79 lines
2.0 KiB
Python
79 lines
2.0 KiB
Python
# Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
"""
|
|
|
|
Volsay problem in Google or-tools.
|
|
|
|
From the OPL model volsay.mod
|
|
Using arrays.
|
|
|
|
This model was created by Hakan Kjellerstrand (hakank@gmail.com)
|
|
Also see my other Google CP Solver models:
|
|
http://www.hakank.org/google_or_tools/
|
|
"""
|
|
from __future__ import print_function
|
|
from ortools.linear_solver import pywraplp
|
|
|
|
|
|
def main(unused_argv):
|
|
|
|
# Create the solver.
|
|
|
|
# using GLPK
|
|
# solver = pywraplp.Solver('CoinsGridGLPK',
|
|
# pywraplp.Solver.GLPK_LINEAR_PROGRAMMING)
|
|
|
|
# Using CLP
|
|
solver = pywraplp.Solver('CoinsGridCLP',
|
|
pywraplp.Solver.CLP_LINEAR_PROGRAMMING)
|
|
|
|
# data
|
|
num_products = 2
|
|
Gas = 0
|
|
Chloride = 1
|
|
|
|
products = ['Gas', 'Chloride']
|
|
|
|
# declare variables
|
|
production = [
|
|
solver.NumVar(0, 100000, 'production[%i]' % i)
|
|
for i in range(num_products)
|
|
]
|
|
|
|
#
|
|
# constraints
|
|
#
|
|
solver.Add(production[Gas] + production[Chloride] <= 50)
|
|
solver.Add(3 * production[Gas] + 4 * production[Chloride] <= 180)
|
|
|
|
# objective
|
|
objective = solver.Maximize(40 * production[Gas] + 50 * production[Chloride])
|
|
|
|
print('NumConstraints:', solver.NumConstraints())
|
|
|
|
#
|
|
# solution and search
|
|
#
|
|
solver.Solve()
|
|
|
|
print()
|
|
print('objective = ', solver.Objective().Value())
|
|
for i in range(num_products):
|
|
print(products[i], '=', production[i].SolutionValue(), end=' ')
|
|
print('ReducedCost = ', production[i].ReducedCost())
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main('Volsay')
|