如何使用docplex python API获取不可行约束？

w6mmgewl  于 2024-01-05  发布在  Python
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我正在研究电动汽车路径问题，我的问题的解决方案是不可行的。现在，我如何获得解决方案不可行的约束？我想使用Python API在docplex中获得违反的约束。

  1. solve_status = mdl.get_solve_status()
  2.     if solve_status.name == 'INFEASIBLE_SOLUTION':  # or also 'INFEASIBLE_OR_UNBOUNDED_SOLUTION'
  3.         cref = cr.ConflictRefiner()
  4.         print('show some of the constraints that can be removed to arrive at a minimal conflict')
  5.         cref.refine_conflict(mdl, display=True)

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我试过了，但这给了我一些违反的约束。不打印约束。

python

2条答案

按热度按时间
11dmarpk

11dmarpk1#

在docplex文档中，有一些函数可以显示冲突并在冲突上进行重命名：https://ibmdecisionoptimization.github.io/docplex-doc/mp/docplex.mp.conflict_refiner.html这些函数是docplex.mp.conflict_refiner.dislay()-显示所有冲突。docplex.mp.conflict_refiner.iter_conflicts()-返回冲突的迭代器（命名为元组）。

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0vvn1miw

0vvn1miw2#

https://github.com/AlexFleischerParis/zoodocplex/blob/master/zoorelaxationandconflict.py上的小示例

  1. from docplex.mp.model import Model
  2. from docplex.mp.relaxer import Relaxer
  4. from docplex.mp.conflict_refiner import ConflictRefiner
  6. mdl = Model(name='buses')
  7. nbbus40 = mdl.integer_var(name='nbBus40')
  8. nbbus30 = mdl.integer_var(name='nbBus30')
  10. mdl.add_constraint(nbbus40*40 + nbbus30*30 >= 300, 'kids')
  11. mdl.add_constraint(nbbus40 + nbbus30 <= 7, 'maxTotalBuses')
  13. mdl.minimize(nbbus40*500 + nbbus30*400)
  15. mdl.solve()
  17. mdl.report()
  18. print(f"* solve status is: '{mdl.solve_details.status}'") #infeasible model
  20. print()
  21. print("------- starting relaxation")
  22. print()
  24. rx = Relaxer()
  25. rx.relax(mdl)
  27. print ("number_of_relaxations= " + str(rx.number_of_relaxations))
  28. rx.print_information()
  30. mdl.report()
  31. print(f"* status after relaxation is: {mdl.solve_details.status}")
  32. #print(mdl.solution)
  34. print()
  35. print("------ starting conflict refiner")
  36. print()
  38. cr=ConflictRefiner()
  39. conflicts=cr.refine_conflict(mdl)
  40. conflicts.display()
  42. # for conflict in conflicts:
  43. #     st = conflict.status
  44. #     ct = conflict.element
  45. #     label = conflict.name
  46. #     label_type = type(conflict.element)
  47. #     if isinstance(conflict.element, VarLbConstraintWrapper) \
  48. #             or isinstance(conflict.element, VarUbConstraintWrapper):
  49. #         ct = conflict.element.get_constraint()
  50. #
  51. #     # Print conflict information in console
  52. #     print("Conflict involving constraint: %s" % label)
  53. #     print(" \tfor: %s" % ct)
  55. """
  57. which gives
  59. * solve status is: 'integer infeasible'
  61. ------- starting relaxation
  63. number_of_relaxations= 1
  64. * number of relaxations: 1
  65.  - relaxed: maxTotalBuses, with relaxation: 1.0
  66. * total absolute relaxation: 1.0
  67. * model buses solved with objective = 3800
  68. * status after relaxation is: optimal relaxed sum of infeasibilities
  70. ------ starting conflict refiner
  72. conflict(s): 3
  73.   - status: Member, Variable Lower Bound: nbBus30 >= 0
  74.   - status: Member, LinearConstraint: kids: 40nbBus40+30nbBus30 >= 300
  75.   - status: Member, LinearConstraint: maxTotalBuses: nbBus40+nbBus30 <= 7
  77.   """

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