122 lines
4.1 KiB
Python
122 lines
4.1 KiB
Python
# Copyright 2010-2013 Google
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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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"""Integer programming examples that show how to use the APIs."""
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from google.apputils import app
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from ortools.linear_solver import pywraplp
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def RunIntegerExampleNaturalLanguageAPI(optimization_problem_type):
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"""Example of simple integer program with natural language API."""
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solver = pywraplp.Solver('RunIntegerExampleNaturalLanguageAPI',
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optimization_problem_type)
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infinity = solver.Infinity()
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# x1 and x2 are integer non-negative variables.
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x1 = solver.IntVar(0.0, infinity, 'x1')
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x2 = solver.IntVar(0.0, infinity, 'x2')
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solver.Minimize(x1 + 2 * x2)
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solver.Add(3 * x1 + 2 * x2 >= 17)
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SolveAndPrint(solver, [x1, x2])
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def RunIntegerExampleCppStyleAPI(optimization_problem_type):
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"""Example of simple integer program with the C++ style API."""
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solver = pywraplp.Solver('RunIntegerExampleCppStyleAPI',
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optimization_problem_type)
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infinity = solver.Infinity()
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# x1 and x2 are integer non-negative variables.
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x1 = solver.IntVar(0.0, infinity, 'x1')
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x2 = solver.IntVar(0.0, infinity, 'x2')
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# Minimize x1 + 2 * x2.
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solver.SetObjectiveCoefficient(x1, 1)
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solver.SetObjectiveCoefficient(x2, 2)
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# 2 * x2 + 3 * x1 >= 17.
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ct = solver.Constraint(17, infinity)
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ct.SetCoefficient(x1, 3)
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ct.SetCoefficient(x2, 2)
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SolveAndPrint(solver, [x1, x2])
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def SolveAndPrint(solver, variable_list):
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"""Solve the problem and print the solution."""
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print('Number of variables = %d' % solver.NumVariables())
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print('Number of constraints = %d' % solver.NumConstraints())
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result_status = solver.Solve()
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# The problem has an optimal solution.
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assert result_status == pywraplp.Solver.OPTIMAL
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print('Problem solved in %f milliseconds' % solver.WallTime())
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# The objective value of the solution.
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print('Optimal objective value = %f' % solver.ObjectiveValue())
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# The value of each variable in the solution.
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for variable in variable_list:
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print('%s = %f' % (variable.name(), variable.SolutionValue()))
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print('Advanced usage:')
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print('Problem solved in %d branch-and-bound nodes' % solver.Nodes())
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def Announce(solver, api_type):
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print(('---- Integer programming example with ' + solver + ' (' +
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api_type + ') -----'))
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def RunAllIntegerExampleNaturalLanguageAPI():
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if hasattr(pywraplp.Solver, 'GLPK_MIXED_INTEGER_PROGRAMMING'):
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Announce('GLPK', 'natural language API')
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RunIntegerExampleNaturalLanguageAPI(
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pywraplp.Solver.GLPK_MIXED_INTEGER_PROGRAMMING)
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if hasattr(pywraplp.Solver, 'CBC_MIXED_INTEGER_PROGRAMMING'):
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Announce('CBC', 'natural language API')
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RunIntegerExampleNaturalLanguageAPI(
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pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
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if hasattr(pywraplp.Solver, 'SCIP_MIXED_INTEGER_PROGRAMMING'):
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Announce('SCIP', 'natural language API')
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RunIntegerExampleNaturalLanguageAPI(
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pywraplp.Solver.SCIP_MIXED_INTEGER_PROGRAMMING)
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def RunAllIntegerExampleCppStyleAPI():
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if hasattr(pywraplp.Solver, 'GLPK_MIXED_INTEGER_PROGRAMMING'):
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Announce('GLPK', 'C++ style API')
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RunIntegerExampleCppStyleAPI(pywraplp.Solver.GLPK_MIXED_INTEGER_PROGRAMMING)
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if hasattr(pywraplp.Solver, 'CBC_MIXED_INTEGER_PROGRAMMING'):
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Announce('CBC', 'C++ style API')
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RunIntegerExampleCppStyleAPI(pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
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if hasattr(pywraplp.Solver, 'SCIP_MIXED_INTEGER_PROGRAMMING'):
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Announce('SCIP', 'C++ style API')
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RunIntegerExampleCppStyleAPI(
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pywraplp.Solver.SCIP_MIXED_INTEGER_PROGRAMMING)
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def main(unused_argv):
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RunAllIntegerExampleNaturalLanguageAPI()
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RunAllIntegerExampleCppStyleAPI()
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if __name__ == '__main__':
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app.run()
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