PyMC3 is a Python package for Bayesian statistical modeling and Probabilistic Machine Learning focusing on advanced Markov chain Monte Carlo (MCMC) and variational inference (VI) algorithms. Its flexibility and extensibility make it applicable to a large suite of problems.

Check out the getting started guide, or interact with live examples using Binder! For questions on PyMC3, head on over to our PyMC Discourse forum.

Features

• Intuitive model specification syntax, for example, x ~ N(0,1) translates to x = Normal('x',0,1)
• Powerful sampling algorithms, such as the No U-Turn Sampler, allow complex models with thousands of parameters with little specialized knowledge of fitting algorithms.
• Variational inference: ADVI for fast approximate posterior estimation as well as mini-batch ADVI for large data sets.

• Relies on Aesara which provides:

  • Computation optimization and dynamic C or JAX compilation
  • Numpy broadcasting and advanced indexing
  • Linear algebra operators
  • Simple extensibility

• Transparent support for missing value imputation

Getting started

If you already know about Bayesian statistics:

• API quickstart guide
• The PyMC3 tutorial
• PyMC3 examples and the API reference

Learn Bayesian statistics with a book together with PyMC3:

• Probabilistic Programming and Bayesian Methods for Hackers: Fantastic book with many applied code examples.
• PyMC3 port of the book "Doing Bayesian Data Analysis" by John Kruschke as well as the second edition: Principled introduction to Bayesian data analysis.
• PyMC3 port of the book "Statistical Rethinking A Bayesian Course with Examples in R and Stan" by Richard McElreath
• PyMC3 port of the book "Bayesian Cognitive Modeling" by Michael Lee and EJ Wagenmakers: Focused on using Bayesian statistics in cognitive modeling.
• Bayesian Analysis with Python (second edition) by Osvaldo Martin: Great introductory book. (code and errata).

PyMC3 talks

There are also several talks on PyMC3 which are gathered in this YouTube playlist and as part of PyMCon 2020

Installation

To install PyMC3 on your system, follow the instructions on the appropriate installation guide:

• Installing PyMC3 on MacOS
• Installing PyMC3 on Linux
• Installing PyMC3 on Windows

Citing PyMC3

Please choose from the following:

• Probabilistic programming in Python using PyMC3, Salvatier J., Wiecki T.V., Fonnesbeck C. (2016)
• A DOI for all versions.
• DOIs for specific versions are shown on Zenodo and under Releases

Contact

We are using discourse.pymc.io as our main communication channel. You can also follow us on Twitter @pymc_devs for updates and other announcements.

To ask a question regarding modeling or usage of PyMC3 we encourage posting to our Discourse forum under the “Questions” Category. You can also suggest feature in the “Development” Category.

To report an issue with PyMC3 please use the issue tracker.

Finally, if you need to get in touch for non-technical information about the project, send us an e-mail.

License

Apache License, Version 2.0

Software using PyMC3

• Exoplanet: a toolkit for modeling of transit and/or radial velocity observations of exoplanets and other astronomical time series.
• Bambi: BAyesian Model-Building Interface (BAMBI) in Python.
• pymc3_models: Custom PyMC3 models built on top of the scikit-learn API.
• PMProphet: PyMC3 port of Facebook's Prophet model for timeseries modeling
• webmc3: A web interface for exploring PyMC3 traces
• sampled: Decorator for PyMC3 models.
• NiPyMC: Bayesian mixed-effects modeling of fMRI data in Python.
• beat: Bayesian Earthquake Analysis Tool.
• pymc-learn: Custom PyMC models built on top of pymc3_models/scikit-learn API
• fenics-pymc3: Differentiable interface to FEniCS, a library for solving partial differential equations.
• cell2location: Comprehensive mapping of tissue cell architecture via integrated single cell and spatial transcriptomics.

Please contact us if your software is not listed here.

Papers citing PyMC3

See Google Scholar for a continuously updated list.

Contributors

See the GitHub contributor page. Also read our Code of Conduct guidelines for a better contributing experience.

Support

PyMC3 is a non-profit project under NumFOCUS umbrella. If you want to support PyMC3 financially, you can donate here.

PyMC for enterprise

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