stochopy

Python library for stochastic numerical optimization

https://github.com/keurfonluu/stochopy

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Python library for stochastic numerical optimization

README.rst

stochopy
========

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**stochopy** provides functions for sampling or optimizing objective functions with or without constraints. Its API is directly inspired by **scipy**'s own optimization submodule which should make the switch from one module to another straightforward.

.. figure:: https://raw.githubusercontent.com/keurfonluu/stochopy/master/.github/sample.gif
   :alt: sample-pso
   :width: 100%
   :align: center

   Optimization of 2D multimodal function Styblinski-Tang using PSO.

Features
--------

Sampling algorithms:

-  Hamiltonian (Hybrid) Monte-Carlo (HMC),
-  Markov-Chain Monte-Carlo (McMC).

Stochastic optimizers:

-  Competitive Particle Swarm Optimization (CPSO),
-  Covariance Matrix Adaptation - Evolution Strategy (CMA-ES),
-  Differential Evolution (DE),
-  Neighborhood Algorithm (NA),
-  Particle Swarm Optimization (PSO),
-  VD-CMA.

Parallel backends:

- `joblib `__ (``threading`` and ``loky``),
- `mpi4py `__ (``mpi``).

Installation
------------

The recommended way to install **stochopy** and all its dependencies is through the Python Package Index:

.. code::

   pip install stochopy --user

Otherwise, clone and extract the package, then run from the package location:

.. code::

   pip install . --user

To test the integrity of the installed package, check out this repository and run:

.. code::

   pytest

Documentation
-------------

Refer to the online `documentation `__ for detailed description of the API and examples.

Alternatively, the documentation can be built using `Sphinx `__:

.. code:: bash

   pip install -r doc/requirements.txt
   sphinx-build -b html doc/source doc/build

Usage
-----

Given an optimization problem defined by an objective function and a feasible space:

.. code-block:: python

   import numpy as np

   def rosenbrock(x):
      x = np.asarray(x)
      sum1 = ((x[1:] - x[:-1] ** 2) ** 2).sum()
      sum2 = np.square(1.0 - x[:-1]).sum()
      return 100.0 * sum1 + sum2

   bounds = [[-5.12, 5.12], [-5.12, 5.12]]  # The number of variables to optimize is len(bounds)

The optimal solution can be found following:

.. code-block:: python

   from stochopy.optimize import minimize

   x = minimize(rosenbrock, bounds, method="cmaes", options={"maxiter": 100, "popsize": 10, "seed": 0})

``minimize`` returns a dictionary that contains the results of the optimization:

.. code-block::

        fun: 3.862267657514075e-09
    message: 'best solution value is lower than ftol'
       nfev: 490
        nit: 49
     status: 1
    success: True
          x: array([0.99997096, 0.99993643])

Contributing
------------

Please refer to the `Contributing
Guidelines `__ to see how you can help. This project is released with a `Code of Conduct `__ which you agree to abide by when contributing.

Related projects
----------------

- `stochopy-viewer `__: Graphical User Interface (GUI) for **stochopy**.

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Owner

Citation (CITATION.cff)

cff-version: 1.2.0
message: "If you use this software, please cite it as below."
authors:
- family-names: "Luu"
  given-names: "Keurfon"
  orcid: "https://orcid.org/0000-0001-7927-0019"
title: "stochopy: Python library for stochastic numerical optimization"
doi: 10.5281/zenodo.4058008
url: https://github.com/keurfonluu/stochopy
license: BSD-3-Clause

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