximate	MIT
pomegranate	loopy belief	approximate	MIT
pgmpy	multiple	approximate/exact	MIT
libpgm	likelihood sampling	approximate	Proprietary
bayesnetinference	variable elimination	exact	None

I found other packages in PyPI too.

Java

But I am coming from the Java mothership and I want to use Bayesian Belief Networks in Java. How do I perform probabilistic inference in Java?

This Python code base is a port of the original Java code.