pulp

pulp

.. image:: https://travis-ci.org/coin-or/pulp.svg?branch=master :target: https://travis-ci.org/coin-or/pulp .. image:: https://img.shields.io/pypi/v/pulp :target: https://pypi.org/project/PuLP/ :alt: PyPI .. image:: https://img.shields.io/pypi/dm/pulp :target: https://pypi.org/project/PuLP/ :alt: PyPI - Downloads

PuLP is an linear and mixed integer programming modeler written in Python. With PuLP, it is simple to create MILP optimisation problems and solve them with the latest open-source (or proprietary) solvers. PuLP can generate MPS or LP files and call solvers such as GLPK_, COIN-OR CLP/CBC, CPLEX, GUROBI_, MOSEK_, XPRESS_, CHOCO_, MIPCL_, HiGHS_, SCIP_/FSCIP_.

The documentation for PuLP can be found here <https://coin-or.github.io/pulp/>_.

PuLP is part of the COIN-OR project <https://www.coin-or.org/>_.

Installation

PuLP requires Python 3.10 or newer.

The easiest way to install PuLP is with pip. If pip is available on your system, type::

 python -m pip install pulp

Otherwise follow the download instructions on the PyPi page <https://pypi.python.org/pypi/PuLP>_.

Installing solvers

PuLP can use a variety of solvers. The default solver is the COIN-OR CBC solver via the COIN_CMD API. Install CBC with::

python -m pip install pulp[cbc]

If CBC is not available on your system, PuLP falls back to other solvers such as the legacy bundled CBC (PULP_CBC_CMD) or GLPK.

To install other solvers, PuLP offers a quick way to install most solvers via their pypi package (some require a commercial license for running or for running large models)::

python -m pip install pulp[cbc]
python -m pip install pulp[gurobi]
python -m pip install pulp[cplex]
python -m pip install pulp[xpress]
python -m pip install pulp[scip]
python -m pip install pulp[highs]
python -m pip install pulp[copt]
python -m pip install pulp[mosek]

If you want to install all open source solvers (scip, highs, cylp), you can use the shortcut:: python -m pip install pulp[open_py]

For more information on how to install solvers, see the guide on configuring solvers <https://coin-or.github.io/pulp/guides/how_to_configure_solvers.html>_.

Quickstart

Create a problem first, then add variables with add_variable (variables are owned by the model). To create a variable x with 0 ≤ x ≤ 3 and a binary variable y::

 from pulp import *
 prob = LpProblem("myProblem", LpMinimize)
 x = prob.add_variable("x", 0, 3)
 y = prob.add_variable("y", cat="Binary")

Combine variables in order to create expressions and constraints, and then add them to the problem.::

 prob += x + y <= 2

An expression is a constraint without a right-hand side (RHS) sense (one of =, <= or >=). If you add an expression to a problem, it will become the objective::

 prob += -4*x + y

To solve the problem with the default solver (CBC via COIN_CMD when installed with pulp[cbc])::

 status = prob.solve()

To solve explicitly with CBC::

 status = prob.solve(COIN_CMD(msg=0))

If you want to try another solver to solve the problem::

 status = prob.solve(GLPK(msg = 0))

Display the status of the solution::

 LpStatus[status]
 > 'Optimal'

You can get the value of the variables using value. ex::

 value(x)
 > 2.0

Essential Classes

• LpProblem -- Container class for a Linear or Integer programming problem

• LpVariable -- Variables that are added into constraints in the LP problem

• LpConstraint -- Constraints of the general form

  a1x1 + a2x2 + ... + anxn (<=, =, >=) b
  

• LpConstraintVar -- A special type of constraint for constructing column of the model in column-wise modelling

Useful Functions

• value() -- Finds the value of a variable or expression
• lpSum() -- Given a list of the form [a1x1, a2x2, ..., an*xn] will construct a linear expression to be used as a constraint or variable
• lpDot() -- Given two lists of the form [a1, a2, ..., an] and [x1, x2, ..., xn] will construct a linear expression to be used as a constraint or variable

More Examples

Several tutorial are given in documentation <https://coin-or.github.io/pulp/CaseStudies/index.html>_ and pure code examples are available in examples/ directory <https://github.com/coin-or/pulp/tree/master/examples>_ .

The examples use the default solver (CBC via COIN_CMD when available). To use other solvers they must be available (installed and accessible). For more information on how to do that, see the guide on configuring solvers <https://coin-or.github.io/pulp/guides/how_to_configure_solvers.html>_.

For Developers

If you want to install the latest version from GitHub you can run::

python -m pip install -U git+https://github.com/coin-or/pulp

Building the documentation

The PuLP documentation is built with Sphinx <https://www.sphinx-doc.org>. We recommended using a virtual environment <https://docs.python.org/3/library/venv.html> to build the documentation locally.

To build, run the following in a terminal window, in the PuLP root directory

::

python3 -m pip install --upgrade pip
pip install --group=dev .
cd doc
make html

A folder named html will be created inside the build/ directory. The home page for the documentation is doc/build/html/index.html which can be opened in a browser.

Contributing to PuLP

Instructions for making your first contribution to PuLP are given here <https://coin-or.github.io/pulp/develop/contribute.html>_.

Comments, bug reports, patches and suggestions are very welcome!

• Comments and suggestions: https://github.com/coin-or/pulp/discussions
• Bug reports: https://github.com/coin-or/pulp/issues
• Patches: https://github.com/coin-or/pulp/pulls

Copyright and License

PuLP is distributed under an MIT license.

 Copyright J.S. Roy, 2003-2005
 Copyright Stuart A. Mitchell
 See the LICENSE file for copyright information.

.. _Python: http://www.python.org/

.. _GLPK: http://www.gnu.org/software/glpk/glpk.html .. _CBC: https://github.com/coin-or/Cbc .. _CPLEX: http://www.cplex.com/ .. _GUROBI: http://www.gurobi.com/ .. _MOSEK: https://www.mosek.com/ .. _XPRESS: https://www.fico.com/es/products/fico-xpress-solver .. _CHOCO: https://choco-solver.org/ .. _MIPCL: http://mipcl-cpp.appspot.com/ .. _SCIP: https://www.scipopt.org/ .. _HiGHS: https://highs.dev .. _FSCIP: https://ug.zib.de