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#!/usr/bin/env python3
# Copyright 2010-2025 Google LLC
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# 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.
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"""Tests for ortools.linear_solver.pywraplp."""
import unittest
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from google.protobuf import text_format
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from ortools.linear_solver import linear_solver_pb2
from ortools.linear_solver import pywraplp
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class PyWrapLpTest(unittest.TestCase):
def RunLinearExampleNaturalLanguageAPI(self, optimization_problem_type):
"""Example of simple linear program with natural language API."""
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solver = pywraplp.Solver(
"RunLinearExampleNaturalLanguageAPI", optimization_problem_type
)
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infinity = solver.infinity()
# x1, x2 and x3 are continuous non-negative variables.
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x1 = solver.NumVar(0.0, infinity, "x1")
x2 = solver.NumVar(0.0, infinity, "x2")
x3 = solver.NumVar(0.0, infinity, "x3")
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solver.Maximize(10 * x1 + 6 * x2 + 4 * x3)
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c0 = solver.Add(10 * x1 + 4 * x2 + 5 * x3 <= 600, "ConstraintName0")
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c1 = solver.Add(2 * x1 + 2 * x2 + 6 * x3 <= 300)
sum_of_vars = sum([x1, x2, x3])
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c2 = solver.Add(sum_of_vars <= 100.0, "OtherConstraintName")
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self.SolveAndPrint(
solver,
[x1, x2, x3],
[c0, c1, c2],
optimization_problem_type != pywraplp.Solver.PDLP_LINEAR_PROGRAMMING,
)
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# Print a linear expression's solution value.
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print(("Sum of vars: %s = %s" % (sum_of_vars, sum_of_vars.solution_value())))
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def RunLinearExampleCppStyleAPI(self, optimization_problem_type):
"""Example of simple linear program with the C++ style API."""
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solver = pywraplp.Solver("RunLinearExampleCppStyle", optimization_problem_type)
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infinity = solver.infinity()
# x1, x2 and x3 are continuous non-negative variables.
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x1 = solver.NumVar(0.0, infinity, "x1")
x2 = solver.NumVar(0.0, infinity, "x2")
x3 = solver.NumVar(0.0, infinity, "x3")
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# Maximize 10 * x1 + 6 * x2 + 4 * x3.
objective = solver.Objective()
objective.SetCoefficient(x1, 10)
objective.SetCoefficient(x2, 6)
objective.SetCoefficient(x3, 4)
objective.SetMaximization()
# x1 + x2 + x3 <= 100.
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c0 = solver.Constraint(-infinity, 100.0, "c0")
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c0.SetCoefficient(x1, 1)
c0.SetCoefficient(x2, 1)
c0.SetCoefficient(x3, 1)
# 10 * x1 + 4 * x2 + 5 * x3 <= 600.
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c1 = solver.Constraint(-infinity, 600.0, "c1")
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c1.SetCoefficient(x1, 10)
c1.SetCoefficient(x2, 4)
c1.SetCoefficient(x3, 5)
# 2 * x1 + 2 * x2 + 6 * x3 <= 300.
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c2 = solver.Constraint(-infinity, 300.0, "c2")
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c2.SetCoefficient(x1, 2)
c2.SetCoefficient(x2, 2)
c2.SetCoefficient(x3, 6)
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self.SolveAndPrint(
solver,
[x1, x2, x3],
[c0, c1, c2],
optimization_problem_type != pywraplp.Solver.PDLP_LINEAR_PROGRAMMING,
)
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def RunMixedIntegerExampleCppStyleAPI(self, optimization_problem_type):
"""Example of simple mixed integer program with the C++ style API."""
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solver = pywraplp.Solver(
"RunMixedIntegerExampleCppStyle", optimization_problem_type
)
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infinity = solver.infinity()
# x1 and x2 are integer non-negative variables.
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x1 = solver.IntVar(0.0, infinity, "x1")
x2 = solver.IntVar(0.0, infinity, "x2")
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# Maximize x1 + 10 * x2.
objective = solver.Objective()
objective.SetCoefficient(x1, 1)
objective.SetCoefficient(x2, 10)
objective.SetMaximization()
# x1 + 7 * x2 <= 17.5.
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c0 = solver.Constraint(-infinity, 17.5, "c0")
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c0.SetCoefficient(x1, 1)
c0.SetCoefficient(x2, 7)
# x1 <= 3.5.
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c1 = solver.Constraint(-infinity, 3.5, "c1")
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c1.SetCoefficient(x1, 1)
c1.SetCoefficient(x2, 0)
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self.SolveAndPrint(solver, [x1, x2], [c0, c1], True)
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def RunBooleanExampleCppStyleAPI(self, optimization_problem_type):
"""Example of simple boolean program with the C++ style API."""
