Class IloNHood

This handle class is used to define neighborhood structures that can be used by local search procedures. The central idea of the neighborhood is to define a set of solution changes, or deltas, that represent alternative moves that can be taken.

Protocol

The protocol for driving an object of type IloNHood is as follows:

For more information, see IloSolution in the IBM ILOG Concert Technology Reference Manual.

This constructor creates a neighborhood whose implementation pointer is 0 (zero). The handle must be assigned before its methods can be used.

This constructor creates a handle object (an instance of the class IloNHood) from a pointer to an implementation object (an instance of the class IloNHoodI).

This constructor creates a handle object from a reference to a neighborhood. After execution, both the newly constructed handle object and nhood point to the same implementation object.

This member function returns the change in the current solution to be made when making move index in the neighborhood. The neighbors are numbered from 0. If an empty handle is returned, no change is defined for this index.

The argument solver indicates the solver that is scanning the invoking neighborhood. (See IloScanNHood.)

This member function calls delete on the implementation object associated with the invoking handle and sets the implementation pointer to 0. If the invoking neighborhood has any children (for instance, if it were constructed using a + operator) then these too will be likewise deleted. If, however, deep has the value IloFalse, then the children are “disconnected” from the parent before delete is called on the implementation pointer to ensure that the children of the invoking neighborhood are not destroyed.

This member function returns the environment associated with the implementation class.

This member function returns the implementation object of the invoking handle. You can use this member function to check whether a neighborhood is empty.

This member function converts the index index to the index in the atomic neighborhood responsible for defining neighbor index. This member function is useful for finding the index in the neighborhood that defined a neighbor when the invoking neighborhood is made up of neighborhoods combined via concatenation (operator operator+ or IloConcatenate). It is also useful when the invoking neighborhood has been modified (for instance via IloRandomize). In typical usage, the index passed originates from an instance of IloNeighborIdentifier.

This member function returns the atomic neighborhood responsible for defining the neighbor indexed index. This member function is useful for finding the exact neighborhood that defined a neighbor when the invoking neighborhood is made up of neighborhoods combined via (operator+ or IloConcatenate). In typical usage, the index passed originates from an instance of IloNeighborIdentifier.

This member function returns a character string specifying the name of the invoking object (if there is one).

This member function returns the object associated with the invoking object (if there is one). Normally, an associated object contains user data pertinent to the invoking object.

This member function returns the “size” of the neighborhood, that is, one more than the maximum index that IloNHood::define can legally be called with. The argument solver indicates the solver that is scanning the invoking neighborhood. (See IloScanNHood.)

This member function is called when a neighborhood move is about to be taken. It is called with index equal to the index of the neighbor currently being accepted by local search. The argument solver indicates the solver that is scanning the invoking neighborhood. (See IloScanNHood.)

At the point of calling, the constrained variables corresponding to the solution passed to IloNHood::start should be instantiated, but not yet been saved to the current solution. This allows inspection of the differences. Default behavior is to do nothing.

This member function is a counterpart to IloNHood::notify. When neighborhoods are joined with operator+ or IloConcatenate, only one basic neighborhood can have IloNHood::notify called: the one that defined the delta for the move to be taken. For all other basic neighborhoods, notifyOther is called with the delta for the move to be taken.

The argument solver indicates the solver that is scanning the invoking neighborhood. (See IloScanNHood.)

This assignment operator copies nhood into the invoking neighborhood by assigning an address to the handle pointer of the invoking object. That address is the location of the implementation object of the argument nhood.

This member function resets the neighborhood to the state in which it was first created. For neighborhoods which have no state, calling this member function has no effect. An example of a neighborhood with state is IloContinue which, after each move, adjusts neighborhood indices to ensure that new indices are explored. When neighborhoods have state, you will typically want to call this member function between two different local searches if the neighborhood is to be reused. Most of Solver's neighborhoods are stateless.

This member function assigns name to the invoking object.

This member function associates obj with the invoking object. The member function getObject accesses this associated object afterward. Normally, obj contains user data pertinent to the invoking object.

This member function announces to the neighborhood that neighbors will be requested of it (through IloNHood::define), and that current is the reference point of these changes. That is, all changes specified afterwards via calls to IloNHood::define (until start is called again) should relate to changes of current.

The argument solver indicates the solver that is scanning the invoking neighborhood. (See IloScanNHood.)