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julia - Julia - 在 @variable 和 @constraint 表达式中按名称访问 Dict 值

问题描述

我想知道是否可以在表达式中按名称访问 Dict 值，例如：

@objective(
    premex,
    Min,
    sum((u["cap"] - PRODAMOUNT[op, u, t]) * u["util_cost1"]
        for op in _ORDER_PRODUCTS, u in UNITS, t in TIME))

_订购_产品：

Dict{String,Dict{String,Any}}("o18-p25" => Dict("order" => "o18","value" => 3000.0f0,"product" => "p25"),"o18-p36" => Dict("order" => "o18","value" => 63.0f0,"product" => "p36"),"o23-p39" => Dict("order" => "o23","value" => 204.75f0,"product" => "p39"),"o16-p32" => Dict("order" => "o16","value" => 336.0f0,"product" => "p32"),"o22-p37" => Dict("order" => "o22","value" => 50.0f0,"product" => "p37"),"o1-p5" => Dict("order" => "o1","value" => 60.0f0,"product" => "p5"),"o11-p28" => Dict("order" => "o11","value" =....

单位：

UNITS = Dict(["CINTAS" => Dict(["cap" => 1000, "mincap" => 50, "dcap" => 24830, "util_cost1" => 1000, "maxprodr" => 24830]), "BUHLER1" => Dict(["cap" => 1500, "mincap" => 60, "dcap" => 37245, "util_cost1" => 1000, "maxprodr" => 37245]), ...

当我运行它时，我得到了一个错误：

错误：LoadError：MethodError：没有方法匹配 getindex(::Pair{String,Dict{String,Integer}}, ::String)

当我将 u["cap"] 替换为一个数字时，它会起作用。

标签： juliajulia-jump

解决方案

自己找到了答案（...）：

    @variable(premex, PRODAMOUNT[op in keys(_ORDER_PRODUCTS), u in keys(UNITS), t in TIME])

    @objective(
        premex,
        Min,
        sum((u["cap"] - PRODAMOUNT[key1, key2, t]) * u["util_cost1"]
            for (key1, op) in _ORDER_PRODUCTS, (key2, u) in UNITS, t in TIME
                ))

有3个因素需要注意：

  1. 不能用字典对象索引变量，所以它必须是 Int 或 String
  2. 这是遍历字典的方法：for (key1, op) in _ORDER_PRODUCTS
  3. 这是仅获取索引变量的键的方法： op in keys(_ORDER_PRODUCTS)

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