Module org.cicirello.chips_n_salsa
Class ScrambleMutation
 java.lang.Object

 org.cicirello.search.operators.permutations.ScrambleMutation

 All Implemented Interfaces:
Splittable<MutationOperator<Permutation>>
,MutationOperator<Permutation>
 Direct Known Subclasses:
WindowLimitedScrambleMutation
public class ScrambleMutation extends Object implements MutationOperator<Permutation>
This class implements a scramble mutation on permutations, where one mutation consists in randomizing the order of a randomly selected subpermutation. The pair of indexes that indicate the subpermutation to scramble is chosen uniformly at random from among all n(n1)/2 possible pairs of indexes, where n is the length of the permutation.
The runtime (worst case and average case) of the
mutate
method is O(n), where n is the length of the permutation. The worst case runtime occurs when the random indexes are the two end points. On average, a scramble mutation moves approximately n/3 elements.


Constructor Summary
Constructors Constructor Description ScrambleMutation()
Constructs a ScrambleMutation mutation operator.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
mutate(Permutation c)
Mutates a candidate solution to a problem, by randomly modifying its state.ScrambleMutation
split()
Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms.



Method Detail

mutate
public final void mutate(Permutation c)
Description copied from interface:MutationOperator
Mutates a candidate solution to a problem, by randomly modifying its state. The mutant that is produced is in the local neighborhood of the original candidate solution. Specified by:
mutate
in interfaceMutationOperator<Permutation>
 Parameters:
c
 The candidate solution subject to the mutation. This method changes the state of c.

split
public ScrambleMutation split()
Description copied from interface:Splittable
Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms. The state of the object that is returned may or may not be identical to that of the original. Thus, this is a distinct concept from the functionality of theCopyable
interface. Classes that implement this interface must ensure that the object returned performs the same functionality, and that it does not share any state data that would be either unsafe or inefficient for concurrent access by multiple threads. The split method is allowed to simply return the this reference, provided that it is both safe and efficient for multiple threads to share a single copy of the Splittable object. The intention is to provide a multithreaded search with the capability to provide spawned threads with their own distinct search operators. Such multithreaded algorithms can call the split method for each thread it spawns to generate a functionally identical copy of the operator, but with independent state. Specified by:
split
in interfaceSplittable<MutationOperator<Permutation>>
 Returns:
 A functionally identical copy of the object, or a reference to this if it is both safe and efficient for multiple threads to share a single instance of this Splittable object.

