Pyomo 变量下界

Question

大家好，我有以下问题。我有两个优化问题，第一个的输出值是第二个变量的下限。

我尝试按以下方式编写：

model_low=ConcreteModel()

#Decision Variables
model_low.p=Var((tech for tech in fuels+['hydro_big']+renew),hours,within=NonNegativeReals,initialize=2000)
model_low.C=Var(techs,within=NonNegativeReals,initialize=0)

我为下一个优化问题设置以下决策变量：

model_high=ConcreteModel()

#Decision Variables
model_high.p=Var((tech for tech in fuels+['hydro_big']+renew),hours,within=NonNegativeReals,lb=value(model_low.p),initialize=2000)
model_high.C=Var(techs,within=NonNegativeReals,lb=value(model_low.C),initialize=0)

但我收到以下错误：

ERROR: evaluating object as numeric value: p
(object: \<class 'pyomo.core.base.var.IndexedVar'\>)
'IndexedVar' object is not callable
Traceback (most recent call last):
File "C:/Final_python.py", line 144, in \<module\>
model_high.p=Var((tech for tech in fuels+\['hydro_big'\]+renew),hours,within=NonNegativeReals,lb=value(model_low.p),initialize=2000)
File "pyomo\\core\\expr\\numvalue.pyx", line 156, in pyomo.core.expr.numvalue.value
File "pyomo\\core\\expr\\numvalue.pyx", line 141, in pyomo.core.expr.numvalue.value
TypeError: 'IndexedVar' object is not callable

如何解决此问题？

Answer 1

模型中的变量似乎是索引的，因此您必须提供一些索引的下界索引工具。您可以通过（如显示）传递一个可以执行此操作的函数，就像使用规则来制定约束一样。或者，您可以将其作为模型中的约束构建，而不是在模型空间中使用下限。

我会强烈地鼓励您为您所索引的每件事制作pyomo.set，它将为您节省大量的时间故障排除等。

代码：

# 2-stage 

import pyomo.environ as pyo

m1 = pyo.ConcreteModel('stage 1')

m1.S = pyo.Set(initialize=[1, 2, 3])
m1.X = pyo.Var(m1.S, domain=pyo.NonNegativeReals)

# set some arbitrary values that would normally be done by the solver...
m1.X[1] = 4.2
m1.X[2] = 1.4
m1.X[3] = 8.0

# now lets set up the 2nd model...

m2 = pyo.ConcreteModel('stage 2')

m2.S = pyo.Set(initialize=m1.S)

# rule to initialize
def stage_2_initializer(m, s):
    return (pyo.value(m1.X[s]), None)  # (lower bound, upper bound)

m2.X = pyo.Var(m2.S, bounds=stage_2_initializer, domain=pyo.NonNegativeReals)

m2.pprint()

输出（第二阶段模型打印）：

1 Set Declarations
    S : Size=1, Index=None, Ordered=Insertion
        Key  : Dimen : Domain : Size : Members
        None :     1 :    Any :    3 : {1, 2, 3}

1 Var Declarations
    X : Size=3, Index=S
        Key : Lower : Value : Upper : Fixed : Stale : Domain
          1 :   4.2 :  None :  None : False :  True : NonNegativeReals
          2 :   1.4 :  None :  None : False :  True : NonNegativeReals
          3 :   8.0 :  None :  None : False :  True : NonNegativeReals

2 Declarations: S X
[Finished in 420ms]