rmateus / pulp

A python Linear Programming API

#pulp

PuLP is an LP modeler written in python. PuLP can generate MPS or LP files and call GLPK[1], COIN CLP/CBC[2], CPLEX[3], and GUROBI[4] to solve linear problems.

##Installation

The easiest way to install pulp is via PyPi

If pip is available on your system

 $pip install pulp

Otherwise follow the download instructions on the PyPi page On Linux and OSX systems the tests must be run to make the default solver executable.

 $sudo pulptest

##Examples

See the examples directory for examples.

PuLP requires Python >= 2.6.

The examples use the default solver (cbc), to use other solvers they must be available.

#Documentation Documentation is found on https://pythonhosted.org/PuLP/.

Use LpVariable() to create new variables. To create a variable 0 <= x <= 3

 >>> x = LpVariable("x", 0, 3)

To create a variable 0 <= y <= 1

 >>> y = LpVariable("y", 0, 1)

Use LpProblem() to create new problems. Create "myProblem"

 >>> prob = LpProblem("myProblem", LpMinimize)

Combine variables to create expressions and constraints and add them to the problem.

 >>> prob += x + y <= 2

If you add an expression (not a constraint), it will become the objective.

 >>> prob += -4*x + y

To solve with the default included solver

 >>> status = prob.solve()

To use another sovler 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

Exported Classes:

• LpProblem -- Container class for a Linear programming problem

• LpVariable -- Variables that are added to constraints in the LP

• LpConstraint -- A constraint of the general form

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

• LpConstraintVar -- Used to construct a column of the model in column-wise modelling

Exported Functions:

• value() -- Finds the value of a variable or expression
• lpSum() -- given a list of the form [a1*x1, a2x2, ..., anxn] 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 epression to be used as a constraint or variable

Comments, bug reports, patches and suggestions are welcome. [e-mail]

 Copyright J.S. Roy ([e-mail]), 2003-2005
 Copyright Stuart A. Mitchell ([e-mail])
 See the LICENSE file for copyright information.

References: [1] http://www.gnu.org/software/glpk/glpk.html [2] http://www.coin-or.org/ [3] http://www.cplex.com/ [4] http://www.gurobi.com/