Originally posted by: sandeepsinghchauhan

A is a matrix

                   col1    col2    col3

A =   row1   4          5         8

        row2   0          5         0

        row3    2         0          0

I want to calculate number of non zeros elements in columns like in col1 number of non zeros are 2 , col2 has 1 and col3 has 2

how can i do in opl

Hi

execute
{
writeln(cplex.getNNZs());
}

regards

Originally posted by: sandeepsinghchauhan

execute
{

for(var x in 1..3) {
NZ[x]  = writeln(cplex.getNNZs(A));
}

}

ERROR
Scripting runtime error: (in getNNZs) too many arguments.  

Hi,

no direct way to do that as far as I know.

You could modify the matrix and compute those numbers by comparing.

Let me give you an example:

dvar float+ Gas;
dvar float+ Chloride;

maximize
  40 * Gas + 50 * Chloride;
subject to {
  ctMaxTotal:     
    Gas + Chloride <= 50;
  ctMaxTotal2:    
    3 * Gas + 4 * Chloride <= 180;
  ctMaxChloride:  
    Chloride <= 40;
}

tuple SolutionT{
    float Gas;
    float Chloride;
};
{SolutionT} Solution = {<Gas,Chloride>};
execute{
    writeln(Solution);
}

execute
{
var nnz;

writeln("NNZ=",nnz=cplex.getNNZs());

thisOplModel.ctMaxTotal.setCoef(Gas,0);
thisOplModel.ctMaxTotal2.setCoef(Gas,0);
thisOplModel.ctMaxChloride.setCoef(Gas,0);

var nnzGas=nnz-cplex.getNNZs();

thisOplModel.ctMaxTotal.setCoef(Chloride,0);
thisOplModel.ctMaxTotal2.setCoef(Chloride,0);
thisOplModel.ctMaxChloride.setCoef(Chloride,0);

var nnzChloride=nnz-nnzGas-cplex.getNNZs();

writeln("NNZ Gas and Chloride = ",nnzGas," ",nnzChloride);

}

which gives

NNZ=5
NNZ Gas and Chloride = 2 3

regards

Hi,

you could also have a look at https://www.ibm.com/developerworks/community/forums/html/topic?id=51f87068-85ca-4a8c-9931-b516bdd69f1e

and you could also do that in Python.

regards

So with the getters you could write:

dvar float+ Gas;
dvar float+ Chloride;

maximize
  40 * Gas + 50 * Chloride;
subject to {
  ctMaxTotal:     
    Gas + Chloride <= 50;
  ctMaxTotal2:    
    3 * Gas + 4 * Chloride <= 180;
  ctMaxChloride:  
    Chloride <= 40;
}

tuple SolutionT{
    float Gas;
    float Chloride;
};
{SolutionT} Solution = {<Gas,Chloride>};
execute{
    writeln(Solution);
}

 

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

var nbNNZGas=(cplex.getCoef(thisOplModel.ctMaxTotal,thisOplModel.Gas)!=0)+
(cplex.getCoef(thisOplModel.ctMaxTotal2,thisOplModel.Gas)!=0)+
(cplex.getCoef(thisOplModel.ctMaxChloride,thisOplModel.Gas)!=0);

var nbNNZChloride=(cplex.getCoef(thisOplModel.ctMaxTotal,thisOplModel.Chloride)!=0)+
(cplex.getCoef(thisOplModel.ctMaxTotal2,thisOplModel.Chloride)!=0)+
(cplex.getCoef(thisOplModel.ctMaxChloride,thisOplModel.Chloride)!=0);
writeln(nbNNZGas);
writeln(nbNNZChloride);

}

regards