GRBConstr#

GRBConstr#

Gurobi constraint object. Constraints are always associated with a particular model. You create a constraint object by adding a constraint to a model (using GRBModel.addConstr), rather than by using a GRBConstr constructor.

The methods on constraint objects are used to get and set constraint attributes. For example, constraint right-hand sides can be queried by calling get (GRB.DoubleAttr.RHS). Note, however, that it is generally more efficient to query attributes for a set of constraints at once. This is done using the attribute query method on the GRBModel object (GRBModel.get).

char get(GRB.CharAttr attr)#

Query the value of a char-valued attribute.

Arguments:

attr – The attribute being queried.

Return value:

The current value of the requested attribute.

Example:
// Get constraint sense
char sense = constr.get(GRB.CharAttr.Sense);
double get(GRB.DoubleAttr attr)#

Query the value of a double-valued attribute.

Arguments:

attr – The attribute being queried.

Return value:

The current value of the requested attribute.

Example:
// Get RHS of the constraint
double rhs = constr.get(GRB.DoubleAttr.RHS);
int get(GRB.IntAttr attr)#

Query the value of an int-valued attribute.

Arguments:

attr – The attribute being queried.

Return value:

The current value of the requested attribute.

Example:
// Get CBasis value
int cbasis = constr.get(GRB.IntAttr.CBasis);
String get(GRB.StringAttr attr)#

Query the value of a string-valued attribute.

Arguments:

attr – The attribute being queried.

Return value:

The current value of the requested attribute.

Example:
// Get constraint name
String name = constr.get(GRB.StringAttr.ConstrName);
int index()#

This method returns the current index, or order, of the constraint in the underlying constraint matrix.

Note that the index of a constraint may change after subsequent model modifications.

Return value:

-2: removed, -1: not in model, otherwise: index of the constraint in the model

Example:
// Get the index of the constraint in the model
int index = constr.index();
boolean sameAs(GRBConstr otherConstr)#

Check whether two constraint objects refer to the same constraint.

Arguments:

otherConstr – The other constraint.

Return value:

Boolean result indicates whether the two constraint objects refer to the same model constraint.

Example:
// Compare the constraint with another constraint
boolean isSame = constr.sameAs(otherConstr);
void set(GRB.CharAttr attr, char newval)#

Set the value of a char-valued attribute.

Arguments:

  • attr – The attribute being modified.

  • newval – The desired new value of the attribute.

Example:
// Set constraint sense
constr.set(GRB.CharAttr.Sense, '>');
void set(GRB.DoubleAttr attr, double newval)#

Set the value of a double-valued attribute.

Arguments:

  • attr – The attribute being modified.

  • newval – The desired new value of the attribute.

Example:
// Set RHS of the constraint
constr.set(GRB.DoubleAttr.RHS, 2.0);
void set(GRB.IntAttr attr, int newval)#

Set the value of an int-valued attribute.

Arguments:

  • attr – The attribute being modified.

  • newval – The desired new value of the attribute.

Example:
// Set CBasis value
constr.set(GRB.IntAttr.CBasis, 0);
void set(GRB.StringAttr attr, String newval)#

Set the value of a string-valued attribute.

Arguments:

  • attr – The attribute being modified.

  • newval – The desired new value of the attribute.

Example:
// Set constraint name
constr.set(GRB.StringAttr.ConstrName, "newName");