Originally posted by: MJCplex

Hi everyone,

 

I have been using the forum for quite a while and found many great solutions to minor problems I have had - thanks for that already!

But right now I got stuck on a problem that I can't find a solution to - so maybe you can help me with my first post:

 

I have created a program with flow control using a main.mod and an additional loop.mod.

Each iteration the loop.mod is solved and the found solution is added to a set of penalized solutions for the next iteration (so that the solution is more unlikely to be found again in the next iteration).

Once a solution has been found a second time the program stops.

 

Everything is running as expected as long as I only try to read from the excel-file for the initial parameters.

Any attempts to write the found solutions to excel failed so far - the corresponding line in the .dat file is completly skipped.

I also added .postProcess() after each .generate() in the loop, but the SheetWrite-command is still ignored.

It does not even cause an error when I have the excel-file open while executing the program (which usually leads to the 'file is read-only' error).

 

As the model itself got quite big by now I try to bring it down to the essential part :

main.mod:

//---------- Solving the base model without penalties ----------------------

       //Creating the model

       var defBase = thisOplModel.modelDefinition;

       var cplexBase = cplex;

       var oplBase = new IloOplModel(defBase,cplexBase);

      

       //Adding the data

       var dataBase = thisOplModel.dataElements;

       oplBase.addDataSource(dataBase);

      

       //Generating the model

       oplBase.generate();

       if (cplexBase.solve())

       {

             oplBase.postProcess();

       }

       else

       {

       writeln("No Solution");

       }

....

....

....

....

while(loopCondition == 0)

{

      

       ObjValueStorage[loop] = cplexLoop.getObjValue();

       simulationObjective[loop] = ObjValueStorage[loop]*(0.4*(Opl.rand(101)/100));

      

       //add penalty from last iteration to new candidate solution

       dataLoop.P.add(loop, simulationObjective[loop]);

                   

       //add new candidate solution from last iteration

       for(var sNode = 1; sNode <= oplBase.maxNodes; sNode++)

       {

                    for(var tNode = 1; tNode <= oplBase.maxNodes; tNode++)

                    {

                           dataLoop.H.add(loop, sNode, tNode, oplLoop.x[sNode][tNode].solutionValue);                          

                    }

                   

       }

       dataLoop.r = loop;

       oplLoop = new IloOplModel(defLoop,cplexLoop);

       oplLoop.addDataSource(dataLoop);

       oplLoop.generate();

       if (cplexLoop.solve())

       {

             oplLoop.postProcess();

       }

       else

       {

       writeln("No Solution");

       }

      

       for(var iteration = 1; iteration <= loop; iteration++)

       {

             loopCondition = loopCondition + oplLoop.U[iteration].solutionValue;

       }     

}

 

.data:

SheetConnection Import("Import.xlsx");

SheetConnection Export("Export.xlsx");

//Sets / ranges

 

maxNodes from SheetRead(Import,"number_of_nodes");

 

//Parameters

 

w from SheetRead(Import,"Scaled_Flow"); //Flow originated at node i in N that is destined to node j in N.

 

f from SheetRead(Import,"Fixed_Costs"); //Fixed setup cost for location a hub at node k in N.

 

g from SheetRead(Import,"Link_Costs"); //Fixed cost for operating a hub link between hubs k in N and l in N.

        

c from SheetRead(Import,"Costs");

 

alpha from SheetRead(Import,"alpha"); //Economies of Scale discount factor for the flow transferred between hubs.

 

O from SheetRead(Import,"Origin");

D from SheetRead(Import,"Destination");

 

 

//---------------------------  exporting data

x to SheetWrite(Export,"SolutionValue");

 

Any ideas?

Thanks!

 

Best greetings,

 

MJ

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

can you try to replace

main
{
var defBase = thisOplModel.modelDefinition;

       var cplexBase = cplex;

       var oplBase = new IloOplModel(defBase,cplexBase);

      

       //Adding the data

       var dataBase = thisOplModel.dataElements;

       oplBase.addDataSource(dataBase);

      

       //Generating the model

       oplBase.generate();

       if (cplexBase.solve())

       {

             oplBase.postProcess();

       }

       else

       {

       writeln("No Solution");

       }
}

by

main
{
thisOplModel.generate();
cplex.solve();
thisOplModel.postProcess();
}

?

regards

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Or what you could also do is use an additional main.mod such as

main
{
var source = new IloOplModelSource("model.mod");
;
  var defBase = new IloOplModelDefinition(source);

       var cplexBase = cplex;

       var oplBase = new IloOplModel(defBase,cplexBase);

      

       //Adding the data

       var dataBase = new IloOplDataSource("data.dat");

       oplBase.addDataSource(dataBase);

      

       //Generating the model

       oplBase.generate();

       if (cplexBase.solve())

       {

             oplBase.postProcess();

       }

       else

       {

       writeln("No Solution");

       }
}

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: MJCplex

Hey Alex,

 

thanks for your answer!

Apparently replacing my rather complex initialization with your shorter one triggers the export to excel.

Because I actually want to understand what's going on in my model before adapting all the remaining lines of code to the new construction: Do you have any idea why my initial formulation skips the export?

 

Regarding your 2nd answer:

To my understanding cplex only allows 1 main.mod per run configuration?

Right now I use my main.mod for flow control and for the initial solution and then use another model.mod for the loop iterations.

 

Maybe to rephrase it:

Using a main.mod, a model.mod and one data.dat file, how can I create a loop where data is written to excel after each iteration, recalculated there and imported again for the next iteration (so that some values actually change in the progress)?

I am right now working on a short and simplified version to demonstrate what I am thinking about.

 

Thanks!

 

Best regards,

 

MJ

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

"Do you have any idea why my initial formulation skips the export?"  ==> No, this looks strange.

To my understanding cplex only allows 1 main.mod per run configuration?  ==> From another .mod you may call the main of another .mod , see the method main() in IloOplModel

About getting a solution and using that as input you may have a look at

https://www.ibm.com/developerworks/community/forums/html/topic?id=8d5bdc42-8b25-4e6c-928c-d0fba4862eee&ps=25

and

https://www.ibm.com/developerworks/community/forums/html/topic?id=092c58bb-7bc8-4121-b3d9-91c07424c586

Plus some useful links at

https://www.ibm.com/developerworks/community/forums/html/topic?id=0d0b2396-3b48-4638-b032-3b9ea74f1a11&ps=25

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer