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lp.py
#!/usr/bin/env python3.7
# Copyright 2023, Gurobi Optimization, LLC
# This example reads an LP model from a file and solves it.
# If the model is infeasible or unbounded, the example turns off
# presolve and solves the model again. If the model is infeasible,
# the example computes an Irreducible Inconsistent Subsystem (IIS),
# and writes it to a file
import sys
import gurobipy as gp
from gurobipy import GRB
if len(sys.argv) < 2:
print('Usage: lp.py filename')
sys.exit(0)
# Read and solve model
model = gp.read(sys.argv[1])
model.optimize()
if model.Status == GRB.INF_OR_UNBD:
# Turn presolve off to determine whether model is infeasible
# or unbounded
model.setParam(GRB.Param.Presolve, 0)
model.optimize()
if model.Status == GRB.OPTIMAL:
print('Optimal objective: %g' % model.ObjVal)
model.write('model.sol')
sys.exit(0)
elif model.Status != GRB.INFEASIBLE:
print('Optimization was stopped with status %d' % model.Status)
sys.exit(0)
# Model is infeasible - compute an Irreducible Inconsistent Subsystem (IIS)
print('')
print('Model is infeasible')
model.computeIIS()
model.write("model.ilp")
print("IIS written to file 'model.ilp'")
