152 lines
3.6 KiB
Python
152 lines
3.6 KiB
Python
# Copyright 2011 Hakan Kjellerstrand hakank@bonetmail.com
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Blending problem in Google or-tools.
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From the OPL model blending.mod.
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This model was created by Hakan Kjellerstrand (hakank@bonetmail.com)
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Also see my other Google CP Solver models: http://www.hakank.org/google_or_tools/
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"""
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import sys
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from ortools.linear_solver import pywraplp
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def main(sol = 'GLPK'):
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# Create the solver.
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print 'Solver: ', sol
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# using GLPK
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if sol == 'GLPK':
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solver = pywraplp.Solver('CoinsGridGLPK',
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pywraplp.Solver.GLPK_MIXED_INTEGER_PROGRAMMING)
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else:
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# Using CLP
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solver = pywraplp.Solver('CoinsGridCLP',
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pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
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#
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# data
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#
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NbMetals = 3
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NbRaw = 2
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NbScrap = 2
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NbIngo = 1
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Metals = range(NbMetals)
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Raws = range(NbRaw)
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Scraps = range(NbScrap)
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Ingos = range(NbIngo)
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CostMetal = [22, 10, 13]
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CostRaw = [6, 5]
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CostScrap = [ 7, 8]
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CostIngo = [9 ]
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Low = [0.05, 0.30, 0.60]
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Up = [0.10, 0.40, 0.80]
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PercRaw = [ [ 0.20, 0.01 ], [ 0.05, 0 ], [ 0.05, 0.30 ] ]
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PercScrap = [ [ 0 , 0.01 ], [ 0.60, 0 ], [ 0.40, 0.70 ] ]
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PercIngo = [ [ 0.10 ], [ 0.45 ], [ 0.45 ] ]
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Alloy = 71
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#
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# variables
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#
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p = [solver.NumVar(0, solver.Infinity(), 'p[%i]' % i) for i in Metals]
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r = [solver.NumVar(0, solver.Infinity(), 'r[%i]' % i) for i in Raws]
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s = [solver.NumVar(0, solver.Infinity(), 's[%i]' % i) for i in Scraps]
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ii = [solver.IntVar(0, solver.Infinity(), 'ii[%i]' % i) for i in Ingos]
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metal = [solver.NumVar(Low[j]*Alloy, Up[j]*Alloy, 'metal[%i]' % j)
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for j in Metals]
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z = solver.NumVar(0, solver.Infinity(), 'z')
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#
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# constraints
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#
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solver.Add(z ==
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solver.Sum([CostMetal[i] * p[i] for i in Metals]) +
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solver.Sum([CostRaw[i] * r[i] for i in Raws]) +
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solver.Sum([CostScrap[i] * s[i] for i in Scraps]) +
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solver.Sum([CostIngo[i] * ii[i] for i in Ingos]))
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for j in Metals:
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solver.Add(
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metal[j] == p[j] +
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solver.Sum([PercRaw[j][k] * r[k] for k in Raws]) +
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solver.Sum([PercScrap[j][k] * s[k] for k in Scraps]) +
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solver.Sum([PercIngo[j][k] * ii[k] for k in Ingos]))
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solver.Add(solver.Sum(metal) == Alloy)
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objective = solver.Minimize(z)
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#
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# solution and search
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#
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solver.Solve()
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print
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print 'z = ', solver.ObjectiveValue()
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print 'Metals'
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for i in Metals:
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print p[i].SolutionValue(),
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print
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print 'Raws'
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for i in Raws:
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print r[i].SolutionValue(),
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print
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print 'Scraps'
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for i in Scraps:
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print s[i].SolutionValue(),
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print
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print 'Ingos'
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for i in Ingos:
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print ii[i].SolutionValue(),
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print
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print 'Metals'
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for i in Metals:
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print metal[i].SolutionValue(),
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print
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print
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print 'walltime :', solver.WallTime(), 'ms'
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if sol == 'CBC':
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print 'iterations:', solver.Iterations()
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if __name__ == '__main__':
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sol = 'GLPK'
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if len(sys.argv) > 1:
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sol = sys.argv[1]
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if sol != 'GLPK' and sol != 'CBC':
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print 'Solver must be either GLPK or CBC'
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sys.exit(1)
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main(sol)
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