Hello,

Please help me with the following issue.

I have the following tuples:

int NumNodes = 5; // Number of nodes
range Nodes = 1..NumNodes;

int Tmax = 5; // Number of periods 
range T = 1..Tmax;

tuple TimeNode { //Defining a node replicated in time
key int node;
key int time;
}
{TimeNode} tnodes = { <n,t> | n in Nodes, t in T };

tuple Arcs{ /
key TimeNode FromNode; //node i
key TimeNode ToNode;      // node j
}

{Arcs} arcs ={<<1,1>,<5,2>>,<<1,2>,<5,3>>,<<1,3>,<5,4>>,<<1,4>,<5,5>>.......};

My question is, how do I change tuple elements' position in a tuple, so that in output it gives:
 <<5,2>,<1,1>>,<<5,3>,<1,2>>,<<5,4>,<1,3>>,<<5,5>,<1,4>> basically, so that the tuples within the tuple {Arcs} change their posiiton. 

Thank you in advance for any support.
BR, Irina

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Irina Tremaskina
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#DecisionOptimization

I am not sure why you cannot just swap the lines in the tuple definition:
tuple Arcs{
  key TimeNode ToNode; // node j
  key TimeNode FromNode; //node i
}
?
If the lines cannot be swapped, then there are several options:
If you have control of the output then instead of outputting an arc 'a' you can output '<arg.ToNode, arg.FromNode>'.
Another option is to create an "inverse tuple":
tuple InverseArc {
  key TimeNode ToNode;
  key TimeNode FromNode;
};
and then create a corresponding set of inverse arcs:
{InverseArc} inverse_arc_set = { <t.ToNode, t.FromNode | t in arcs };
InverseArc inverse_arc_array[t in arcs] = < t.ToNode, t.FromNode >;

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Daniel Junglas
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