org.jamesframework.core.subset.neigh

Class SingleAdditionNeighbourhood

java.lang.Object

org.jamesframework.core.subset.neigh.SubsetNeighbourhood

org.jamesframework.core.subset.neigh.SingleAdditionNeighbourhood

All Implemented Interfaces:

Neighbourhood<SubsetSolution>

public class SingleAdditionNeighbourhood
extends SubsetNeighbourhood

A subset neighbourhood that generates addition moves only (see AdditionMove). An addition move is a subtype of SubsetMove that adds a single ID to the selection of a subset solution. If desired, a set of fixed IDs can be provided which are not allowed to be added to the selection. Also, a size limit can be imposed so that no moves are generated when the current solution has maximum size.

Note that this neighbourhood is thread-safe: it can be safely used to concurrently generate moves in different searches running in separate threads.

Author:

Herman De Beukelaer

Constructor Summary

Constructors

Constructor and Description
SingleAdditionNeighbourhood() Create a single addition neighbourhood without maximum subset size.
SingleAdditionNeighbourhood(int maxSubsetSize) Create a single addition neighbourhood with a given limit on the number of selected items (maximum subset size).
SingleAdditionNeighbourhood(int maxSubsetSize, Set<Integer> fixedIDs) Create a single addition neighbourhood with a limit on the number of selected items (subset size) and a given set of fixed IDs which are not allowed to be selected.

Method Summary

Modifier and Type	Method and Description
List<SubsetMove>	getAllMoves(SubsetSolution solution) Generates a list of all possible addition moves that add a single ID to the selection of a given subset solution.
int	getMaxSubsetSize() Get the maximum subset size.
SubsetMove	getRandomMove(SubsetSolution solution, Random rnd) Generates a random addition move for the given subset solution that adds a single ID to the selection.

Methods inherited from class org.jamesframework.core.subset.neigh.SubsetNeighbourhood

getAddCandidates, getRemoveCandidates

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jamesframework.core.search.neigh.Neighbourhood

getRandomMove

Constructor Detail

SingleAdditionNeighbourhood

public SingleAdditionNeighbourhood()

Create a single addition neighbourhood without maximum subset size. All items are candidates to be selected.

SingleAdditionNeighbourhood

public SingleAdditionNeighbourhood(int maxSubsetSize)

Create a single addition neighbourhood with a given limit on the number of selected items (maximum subset size). No moves will be generated if the maximum subset size would be exceeded. All items are candidates to be selected.

Parameters:

maxSubsetSize - maximum subset size (> 0)

Throws:

IllegalArgumentException - if maximum subset size is not strictly positive

SingleAdditionNeighbourhood

public SingleAdditionNeighbourhood(int maxSubsetSize,
                                   Set<Integer> fixedIDs)

Create a single addition neighbourhood with a limit on the number of selected items (subset size) and a given set of fixed IDs which are not allowed to be selected. None of the generated addition moves will add any of these IDs.

Parameters:

maxSubsetSize - maximum subset size (> 0)

fixedIDs - set of fixed IDs which are not allowed to be added to the selection

Throws:

IllegalArgumentException - if maximum subset size is not strictly positive

Method Detail

getMaxSubsetSize

public int getMaxSubsetSize()

Get the maximum subset size. If no size limit has been applied this method returns Integer.MAX_VALUE.

Returns:

maximum subset size

getRandomMove

public SubsetMove getRandomMove(SubsetSolution solution,
                                Random rnd)

Generates a random addition move for the given subset solution that adds a single ID to the selection. Possible fixed IDs are not considered to be added and the maximum subset size is taken into account. If no addition move can be generated, null is returned.

Parameters:

solution - solution for which a random addition move is generated

rnd - source of randomness used to generate random move

Returns:

random addition move, null if no move can be generated

getAllMoves

public List<SubsetMove> getAllMoves(SubsetSolution solution)

Generates a list of all possible addition moves that add a single ID to the selection of a given subset solution. Possible fixed IDs are not considered to be added and the maximum subset size is taken into account. May return an empty list if no addition moves can be generated.

Parameters:

solution - solution for which all possible addition moves are generated

Returns:

list of all addition moves, may be empty