ilog.opl

Class IloCplex.NodeCallback

java.lang.Object

ilog.opl.IloCplex.Callback

ilog.opl.IloCplex.MIPInfoCallback

ilog.opl.IloCplex.MIPCallback

ilog.opl.IloCplex.NodeCallback

All Implemented Interfaces:

java.lang.Cloneable

Enclosing class:

IloCplex

public abstract static class IloCplex.NodeCallback
extends IloCplex.MIPCallback

This is the base class for user-written callbacks that allow the user to select the node to process next during the branch-and-cut search.

Node callbacks allow you to determine which node from among the unexplored nodes IloCplex will chose to explore next in the branch-and-cut search. They aslo give you the option to override this selection.

When an instance of this callback class executes, the invoking instance of IloCplex still has n = getNremainingNodes (inherited from MIPCallback) nodes left to process. These remaining nodes are numbered from 0 (zero) to n-1. For that reason, the same node may have a different number each time an instance of NodeCallback is called. To identify a node uniquely, an instance of IloCplex also assigns a unique identifier ( IloCplex.NodeId) to each node. That unique identifier remains unchanged throughout the search. The method getNodeId(int i) allows you to access the IloCplex.NodeId for each of the remaining nodes 0 to n-1 . Similarly, the method getNodeNumber returns the number of a node specified by its IloCplex.NodeId.

The constructor and methods of this class are protected to make sure that they are used only to derive a user-written callback class or to implement the main method in it.

See Also:

IloCplex.MIPCallback

Nested Class Summary

Nested classes/interfaces inherited from class ilog.opl.IloCplex.MIPCallback

IloCplex.MIPCallback.NodeData

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	IloCplex.NodeCallback() This is the constructor for user-written node callbacks.

Method Summary

Methods

Modifier and Type	Method and Description
protected IloNumVar	getBranchVar(int node) Returns the variable that was branched upon to create the node specified by number node.
protected int	getDepth(int node) Returns the depth of the node in the search tree.
protected double	getEstimatedObjValue(int node) Returns the estimated objective value for the node indicated by the node number node.
protected double	getInfeasibilitySum(int node) Returns the sum of integer infeasibility of the node indicated by the node number node.
protected int	getNinfeasibilities(int node) Returns the number of integer infeasible variables for the node indicated by the node number node.
protected java.lang.Object	getNodeData(int node) Returns the user object attached to the node with number node.
protected IloCplex.NodeId	getNodeId(int node) Returns the node identifier of the node indicated by the node number node.
protected int	getNodeNumber(IloCplex.NodeId nodeid) Returns the node number of the node indicated by the node identifier nodeid.
protected double	getObjValue(int node) Returns the objective value of the node indicated by the node number node.
protected void	selectNode(int node) Selects the next node to be processed by its number.
protected java.lang.Object	setNodeData(long id, java.lang.Object o)

Methods inherited from class ilog.opl.IloCplex.MIPCallback

getObjCoef, getObjCoefs, getObjCoefs, getUserThreads

Methods inherited from class ilog.opl.IloCplex.MIPInfoCallback

getBestObjValue, getCutoff, getDirection, getIncumbentObjValue, getIncumbentValue, getIncumbentValue, getIncumbentValues, getIncumbentValues, getMIPRelativeGap, getMyThreadNum, getNiterations, getNnodes, getNremainingNodes, getPriority, hasIncumbent

Methods inherited from class ilog.opl.IloCplex.Callback

abort, getCplexTime, getDetTime, getEndDetTime, getEndTime, getEnvImpl, getModel, getNcols, getNQCs, getNrows, getStartDetTime, getStartTime, main

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IloCplex.NodeCallback

protected IloCplex.NodeCallback()

This is the constructor for user-written node callbacks. This constructor can be called only to construct objects of derived user-written callback classes; it cannot be used to construct IloCplex.NodeCallback objects directly.

