src/LinearProgramming.py

   1 """
   2 Classes to create, solve, and make dinner for linear programs. Handles
   3 integration with lp_solve.
   4 """
   5
   6 import os
   7 import site
   8 import sys
   9
  10 # Add LP_SOLVE_PATH to our path. There is no point to this variable
  11 # other than to make the site.addsitedir() line fit within 80
  12 # characters.
  13 LP_SOLVE_PATH = '/../lib/lp_solve'
  14 site.addsitedir(os.path.dirname(os.path.abspath(sys.argv[0])) + LP_SOLVE_PATH)
  15
  16 from lp_solve import *
  17
  18
  19 # Constants denoting the three different types of (in)equalities.
  20 # These are defined by lp_solve.
  21 LEQ = -1 # Less than or equal to.
  22 EQ  =  0 # Equal to
  23 GEQ =  1 # Greater than or Equal to.
  24
  25
  26 class LinearProgram(object):
  27     """
  28     Represents an instance of an lp_solve linear program.
  29     """
  30
  31     def __init__(self):
  32         self.objective_function_coefficients = []
  33         self.constraint_matrix = []
  34         self.rhs = []
  35         self.inequalities = []
  36
  37
  38     def solve(self):
  39         [v,x,duals] = lp_solve(self.objective_function_coefficients,
  40                                self.constraint_matrix,
  41                                self.rhs,
  42                                self.inequalities)
  43         return [v,x,duals]
  44