Package org.cicirello.search.restarts
Class ReoptimizableMultistarter<T extends Copyable<T>>
- java.lang.Object
-
- org.cicirello.search.restarts.Multistarter<T>
-
- org.cicirello.search.restarts.ReoptimizableMultistarter<T>
-
- Type Parameters:
T
- The type of object being optimized.
- All Implemented Interfaces:
Splittable<TrackableSearch<T>>
,Metaheuristic<T>
,ReoptimizableMetaheuristic<T>
,TrackableSearch<T>
public final class ReoptimizableMultistarter<T extends Copyable<T>> extends Multistarter<T> implements ReoptimizableMetaheuristic<T>
This class is used for implementing multistart metaheuristics, that can be restarted at previously found solutions. It can be used to restart any class that implements theReoptimizableMetaheuristic
interface, and requires specification of either aRestartSchedule
for the purpose of specifying run lengths for the restarts, or a run length if all runs are to be of the same length. A multistart metaheuristic returns the best result from among all of the restarts.
-
-
Constructor Summary
Constructors Constructor Description ReoptimizableMultistarter(ReoptimizableMetaheuristic<T> search, int runLength)
Constructs a multistart metaheuristic that executes multiple runs of a specified metaheuristic, whose runs are all the same in length.ReoptimizableMultistarter(ReoptimizableMetaheuristic<T> search, RestartSchedule r)
Constructs a multistart metaheuristic that executes multiple runs of a specified metaheuristic, whose run lengths follow a specified schedule.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description SolutionCostPair<T>
reoptimize(int numRestarts)
Executes a multistart search, calling the underlying metaheuristic the specified number of times, keeping track of the best solution across the multiple runs of the search.ReoptimizableMultistarter<T>
split()
Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms.-
Methods inherited from class org.cicirello.search.restarts.Multistarter
getProblem, getProgressTracker, getTotalRunLength, optimize, setProgressTracker
-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
-
Methods inherited from interface org.cicirello.search.Metaheuristic
optimize
-
Methods inherited from interface org.cicirello.search.TrackableSearch
getProblem, getProgressTracker, getTotalRunLength, setProgressTracker
-
-
-
-
Constructor Detail
-
ReoptimizableMultistarter
public ReoptimizableMultistarter(ReoptimizableMetaheuristic<T> search, RestartSchedule r)
Constructs a multistart metaheuristic that executes multiple runs of a specified metaheuristic, whose run lengths follow a specified schedule.- Parameters:
search
- The metaheuristic to restart multiple times.r
- The schedule of run lengths for the multistart search
-
ReoptimizableMultistarter
public ReoptimizableMultistarter(ReoptimizableMetaheuristic<T> search, int runLength)
Constructs a multistart metaheuristic that executes multiple runs of a specified metaheuristic, whose runs are all the same in length.- Parameters:
search
- The metaheuristic to restart multiple times.runLength
- The length of every restarted run of the metaheuristic.- Throws:
IllegalArgumentException
- if runLength < 1
-
-
Method Detail
-
reoptimize
public SolutionCostPair<T> reoptimize(int numRestarts)
Executes a multistart search, calling the underlying metaheuristic the specified number of times, keeping track of the best solution across the multiple runs of the search. Each restart begins at the best solution found so far, but reinitializes any search control parameters.
If this method is called multiple times, the restart schedule is not reinitialized, and the run lengths for the additional restarts will continue where the schedule left off.
- Specified by:
reoptimize
in interfaceReoptimizableMetaheuristic<T extends Copyable<T>>
- Parameters:
numRestarts
- The number of times to restart the metaheuristic.- Returns:
- The best end of run solution (and its cost) of this set of restarts,
which may or may not be the same as the solution contained
in this metaheuristic's
ProgressTracker
, which contains the best of all runs. Returns null if the run did not execute, such as if the ProgressTracker already contains the theoretical best solution.
-
split
public ReoptimizableMultistarter<T> 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 interfaceMetaheuristic<T extends Copyable<T>>
- Specified by:
split
in interfaceReoptimizableMetaheuristic<T extends Copyable<T>>
- Specified by:
split
in interfaceSplittable<T extends Copyable<T>>
- Overrides:
split
in classMultistarter<T extends Copyable<T>>
- 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.
-
-