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params.py
#!/usr/bin/env python3.7
# Copyright 2023, Gurobi Optimization, LLC
# Use parameters that are associated with a model.
#
# A MIP is solved for a few seconds with different sets of parameters.
# The one with the smallest MIP gap is selected, and the optimization
# is resumed until the optimal solution is found.
import sys
import gurobipy as gp
if len(sys.argv) < 2:
print('Usage: params.py filename')
sys.exit(0)
# Read model and verify that it is a MIP
m = gp.read(sys.argv[1])
if m.IsMIP == 0:
print('The model is not an integer program')
sys.exit(1)
# Set a 2 second time limit
m.Params.TimeLimit = 2
# Now solve the model with different values of MIPFocus
bestModel = m.copy()
bestModel.optimize()
for i in range(1, 4):
m.reset()
m.Params.MIPFocus = i
m.optimize()
if bestModel.MIPGap > m.MIPGap:
bestModel, m = m, bestModel # swap models
# Finally, delete the extra model, reset the time limit and
# continue to solve the best model to optimality
del m
bestModel.Params.TimeLimit = float('inf')
bestModel.optimize()
print('Solved with MIPFocus: %d' % bestModel.Params.MIPFocus)