Method Detail

getNodeId

protected IloCplex.NodeId getNodeId(int node)
                             throws IloException

Returns the node identifier of the node indicated by the node number node. An instance of IloCplex numbers the nodes that remain to be explored in the branch and cut sequentially from 0 (zero) to getNremainingNodes()-1. However, when a node is created during search, it also assigns a unique IloCplex.NodeId to it. This method allows you to query this IloCplex.NodeId for all unexplored nodes.

Throws:

IloException

Parameters:

node - The node number of the node for which the node identifier is queried.

Returns:

The IloCplex.NodeId of the specified node.

getObjValue

protected double getObjValue(int node)
                      throws IloException

Returns the objective value of the node indicated by the node number node.

Throws:

IloException

Parameters:

node - The number of the node for which the objective value is requested.

Returns:

The objective value of node number node.

getEstimatedObjValue

protected double getEstimatedObjValue(int node)
                               throws IloException

Returns the estimated objective value for the node indicated by the node number node.

Throws:

IloException

Parameters:

node - The number of the node for which the estimated objective value is requested.

Returns:

The estimated object value for the node with node number node.

getDepth

protected int getDepth(int node)
                throws IloException

Returns the depth of the node in the search tree. The root node is defined to have depth 0 (zero); the depth of other nodes is their distance from the root or, equivalently, the number of branches needed to reach that node from the root.

Throws:

IloException

Parameters:

node - The node number of the node whose depth is being queried.

Returns:

The depth of the node with number node.

getInfeasibilitySum

protected double getInfeasibilitySum(int node)
                              throws IloException

Returns the sum of integer infeasibility of the node indicated by the node number node.

Throws:

IloException

Parameters:

node - The node number of the node whose infeasibility sum is being queried.

Returns:

The sum of integer infeasibility of the node with number node.

getNinfeasibilities

protected int getNinfeasibilities(int node)
                           throws IloException

Returns the number of integer infeasible variables for the node indicated by the node number node.

Throws:

IloException

Parameters:

node - The node number of the node whose number of integer infeasibilities is being queried.

Returns:

The number of integer infeasibilities for the node with number node.

selectNode

protected void selectNode(int node)
                   throws IloException

Selects the next node to be processed by its number.

Selects the node indicated by number node as the next node to process in the branch-and-cut search. The parameter node is the node number of the node to selected and must be between 0 (zero) and getNremainingNodes()-1.

The invoking instance of IloCplex uses the specified node as the next node to process.

Throws:

IloException

Parameters:

node - The number of the node you want to be processed next.

getBranchVar

protected IloNumVar getBranchVar(int node)
                          throws IloException

Returns the variable that was branched upon to create the node specified by number node. If that node has been created by branching on a constraint or on multiple variables, null will be returned.

Throws:

IloException

Parameters:

node - The number of the node from which you want to obtain the variable.

Returns:

The branch variable of the node with number node.

getNodeData

protected java.lang.Object getNodeData(int node)
                                throws IloException

Returns the user object attached to the node with number node. User objects can be attached to a node when the node is created with method IloCplex.BranchCallback.makeBranch in a branch callback.

Throws:

IloException

Returns:

The user object attached to the node with number node. If no user object is attached to the current node, null will be returned.

setNodeData

protected java.lang.Object setNodeData(long id,
                           java.lang.Object o)
                                throws IloException

Throws:

IloException

getNodeNumber

protected int getNodeNumber(IloCplex.NodeId nodeid)
                     throws IloException

Returns the node number of the node indicated by the node identifier nodeid.

An instance of IloCplex assigns node identifiers to nodes when it creates them while branching. Within a search, these node identifiers are unique throughout the duration of that search. However, the remaining nodes are implicitly numbered starting from 0 (zero) at each node. This method returns the number that the node with the specified identifier has within that local numbering.

Throws:

IloException

Parameters:

nodeid - The node identifier of the for which to query the ndoe number.

Returns:

The number of the node.