Originally posted by: naveendivakaran

Hi,

 

I have been trying to name a subset of constraints in my LP, with tuples. Unfortunately, when I look at the generated LP, the constraint names do not reflect the strings in the tuple. Am I doing something wrong? Can someone help me with this?

 

Snippets from mod file

//Tuple Definition

tuple t3s5i2f {string str1; string str2; string str3;int int1; int int2; int int3; int int4; int int5;float flt1; float flt2;};

tuple tsi{string str1; int int1;};

 

//Input initiation

{t3s5i2f} setWOA = ...;

{tsi} TravIndex = {<trav,out_ww>|<facility,area,trav,rec,step,ws,step_ww,out_ww,woa,yld> in setWOA};

 

//constraint Definition

constraint ctbendMinWO[TravIndex];

 

part of the lp file generated:

ctbendMinWO({,201949})

 

I expect to see:

ctbendMinWO({"ABC",201949}), as "ABC" is the string that forms the first element of the tuple structure {tsi}.

 

It seems like only the integer elements of the tuple is getting generated in the lp. Am I doing anything wrong? Or, is this a limitation?

 

 

 

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Originally posted by: naveendivakaran

I think I found the answer to this myself. The constraint definition in the mod file was:

 

 

When i rewrite it as:

it shows the string. But I am still curious why the initial code wont work.

 

I still have a question though. It seems like the string works differently for constraint name and variable. When the variables seem to replace space by a dot, the constraint name seems to replace space by an under score. Could I somehow make the variable and constraint naming use the same formatting?

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

I tried

tuple tsi{string str1; int int1;};

{tsi} s={<"a",1>,<"b",2>};

dvar int x[s];

constraint ct2[s];

subject to
{
forall(i in s) ct:x[i]<=i.int1;

forall(i in s) ct2[i]:x[i]<=i.int1;
}

main
{
thisOplModel.generate();

cplex.exportModel("test.lp");
}

which gives

\ENCODING=ISO-8859-1
\Problem name: array

Minimize
 obj:
Subject To
 ct({"a",1}):  x({"a",1}) <= 1
 ct({"b",2}):  x({"b",2}) <= 2
 ct2({"a",1}): x({"a",1}) <= 1
 ct2({"b",2}): x({"b",2}) <= 2
Bounds
      x({"a",1}) Free
      x({"b",2}) Free
Generals
 x({"a",1})  x({"b",2})
End

same with

tuple tsi{string str1; int int1;};

{tsi} s={<"a",1>,<"b",2>};

dvar int x[s];

constraint ct2[s];

subject to
{
forall(<a,b> in s) ct:x[<a,b>]<=b;

forall(<a,b> in s) ct2[<a,b>]:x[<a,b>]<=b;
}

main
{
thisOplModel.generate();

cplex.exportModel("test2.lp");
}

regards

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#OPLusingCPLEXOptimizer