pyomo：如何僅在集合的一部分中索引變量？

Andre 发表于 Dev

第二

我正在嘗試在pyomo優化模型中跟踪 SOC 。我有許多 BEV，我想跟踪每個 SOC。我傳遞給的 xpressionpe.Objective如下所示：

sum(sum(model.SOC[t+1, b] - model.SOC[t, b] for b in model.buses) for t in model.times)

model.buses並且model.times是我已經聲明為的兩個集合pe.Set。時間從 (0, ...., 95) 開始。因此，在最後一次迭代中，model.times它嘗試訪問model.SOC[96, b]導致KeyError.

有沒有辦法告訴 pyomo 離開集合的最後一個元素來防止這個錯誤？

類似於：

sum(sum(model.SOC[t+1, b] - model.SOC[t, b] for b in model.buses) for t in model.times[0:-2])

可悲的是，這也引發了一個錯誤：

IndexError: times indices must be integers, not slice

這是一個應該重現錯誤的最小示例：

import pyomo.environ as pe

solver = pe.SolverFactory('glpk')
model = pe.ConcreteModel('Test')
model.times = pe.Set(initialize=list(range(96)))
model.buses = pe.Set(initialize=list(range(5)))
model.SOC = pe.Var(model.times*model.buses, domain=pe.PositiveReals)

def example_rule(model):
    return sum(sum(model.SOC[t+1, b] - model.SOC[t, b] for b in model.buses) for t in model.times)

model.obj = pe.Objective(rule=example_rule, sense=pe.maximize)

model.pprint()

提前謝謝了！

魷魚

是的，有幾種方法可以做到這一點。首先，如果你想索引是有序的（這是默認值）的設置，您可以使用first，last以及prev以各種方式設置的方法。（請參閱我對下面代碼的編輯）

其次，您始終可以構建自己的子集並將其放入或不放入模型中。下面的第二個模型顯示了任意複雜子集的構造並將其放入模型中。該集合可用作目標或約束的基礎。

此解決方案類似於此答案

import pyomo.environ as pe

solver = pe.SolverFactory('glpk')
model = pe.ConcreteModel('Test')
model.times = pe.Set(initialize=list(range(5)), ordered=True)  # ordered is default, this is for clarity...
model.buses = pe.Set(initialize=list(range(2)))
model.SOC = pe.Var(model.times*model.buses, domain=pe.PositiveReals)

def example_rule(model):
    return sum(sum(model.SOC[t+1, b] - model.SOC[t, b] for b in model.buses) for t in model.times if t != model.times.last())

model.obj = pe.Objective(rule=example_rule, sense=pe.maximize)

model.pprint()


# making your own subset...
times = 10
model2 = pe.ConcreteModel("other")
model2.times = pe.Set(initialize=range(times))
# make a subset of the even values that are no more than 4 values close to the end....
model2.times_subset = pe.Set(initialize=[t for t in model2.times if t%2==0 and t <= times-4])

model2.pprint()

產量：

3 Set Declarations
    SOC_index : Size=1, Index=None, Ordered=True
        Key  : Dimen : Domain      : Size : Members
        None :     2 : times*buses :   10 : {(0, 0), (0, 1), (1, 0), (1, 1), (2, 0), (2, 1), (3, 0), (3, 1), (4, 0), (4, 1)}
    buses : Size=1, Index=None, Ordered=Insertion
        Key  : Dimen : Domain : Size : Members
        None :     1 :    Any :    2 : {0, 1}
    times : Size=1, Index=None, Ordered=Insertion
        Key  : Dimen : Domain : Size : Members
        None :     1 :    Any :    5 : {0, 1, 2, 3, 4}

1 Var Declarations
    SOC : Size=10, Index=SOC_index
        Key    : Lower : Value : Upper : Fixed : Stale : Domain
        (0, 0) :     0 :  None :  None : False :  True : PositiveReals
        (0, 1) :     0 :  None :  None : False :  True : PositiveReals
        (1, 0) :     0 :  None :  None : False :  True : PositiveReals
        (1, 1) :     0 :  None :  None : False :  True : PositiveReals
        (2, 0) :     0 :  None :  None : False :  True : PositiveReals
        (2, 1) :     0 :  None :  None : False :  True : PositiveReals
        (3, 0) :     0 :  None :  None : False :  True : PositiveReals
        (3, 1) :     0 :  None :  None : False :  True : PositiveReals
        (4, 0) :     0 :  None :  None : False :  True : PositiveReals
        (4, 1) :     0 :  None :  None : False :  True : PositiveReals

1 Objective Declarations
    obj : Size=1, Index=None, Active=True
        Key  : Active : Sense    : Expression
        None :   True : maximize : SOC[1,0] - SOC[0,0] + SOC[1,1] - SOC[0,1] + SOC[2,0] - SOC[1,0] + SOC[2,1] - SOC[1,1] + SOC[3,0] - SOC[2,0] + SOC[3,1] - SOC[2,1] + SOC[4,0] - SOC[3,0] + SOC[4,1] - SOC[3,1]

5 Declarations: times buses SOC_index SOC obj
2 Set Declarations
    times : Size=1, Index=None, Ordered=Insertion
        Key  : Dimen : Domain : Size : Members
        None :     1 :    Any :   10 : {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
    times_subset : Size=1, Index=None, Ordered=Insertion
        Key  : Dimen : Domain : Size : Members
        None :     1 :    Any :    4 : {0, 2, 4, 6}

2 Declarations: times times_subset
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