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我正在尝试创建一个继承另一个实例约束的实例，同时添加一些新约束。

有没有办法将前一个实例的约束“复制”到新的约束中？

这是代码中的一个片段

...
model.bnb_bound_constraints = ConstraintList()
...

non_solved_instances = []
bnb_end = False
incumbent_value = 0
solve_counter = 0
integer_variables_list = []

bnb_instance = model.create_instance(data)
variables_list = [bnb_instance.x]
non_solved_instances.append(bnb_instance) 

while bnb_end != True:

    solve_counter += 1
    print len(non_solved_instances), "Non solved instance(s)"
    bnb_solve = optsolver.solve(non_solved_instances[0], tee = False)
    print "Objective value for instance", solve_counter,":",value(non_solved_instances[0].obj)

    if value(non_solved_instances[0].obj.sense)*value(non_solved_instances[0].obj) <= value(non_solved_instances[0].obj.sense)*incumbent_value:

        incumbent_value = 2000

        for new_instance in range(2):

            bnb_instance = model.create_instance(data)
            variables_list = [bnb_instance.x]

            for con in non_solved_instances[0].bnb_bound_constraints:
                bnb_instance.bnb_bound_constraints.add(non_solved_instances[0].bnb_bound_constraints[con].expr)
                #This is what ive been trying to do to copy the constraints, doesnt work though.

            if new_instance == 0:
                bnb_instance.bnb_bound_constraints.add(expr = bnb_instance.x[solve_counter] <= floor(value(non_solved_instances[0].x[solve_counter])))
                #adds a new constraint to bnb_instance

            elif new_instance == 1:
                bnb_instance.bnb_bound_constraints.add(expr = bnb_instance.x[solve_counter] >= ceil(value(non_solved_instances[0].x[solve_counter]))) 
                #adds a new constraint to bnb_instance

            non_solved_instances.append(bnb_instance)

    del non_solved_instances[0]

    if len(non_solved_instances) == 0 or solve_counter >= 20:
        bnb_end = True

non_solved_instances[0]包含“原始”实例，我希望将其约束继承给bnb_instance

干杯!

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1 回答 1

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一种方法是克隆整个模型，然后向克隆添加额外的约束

m = ConcreteModel()
# Add stuff to m

m2 = m.clone()
m2.c2 = Constraint(expr=m2.x**2<=10)
于 2019-12-05T15:29:59.540 回答