Package org.apache.commons.math.genetics
Class RandomKey<T>
- java.lang.Object
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- org.apache.commons.math.genetics.Chromosome
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- org.apache.commons.math.genetics.AbstractListChromosome<java.lang.Double>
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- org.apache.commons.math.genetics.RandomKey<T>
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- Type Parameters:
T
- type of the permuted objects
- All Implemented Interfaces:
java.lang.Comparable<Chromosome>
,Fitness
,PermutationChromosome<T>
public abstract class RandomKey<T> extends AbstractListChromosome<java.lang.Double> implements PermutationChromosome<T>
Random Key chromosome is used for permutation representation. It is a vector of a fixed length of real numbers in [0,1] interval. The index of the i-th smallest value in the vector represents an i-th member of the permutation.
For example, the random key [0.2, 0.3, 0.8, 0.1] corresponds to the permutation of indices (3,0,1,2). If the original (unpermuted) sequence would be (a,b,c,d), this would mean the sequence (d,a,b,c).
With this representation, common operators like n-point crossover can be used, because any such chromosome represents a valid permutation.
Since the chromosome (and thus its arrayRepresentation) is immutable, the array representation is sorted only once in the constructor.
For details, see:
- Bean, J.C.: Genetic algorithms and random keys for sequencing and optimization. ORSA Journal on Computing 6 (1994) 154–160
- Rothlauf, F.: Representations for Genetic and Evolutionary Algorithms. Volume 104 of Studies in Fuzziness and Soft Computing. Physica-Verlag, Heidelberg (2002)
- Since:
- 2.0
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static <S> java.util.List<java.lang.Double>
comparatorPermutation(java.util.List<S> data, java.util.Comparator<S> comparator)
Generates a representation of a permutation corresponding to thedata
sorted bycomparator
.java.util.List<T>
decode(java.util.List<T> sequence)
Permutes thesequence
of objects of type T according to the permutation this chromosome represents.static java.util.List<java.lang.Double>
identityPermutation(int l)
Generates a representation corresponding to an identity permutation of length l which can be passed to the RandomKey constructor.static <S> java.util.List<java.lang.Double>
inducedPermutation(java.util.List<S> originalData, java.util.List<S> permutedData)
Generates a representation of a permutation corresponding to a permutation which yieldspermutedData
when applied tooriginalData
.static java.util.List<java.lang.Double>
randomPermutation(int l)
Generates a representation corresponding to a random permutation of length l which can be passed to the RandomKey constructor.java.lang.String
toString()
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Methods inherited from class org.apache.commons.math.genetics.AbstractListChromosome
getLength, newFixedLengthChromosome
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Methods inherited from class org.apache.commons.math.genetics.Chromosome
compareTo, getFitness, searchForFitnessUpdate
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Constructor Detail
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RandomKey
public RandomKey(java.util.List<java.lang.Double> representation)
Constructor.- Parameters:
representation
- list of [0,1] values representing the permutation
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RandomKey
public RandomKey(java.lang.Double[] representation)
Constructor.- Parameters:
representation
- array of [0,1] values representing the permutation
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Method Detail
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decode
public java.util.List<T> decode(java.util.List<T> sequence)
Permutes thesequence
of objects of type T according to the permutation this chromosome represents. For example, if this chromosome represents a permutation (3,0,1,2), and the unpermuted sequence is (a,b,c,d), this yields (d,a,b,c).- Specified by:
decode
in interfacePermutationChromosome<T>
- Parameters:
sequence
- the unpermuted (original) sequence of objects- Returns:
- permutation of
sequence
represented by this permutation
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randomPermutation
public static final java.util.List<java.lang.Double> randomPermutation(int l)
Generates a representation corresponding to a random permutation of length l which can be passed to the RandomKey constructor.- Parameters:
l
- length of the permutation- Returns:
- representation of a random permutation
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identityPermutation
public static final java.util.List<java.lang.Double> identityPermutation(int l)
Generates a representation corresponding to an identity permutation of length l which can be passed to the RandomKey constructor.- Parameters:
l
- length of the permutation- Returns:
- representation of an identity permutation
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comparatorPermutation
public static <S> java.util.List<java.lang.Double> comparatorPermutation(java.util.List<S> data, java.util.Comparator<S> comparator)
Generates a representation of a permutation corresponding to thedata
sorted bycomparator
. Thedata
is not modified during the process. This is useful if you want to inject some permutations to the initial population.- Type Parameters:
S
- type of the data- Parameters:
data
- list of data determining the ordercomparator
- how the data will be compared- Returns:
- list representation of the permutation corresponding to the parameters
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inducedPermutation
public static <S> java.util.List<java.lang.Double> inducedPermutation(java.util.List<S> originalData, java.util.List<S> permutedData) throws java.lang.IllegalArgumentException
Generates a representation of a permutation corresponding to a permutation which yieldspermutedData
when applied tooriginalData
. This method can be viewed as an inverse todecode(List)
.- Type Parameters:
S
- type of the data- Parameters:
originalData
- the original, unpermuted datapermutedData
- the data, somehow permuted- Returns:
- representation of a permutation corresponding to the permutation
originalData -> permutedData
- Throws:
java.lang.IllegalArgumentException
- iff thepermutedData
andoriginalData
contains different data
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toString
public java.lang.String toString()
- Overrides:
toString
in classAbstractListChromosome<java.lang.Double>
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