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solver = pywraplp.Solver("RunBooleanExampleCppStyle", optimization_problem_type)
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# x1 and x2 are integer non-negative variables.
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x1 = solver.BoolVar("x1")
x2 = solver.BoolVar("x2")
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# Minimize 2 * x1 + x2.
objective = solver.Objective()
objective.SetCoefficient(x1, 2)
objective.SetCoefficient(x2, 1)
objective.SetMinimization()
# 1 <= x1 + 2 * x2 <= 3.
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c0 = solver.Constraint(1, 3, "c0")
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c0.SetCoefficient(x1, 1)
c0.SetCoefficient(x2, 2)
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self.SolveAndPrint(solver, [x1, x2], [c0], True)
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def SolveAndPrint(self, solver, variable_list, constraint_list, is_precise):
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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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self.assertEqual(solver.NumVariables(), len(variable_list))
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print(("Number of constraints = %d" % solver.NumConstraints()))
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self.assertEqual(solver.NumConstraints(), len(constraint_list))
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result_status = solver.Solve()
# The problem has an optimal solution.
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self.assertEqual(result_status, pywraplp.Solver.OPTIMAL)
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# The solution looks legit (when using solvers others than
# GLOP_LINEAR_PROGRAMMING, verifying the solution is highly recommended!).
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if is_precise:
self.assertTrue(solver.VerifySolution(1e-7, True))
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print(("Problem solved in %f milliseconds" % solver.wall_time()))
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# The objective value of the solution.
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print(("Optimal objective value = %f" % solver.Objective().Value()))
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# The value of each variable in the solution.
for variable in variable_list:
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print(("%s = %f" % (variable.name(), variable.solution_value())))
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print("Advanced usage:")
print(("Problem solved in %d iterations" % solver.iterations()))
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if not solver.IsMip():
for variable in variable_list:
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print(
(
"%s: reduced cost = %f"
% (variable.name(), variable.reduced_cost())
)
)
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activities = solver.ComputeConstraintActivities()
for i, constraint in enumerate(constraint_list):
print(
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(
"constraint %d: dual value = %f\n"
" activity = %f"
% (i, constraint.dual_value(), activities[constraint.index()])
)
)
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def testApi(self):
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print("testApi", flush=True)
all_names_and_problem_types = list(
linear_solver_pb2.MPModelRequest.SolverType.items()
)
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for name, problem_type in all_names_and_problem_types:
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with self.subTest(f"{name}: {problem_type}"):
print(f"######## {name}:{problem_type} #######", flush=True)
if not pywraplp.Solver.SupportsProblemType(problem_type):
continue
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if name.startswith("GUROBI"):
continue
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if name.startswith("KNAPSACK"):
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continue
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if not name.startswith("SCIP"):
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continue
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if name.endswith("LINEAR_PROGRAMMING"):
print(("\n------ Linear programming example with %s ------" % name))
print("\n*** Natural language API ***")
self.RunLinearExampleNaturalLanguageAPI(problem_type)
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print("\n*** C++ style API ***")
self.RunLinearExampleCppStyleAPI(problem_type)
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elif name.endswith("MIXED_INTEGER_PROGRAMMING"):
print(
(
"\n------ Mixed Integer programming example with %s ------"
% name
)
)
print("\n*** C++ style API ***")
self.RunMixedIntegerExampleCppStyleAPI(problem_type)
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elif name.endswith("INTEGER_PROGRAMMING"):
print(
("\n------ Boolean programming example with %s ------" % name)
)
print("\n*** C++ style API ***")
self.RunBooleanExampleCppStyleAPI(problem_type)
else:
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print("ERROR: %s unsupported" % name)
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def testSetHint(self):
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print("testSetHint", flush=True)
solver = pywraplp.Solver(
"RunBooleanExampleCppStyle", pywraplp.Solver.GLOP_LINEAR_PROGRAMMING
)
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infinity = solver.infinity()
# x1 and x2 are integer non-negative variables.
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x1 = solver.BoolVar("x1")
x2 = solver.BoolVar("x2")
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# Minimize 2 * x1 + x2.
