Visual Basic Attribute Examples

Consider the case where you have a Gurobi model <span>$</span>m<span>$</span>. You can retrieve the number of variables in the model by querying the NumVars model attribute (which is implemented as a .NET property):

  cols = m.NumVars;

If you've performed optimization on the model, the optimal objective value can be obtained by querying the ObjVal model attribute:

  obj = m.ObjVal;

If you'd like to query the value that a variable takes in the computed solution, you can query the X attribute for the corresponding variable object:

  vars = m.GetVars()
  For j As Integer = 0 To cols - 1
    xj = vars[j].X
You can also query the value of <span>$</span>X<span>$</span> for multiple variables in a single call using the Get method on the model <span>$</span>m<span>$</span>:
  xvals = m.Get(GRB.DoubleAttr.X, m.GetVars()))

For each attribute query method, there's an analogous <span>$</span>Set<span>$</span> routine. To set the upper bound of a variable, for example:

  v = m.GetVars()[0]
  v.UB = 0
(In this example, we've set the upper bound for the first variable in the model to 0).

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