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).

The full list of attributes can be found in the Attributes section of this document. Examples of how to query and set attributes can also be found in this section.

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");