如何在 pyomo 中保存（腌制）模型实例

Question

我想创建一个模型实例，然后保存它，以便稍后加载和求解（与求解相比，初始化需要相当长的时间）。当我尝试这个时，它给了我以下错误。

with open('model.pickle', 'w') as f:
    pickle.dump(instance, f)

属性错误：无法腌制本地对象 'Euphemia.init..obj_expression

objective函数是这样的：

    def obj_expression(model):
        curve = sum(model.x[area, hour, Type, index] * model.Q[area, hour, Type, index] * 
                    ( model.P1[area, hour, Type, index] + model.P0[area, hour, Type, index] ) / 2  
                        for (area, hour, Type, index) in model.Curve )
        bids = sum(model.y[area, index] * model.PB[area, index] * 
                       sum( model.QB[area, index, hour] for (hour) in model.Hours ) 
                               for (area, index) in model.Bids  )
        return curve + bids
    self.model.OBJ = pe.Objective(rule = obj_expression, sense = pe.maximize)

有人知道如何保存具体模型吗？

Answer 1

解决办法是cloudpickle模块，普通pickle的pickle功能有问题。一个例子：

import cloudpickle

with open('test.pkl', mode='wb') as file:
   cloudpickle.dump(instance, file)


with open('test.pkl', mode='rb') as file:
   instance = cloudpickle.load(file)

Answer 2

使用 DerivativeVar 时，pickle（以及 cloudpickle）似乎不起作用。

from pyomo.environ import *
from pyomo.dae import *
import pickle
import dill
model = ConcreteModel()
model.x = ContinuousSet(initialize=(0., 1.))
model.y = Var(model.x, initialize=1.)
with open('model1.pickle', 'wb') as f:
    pickle.dump(model, f)

model.dydx = DerivativeVar(model.y, wrt=model.x)
with open('model2.pickle', 'wb') as f:
    try:
        pickle.dump(model, f)
    except TypeError:
        dill.dump(model, f)

莳萝似乎可以代替酸洗弱引用：Pickling weakref in Python

如何在 pyomo 中保存（腌制）模型实例

How to save (pickle) a model instance in pyomo

python

pyomo