eaLib API Docs
Last Modified : January 7 2002

mss.ea.sel
Class TruncationSelection

java.lang.Object
  |
  +--mss.ea.core.GeneticOperator
        |
        +--mss.ea.sel.Selection
              |
              +--mss.ea.sel.TruncationSelection
All Implemented Interfaces:
SingleStreamProcessor, StreamProcessor
Direct Known Subclasses:
FitnessTruncationSelection, PercentageTruncationSelection, RankingTruncationSelection, ScoreTruncationSelection

public abstract class TruncationSelection
extends Selection

Abstract base class for a truncation selection. A truncation selection only selects individuals, which have got an attribute above a particular threshold. The threshold can be percentage value, the score or a fitness value. Individuals below the threshold have got the selection probability of 0. Individuals above are selected randomly.

Since:
0.1
Version:
0.1 (08-15-2001)
Author:
Andreas Rummler

Field Summary
protected  java.util.Random rand
          Random generator.
 
Fields inherited from class mss.ea.sel.Selection
multSelection, numberPerSelection
 
Fields inherited from class mss.ea.core.GeneticOperator
description, ID, name
 
Constructor Summary
TruncationSelection(int numberPerSelection)
          Constructor with number per selection.
TruncationSelection(int numberPerSelection, boolean allowMultipleSelection)
          Constructor number per selection and multiple selection flag.
 
Method Summary
protected abstract  int getThresholdIndex(IndividualStream is)
           
 IndividualStream select(IndividualStream is)
          Abstract select method.
 
Methods inherited from class mss.ea.sel.Selection
getSelectionSize, process, setSelectionSize
 
Methods inherited from class mss.ea.core.GeneticOperator
getDescription, getID, getName, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface mss.ea.core.StreamProcessor
getName
 

Field Detail

rand

protected java.util.Random rand
Random generator.
Constructor Detail

TruncationSelection

public TruncationSelection(int numberPerSelection)
Constructor with number per selection.
Parameters:
numberPerSelection - number how many individuals are selected

TruncationSelection

public TruncationSelection(int numberPerSelection,
                           boolean allowMultipleSelection)
Constructor number per selection and multiple selection flag.
Parameters:
numberPerSelection - number how many individuals are selected
allowMultipleSelection - state of the multiple selection flag
Method Detail

select

public IndividualStream select(IndividualStream is)
Description copied from class: Selection
Abstract select method. Selects individuals. This method depends on the kind of the selection operator and must be implemented by each subclass. It should be discussed, if this method should be protected.
Overrides:
select in class Selection
Following copied from class: mss.ea.sel.Selection
Parameters:
is - stream of individuals to select from
Returns:
stream of selected individuals
Throws:
SelectionException - thrown in case the selection mechanism fails

getThresholdIndex

protected abstract int getThresholdIndex(IndividualStream is)

eaLib API Docs
Last Modified : January 7 2002

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