Problem with automating testing of multiple scenarios in IBM ILOG CPLEX Optimization Studio: change the parameters between each test

Question

I am having trouble automating the testing of several scenarios with CPLEX.

I want to test several scenarios where I play around with the weight of the weighted sum of my objective function and the ratio.

Example: W1=0.2, W2 = 0.7, and W3=0.1 with

ratio\[1\]=0
ratio\[2\]=0
ratio\[3\]=0

to start with. Then, I want my code to increment only ratio[3] from 0.1 to 0.7.

The problem I have is that my code only executes the first base value. It writes all the different W and ratio[i] values to my Excel file, but it always keeps the same value for my parameters. How can I link my constraints to the main? Compared to my first message, I have indicated how I declare my variables and parameters for clarity. In addition, I tried adding thisOplModel.W1 = currentW[1], but this gives me an error message.

Here are my variables:

COUTTOTAL: Total cost to complete the project.
Cmax: Time to complete the project.
QTEREMP: Quantity reused. Compared to the other two, we want to maximize this variable.

Parameters:

W1, W2, and W3 are the weights assigned by the user.
S1, S2, and S3 are correction factors to ensure that each variable has the same degree of importance.
esti***: Maximum and minimum values depending on whether I maximize or minimize just one variable.

FYI: I tried using Gemini to help me execute the automation portion. I can change that part without any problems.

code.mod

float estiTempsMax =...;
float estiCoutMax=...;
float estiTempsMin =...;
float estiCoutMin=...;
float estiQTEMin=...;
float estiQTEMax=...;
float W1;
float W2;
float W3;
float WMAX=...;
float S1=W1/WMAX;
float S2=W2/WMAX;
float S3=W3/WMAX;
float W_combinaisons[Mode][Mode]=...;
float ratio[Mode];
float ratio_script[Mode]= [0, 0, 0];

dvar int Cmax;
dvar float QTEREMP;
dvar float COUTTOTAL;
dexpr float TestCOU = ctCont+ ctLiv + ctMO  + ctDecMat + ctEquip +  ENF +ctRecyc - gain;
dexpr float TestQTE = sum(m in Mat) Qm[3][m];

minimize W1 *S1*((TOTALCOST-estiMinCost)/(estiMaxCost-estiMinCost)) +     W2*S2*((Cmax-estiMinTime)/(estiMaxTime-estiMinTime)) - W3*S3*((QTEREMP-estiMinQTEM)/(estiMaxQTEM-estiMinQTEM));

//Constrait....
subject to {
...
    forall(i in Mode)
        CtRatioLiaison: ratio[i] == ratio_script[i]; //I'M TRYING TO LINK MY PARAMETERS WITH THE MAIN
...
}


main {
    var ofile = new IloOplOutputFile("resultats_scenarios_ratio2_varie.csv");
    ofile.writeln("W1;W2;W3;ratio[1];ratio[2];ratio[3];Objectif;COUTTOTAL;Cmax;QTEREMP");

    var r2_start = 0.0;
    var r2_end = 0.2;
    var r2_step = 0.1;

    for (var r2_val = r2_start; r2_val <= r2_end + 0.0001; r2_val += r2_step) { 
        for (var w_index = 1; w_index <= 3; w_index++) { 
            
            var currentW = thisOplModel.W_combinaisons[w_index]; 
            
            W1 = currentW[1];
            W2 = currentW[2];
            W3 = currentW[3];

            for (var r3 = 0.0; r3 <= 0.7 + 0.0001; r3 += 0.1) {
                
             
                var tempRatio = new Array(4); // Taille 4 pour supporter les index 1, 2, 3

                tempRatio[1] = 0.0;     
                tempRatio[2] = r2_val;  
                tempRatio[3] = r3;     
                
                 thisOplModel.generate()
                writeln("--- Résolution : R2=", ratio_script[2], ", W=(", W1, ", ", W2, ", ", W3, ") et R3=", ratio_script[3], " ---");

        if (cplex.solve()) {
    
            ofile.writeln(W1, ";", W2, ";", W3, ";", 
                    //CORRECTION : Utiliser ratio_script au lieu de ratio
                                ratio_script[1], ";", ratio_script[2],    ";",ratio_script[3], ";",cplex.getObjValue(), ";", thisOplModel.TestCOU, ";", thisOplModel.Cmax, ";", thisOplModel.QTEREMP);

} 
                else {
                     ofile.writeln(W1, ";", W2, ";", W3, ";", 
                    ratio_script[1], ";", ratio_script[2], ";", ratio_script[3], ";",
                    "No Solution", ";", "N/A", ";", "N/A", ";", "N/A");
                    }
                 }
        }
    }

Any solution ?

Alex Fleischer · Accepted Answer · 2025-11-20 17:52:06Z

While github is down let me share the examples about updating an array and solving again I shared at Change a 2D array and solve again

Suppose you have sub2d.mod

    int y[1..2][1..2]=...;

    execute
    {
    writeln("y=",y);
    }

    dvar float x;

    maximize x;
    subject to {
      x<=sum(i in 1..2, j  in 1..2) y[i][j];
    }

Then

if you run

   int a[1..2][1..2];

    main {
      var source = new IloOplModelSource("sub2d.mod");
      var cplex = new IloCplex();
      var def = new IloOplModelDefinition(source);
     
     
     
      for(var k=11;k<=15;k++)
      {
      var opl = new IloOplModel(def,cplex);
     
     
        
      var data2= new IloOplDataElements();
     
      data2.y=thisOplModel.a;
      data2.y[1][1]=k;
      opl.addDataSource(data2);
     
      opl.generate();

      if (cplex.solve()) {
         writeln("OBJ = " + cplex.getObjValue());
      } else {
         writeln("No solution");
      }
      data2.end();
     opl.end();
     
     
    }  
     
    }

you get

    y= [[11 0]
             [0 0]]
    OBJ = 11
    y= [[12 0]
             [0 0]]
    OBJ = 12
    y= [[13 0]
             [0 0]]
    OBJ = 13
    y= [[14 0]
             [0 0]]
    OBJ = 14
    y= [[15 0]
             [0 0]]
    OBJ = 15

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