我对我正在尝试编写的 CPLEX 代码有一些疑问。代码本身(模型)似乎写得很好,但是在填充数据时出现错误。注意:模型中没有任何限制,因为我试图对模型进行试验只是为了看看它是否有效。
这是代码:
using CP;
// NETWORK+PARAMETERS
int trucks=...; // set of trucks
range truck= 1..trucks;
int capacity [truck]=...; // capacity of a truck
tuple nodeinfo {
string name; // name of a node
int starttime; // available start time
int endtime; // available end time
float demand; // demand from a node
}
{nodeinfo} departurenode=...; //size=4
{nodeinfo} arrivalnode=...; //size=4
{nodeinfo} startingnode=...; //size=4
// OPTION 2: vector of nodes
//each node has tuple structure nodeinfo
//length of the vector is length of dataset
//read data from dataset
//void* node = new {nodeinfo} [k];
tuple arc {
nodeinfo departurenode; //departure node of an arc
nodeinfo arrivalnode; // arrival node of an arc
nodeinfo startingnode; // starting node of an arc
int traveltime; // travel time of an arc
}
{arc} arcs=...; //number of arcs (24)
float cost [arcs][truck]; //cost of using an arc by a truck
// option2: int arc[i in departurenode,j in arrivalnode,k in startingnode]=...; //arcs (size=24)
// how can i create a setof arcs taking into account the info from each arc??
// VARIABLES
dvar boolean x [arcs,truck]; // 1 if truck uses the arc, 0 otherwise (array of size 24x7)
dvar int+ arrivaltime [arrivalnode,truck]; //arrival time of a truck at a node (array size of 4x7)
// OBJECTIVE FUNCTION
dexpr float totalcost =
sum (i in arcs, j in truck) x [i,j] * cost [i,j];
minimize totalcost;
// CONSTRAINTS
subject to {}
execute {
writeln(arcs);
};
这是数据:
trucks= 2;
departurenode= [[A,0,10000,0],[B,0,10000,0],[C,0,10000,10],[D,0,10000,10]];
arrivalnode= [[A,0,10000,0],[B,0,10000,0],[C,0,10000,10],[D,0,10000,10]];
startingnode=[[A,0,10000,0],[B,0,10000,0],[C,0,10000,10],[D,0,10000,10]];
arcs= [[<A,0,10000,0>,<A,0,10000,0>,<C,0,10000,10>,5], [<A,0,10000,0>,<A,0,10000,0>,<D,0,10000,10>,5],
[<B,0,10000,0>,<B,0,10000,0>,<C,0,10000,10>,5], [<B,0,10000,0>,<B,0,10000,0>,<D,0,10000,10>,5],
[<C,0,10000,0>,<C,0,10000,0>,<A,0,10000,10>,5], [<C,0,10000,0>,<C,0,10000,0>,<B,0,10000,10>,5],
[<D,0,10000,0>,<D,0,10000,0>,<A,0,10000,10>,5], [<D,0,10000,0>,<D,0,10000,0>,<B,0,10000,10>,5]]
cost= [<1,1>,<1,1>,<1,1>,<1,1>,<1,1>,<1,1>,<1,1>,<1,1>]
*注意:在旅行时间之前的弧的每个间隙(最后一个间隙值=5)必须是来自出发节点、到达节点和起始节点的数据,但它没有显示,我不知道为什么*
另一个疑问:关于模型的约束,我不知道如何将它们写入 CPLEX。
1)开始时间<=到达时间<=结束时间//(对于每个到达节点)
2) x * (到达时间 (节点 i) + 旅行时间) <= 到达时间 (节点 j)
3)将每辆卡车的变量到达时间初始化为0。(在模拟开始时)
4)每个到达节点的需求必须等于(选择的弧线*卡车容量)的总和
太感谢了。