objective = solver.Objective()
objective.SetCoefficient(x1, 2)
objective.SetCoefficient(x2, 1)
objective.SetMinimization()
# 1 <= x1 + 2 * x2 <= 3.
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c0 = solver.Constraint(1, 3, "c0")
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c0.SetCoefficient(x1, 1)
c0.SetCoefficient(x2, 2)
solver.SetHint([x1, x2], [1.0, 0.0])
self.assertEqual(2, len(solver.variables()))
self.assertEqual(1, len(solver.constraints()))
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def testBopInfeasible(self):
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print("testBopInfeasible", flush=True)
solver = pywraplp.Solver("test", pywraplp.Solver.BOP_INTEGER_PROGRAMMING)
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solver.EnableOutput()
x = solver.IntVar(0, 10, "")
solver.Add(x >= 20)
result_status = solver.Solve()
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print(result_status) # outputs: 0
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def testLoadSolutionFromProto(self):
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print("testLoadSolutionFromProto", flush=True)
solver = pywraplp.Solver("", pywraplp.Solver.GLOP_LINEAR_PROGRAMMING)
solver.LoadSolutionFromProto(linear_solver_pb2.MPSolutionResponse())
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def testSolveFromProto(self):
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print("testSolveFromProto", flush=True)
request_str = """
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model {
maximize: false
objective_offset: 0
variable {
lower_bound: 0
upper_bound: 4
objective_coefficient: 1
is_integer: false
name: "XONE"
}
variable {
lower_bound: -1
upper_bound: 1
objective_coefficient: 4
is_integer: false
name: "YTWO"
}
variable {
lower_bound: 0
upper_bound: inf
objective_coefficient: 9
is_integer: false
name: "ZTHREE"
}
constraint {
lower_bound: -inf
upper_bound: 5
name: "LIM1"
var_index: 0
var_index: 1
coefficient: 1
coefficient: 1
}
constraint {
lower_bound: 10
upper_bound: inf
name: "LIM2"
var_index: 0
var_index: 2
coefficient: 1
coefficient: 1
}
constraint {
lower_bound: 7
upper_bound: 7
name: "MYEQN"
var_index: 1
var_index: 2
coefficient: -1
coefficient: 1
}
name: "NAME_LONGER_THAN_8_CHARACTERS"
}
solver_type: GLOP_LINEAR_PROGRAMMING
solver_time_limit_seconds: 1.0
solver_specific_parameters: ""
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"""
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request = linear_solver_pb2.MPModelRequest()
text_format.Parse(request_str, request)
response = linear_solver_pb2.MPSolutionResponse()
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self.assertEqual(len(request.model.variable), 3)
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pywraplp.Solver.SolveWithProto(model_request=request, response=response)
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self.assertEqual(
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linear_solver_pb2.MPSolverResponseStatus.MPSOLVER_OPTIMAL, response.status
)
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def testExportToMps(self):
"""Test MPS export."""
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print("testExportToMps", flush=True)
solver = pywraplp.Solver("ExportMps", pywraplp.Solver.GLOP_LINEAR_PROGRAMMING)
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infinity = solver.infinity()
# x1, x2 and x3 are continuous non-negative variables.
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x1 = solver.NumVar(0.0, infinity, "x1")
x2 = solver.NumVar(0.0, infinity, "x2")
x3 = solver.NumVar(0.0, infinity, "x3")
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solver.Maximize(10 * x1 + 6 * x2 + 4 * x3)
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c0 = solver.Add(10 * x1 + 4 * x2 + 5 * x3 <= 600, "ConstraintName0")
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c1 = solver.Add(2 * x1 + 2 * x2 + 6 * x3 <= 300)
sum_of_vars = sum([x1, x2, x3])
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c2 = solver.Add(sum_of_vars <= 100.0, "OtherConstraintName")
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mps_str = solver.ExportModelAsMpsFormat(fixed_format=False, obfuscate=False)
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self.assertIn("ExportMps", mps_str)
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if __name__ == "__main__":
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unittest.main()