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.
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
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 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, then 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. [email protected]
Copyright J.S. Roy ([email protected]), 2003-2005
Copyright Stuart A. Mitchell ([email protected])
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/