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 aGRBConstr
constructor.- Example:
// Create variables GRBVar x = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x"); GRBVar y = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y"); // Add linear constraint x + y = 0 with name c1 GRBConstr constr = model.AddConstr(x + y == 0, "c1");
' Create variables Dim x As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, GRB.INFINITY, 0.0, GRB.CONTINUOUS, "y") ' Add linear constraint x + y = 0 with name c1 Dim constr As GRBConstr = model.AddConstr(x + y == 0, "c1")
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 theGRBModel
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.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get constraint sense char sense = constr.Get(GRB.CharAttr.Sense);
' Get constraint sense Dim sense As Char = constr.Get(GRB.CharAttr.Sense)
- double Get(GRB.DoubleAttr attr)#
Query the value of a double-valued attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get RHS double rhs = constr.Get(GRB.DoubleAttr.RHS);
' Get RHS Dim rhs As Double = constr.Get(GRB.DoubleAttr.RHS)
- int Get(GRB.IntAttr attr)#
Query the value of an int-valued attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get CBasis value int cbasis = constr.Get(GRB.IntAttr.CBasis);
' Get CBasis value Dim cbasis As Integer = constr.Get(GRB.IntAttr.CBasis)
- string Get(GRB.StringAttr attr)#
Query the value of a string-valued attribute.
- Parameters:
attr – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
// Get constraint name string name = constr.Get(GRB.StringAttr.ConstrName);
' Get constraint name Dim name As String = constr.Get(GRB.StringAttr.ConstrName)
- int Index#
This property 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.
- Returns:
-2: removed, -1: not in model, otherwise: index of the constraint in the model
- Example:
int index = constr.Index;
Dim index As Integer = constr.Index
- bool SameAs(GRBConstr constr2)#
Check whether two constraint objects refer to the same constraint.
- Parameters:
constr2 – The other constraint.
- Returns:
Boolean result indicates whether the two constraint objects refer to the same model constraint.
- Example:
// Compare to a second constraint bool isSame = constr.SameAs(constr2);
' Compare to a second constraint Dim isSame As Boolean = constr.SameAs(constr2)
- void Set(GRB.CharAttr attr, char newvalue)#
Set the value of a char-valued attribute.
- Parameters:
attr – The attribute being modified.
newvalue – The desired new value of the attribute.
- Example:
// Set constraint sense constr.Set(GRB.CharAttr.Sense, '>');
' Set constraint sense constr.Set(GRB.CharAttr.Sense, ">")
- void Set(GRB.DoubleAttr attr, double newvalue)#
Set the value of a double-valued attribute.
- Parameters:
attr – The attribute being modified.
newvalue – The desired new value of the attribute.
- Example:
// Set RHS constr.Set(GRB.DoubleAttr.RHS, 2.0);
' Set RHS constr.Set(GRB.DoubleAttr.RHS, 2.0)
- void Set(GRB.IntAttr attr, int newvalue)#
Set the value of an int-valued attribute.
- Parameters:
attr – The attribute being modified.
newvalue – The desired new value of the attribute.
- Example:
// Set CBasis value constr.Set(GRB.IntAttr.CBasis, 0);
' Set CBasis value constr.Set(GRB.IntAttr.CBasis, 0)
- void Set(GRB.StringAttr attr, string newvalue)#
Set the value of a string-valued attribute.
- Parameters:
attr – The attribute being modified.
newvalue – The desired new value of the attribute.
- Example:
// Set constraint name constr.Set(GRB.StringAttr.ConstrName, "newName");
' Set constraint name constr.Set(GRB.StringAttr.ConstrName, "newName")