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)
