RandomKey (Apache Commons Math 3.6.1 API)

java.lang.Object
- org.apache.commons.math3.genetics.Chromosome
- - org.apache.commons.math3.genetics.AbstractListChromosome<Double>
  - - org.apache.commons.math3.genetics.RandomKey<T>

Type Parameters:
T - type of the permuted objects

All Implemented Interfaces:

Comparable<Chromosome>, Fitness, PermutationChromosome<T>
```
public abstract class RandomKey<T>
extends AbstractListChromosome<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

Constructor Summary

Constructors
Constructor and Description

RandomKey(Double[] representation)
Constructor.

RandomKey(List<Double> representation)
Constructor.

Constructors
Constructor and Description
`RandomKey(Double[] representation)` Constructor.
`RandomKey(List<Double> representation)` Constructor.

Method Summary

Methods
Modifier and Type	Method and Description
`protected void`	`checkValidity(List<Double> chromosomeRepresentation)` Asserts that `representation` can represent a valid chromosome.
`static <S> List<Double>`	`comparatorPermutation(List<S> data, Comparator<S> comparator)` Generates a representation of a permutation corresponding to the `data` sorted by `comparator`.
`List<T>`	`decode(List<T> sequence)` Permutes the `sequence` of objects of type T according to the permutation this chromosome represents.
`static List<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> List<Double>`	`inducedPermutation(List<S> originalData, List<S> permutedData)` Generates a representation of a permutation corresponding to a permutation which yields `permutedData` when applied to `originalData`.
`protected boolean`	`isSame(Chromosome another)` Returns `true` iff `another` is a RandomKey and encodes the same permutation.
`static List<Double>`	`randomPermutation(int l)` Generates a representation corresponding to a random permutation of length l which can be passed to the RandomKey constructor.
`String`	`toString()`

Methods inherited from class org.apache.commons.math3.genetics.AbstractListChromosome
getLength, getRepresentation, newFixedLengthChromosome

Methods inherited from class org.apache.commons.math3.genetics.Chromosome
compareTo, findSameChromosome, getFitness, searchForFitnessUpdate

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.math3.genetics.Fitness
fitness

- Constructor Detail
  - RandomKey
```
public RandomKey(List<Double> representation)
          throws InvalidRepresentationException
```
    Constructor.
    
    Parameters:
    representation - list of [0,1] values representing the permutation
    
    Throws:
    
    InvalidRepresentationException - iff the representation can not represent a valid chromosome
  - RandomKey
```
public RandomKey(Double[] representation)
          throws InvalidRepresentationException
```
    Constructor.
    
    Parameters:
    representation - array of [0,1] values representing the permutation
    
    Throws:
    
    InvalidRepresentationException - iff the representation can not represent a valid chromosome
- Method Detail
  - decode
```
public List<T> decode(List<T> sequence)
```
    Permutes the sequence 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 interface PermutationChromosome<T>
    
    Parameters:
    sequence - the unpermuted (original) sequence of objects
    
    Returns:
    permutation of sequence represented by this permutation
  - isSame
```
protected boolean isSame(Chromosome another)
```
    Returns true iff another is a RandomKey and encodes the same permutation.
    
    Overrides:
    
    isSame in class Chromosome
    
    Parameters:
    another - chromosome to compare
    
    Returns:
    true iff chromosomes encode the same permutation
  - checkValidity
```
protected void checkValidity(List<Double> chromosomeRepresentation)
                      throws InvalidRepresentationException
```
    Asserts that representation can represent a valid chromosome.
    
    Specified by:
    
    checkValidity in class AbstractListChromosome<Double>
    
    Parameters:
    chromosomeRepresentation - representation of the chromosome
    
    Throws:
    
    InvalidRepresentationException - iff the representation can not represent a valid chromosome
  - randomPermutation
```
public static final List<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
  - identityPermutation
```
public static final List<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
  - comparatorPermutation
```
public static <S> List<Double> comparatorPermutation(List<S> data,
                                     Comparator<S> comparator)
```
    Generates a representation of a permutation corresponding to the data sorted by comparator. The data 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 order
    comparator - how the data will be compared
    
    Returns:
    list representation of the permutation corresponding to the parameters
  - inducedPermutation
```
public static <S> List<Double> inducedPermutation(List<S> originalData,
                                  List<S> permutedData)
                                       throws DimensionMismatchException,
                                              MathIllegalArgumentException
```
    Generates a representation of a permutation corresponding to a permutation which yields permutedData when applied to originalData. This method can be viewed as an inverse to decode(List).
    
    Type Parameters:
    S - type of the data
    Parameters:
    originalData - the original, unpermuted data
    permutedData - the data, somehow permuted
    
    Returns:
    representation of a permutation corresponding to the permutation originalData -> permutedData
    
    Throws:
    
    DimensionMismatchException - iff the length of originalData and permutedData lists are not equal
    
    MathIllegalArgumentException - iff the permutedData and originalData lists contain different data
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class AbstractListChromosome<Double>

Class RandomKey<T>

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.math3.genetics.AbstractListChromosome

Methods inherited from class org.apache.commons.math3.genetics.Chromosome

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.commons.math3.genetics.Fitness

Constructor Detail

RandomKey

RandomKey

Method Detail

decode

isSame

checkValidity

randomPermutation

identityPermutation

comparatorPermutation

inducedPermutation

toString