Capturing a scalar constraint results in an IntVar

Question

I’m posting a scalar constraint and I’d like to be able to print its result out when I get a solution. So I’d like to somehow cache it in an IntVar…

I found an old answer with the old Choco syntax and I’m just not able to make it work with the modern Choco:

pb.post(eq(y, pb.scalar(new IntDomainVar(){x1,x2,...,xn}, new int[]{1,1...,1})));

Maybe it’s not exactly what I’m looking for because y might just be an int constant and not an IntVar…

Anyway, do you know a way to do that? For the moment I could recompute the scalar from the values when I get the solution, but I’m planning to add a minimize objective based on the average of those scalars…

I’ve tried to work around this by decomposing the scalar into several variables but now I’m getting zero solutions:

IntVar[][] scalarResults = new IntVar[x][y];
IntVar[] sumsOfScalars = new IntVar[x];
IntVar[] sumsOfScalars = model.intVarArray(x, 0, ub);

for (int i = 0; i < x; i++) {
    for (int j = 0; j < y; j++) {

        scalarResults[i][j] = model.intScaleView(mainValues[i][j], coeffs[j]);
        // Works great.

        model.sum(scalarResults[i], "=", sumsOfScalars[i]).post();
    }
}

What am I doing wrong? Thanks for any help!

Maybe this answer helps: https://stackoverflow.com/a/47605760/4424646 — Tobi Tiggers, Apr 16 '18 at 11:32
Thanks! If “capacity” in the example can be a variable and not only a constant, it could work. I’ll try it! — wdyp, Apr 18 '18 at 21:49

Capturing a scalar constraint results in an IntVar

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