[英]Get an instance to inherit another instance's constraints in pyomo
I'm trying to create an instance that inherits another instance's constraints, whilst adding some new ones.我正在尝试创建一个继承另一个实例约束的实例,同时添加一些新的约束。
Is there a way to "copy" the previous instance's constraints into the new one?有没有办法将前一个实例的约束“复制”到新实例中?
Here's a snippet from the code这是代码的一个片段
...
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] contains the "original" instance, whose constraints i wish to inherit to bnb_instance non_solved_instances[0]包含“原始”实例,我希望将其约束继承到bnb_instance
Cheers!干杯!
One way would be to clone the entire model and then add additional constraints to the clone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)
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