
MOEA Framework 2.12 API Specification 

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java.lang.Object org.moeaframework.core.operator.real.PCX
public class PCX
Parentcentric crossover (PCX) operator. PCX is a multiparent operator, allowing a userdefined number of parents and offspring. Offspring are clustered around the parents, as depicted in the figure below.
References:
Constructor Summary  

PCX(int numberOfParents,
int numberOfOffspring)
Constructs a PCX operator with the specified number of parents and offspring. 

PCX(int numberOfParents,
int numberOfOffspring,
double eta,
double zeta)
Constructs a PCX operator with the specified number of parents and offspring, and the specified values for sigma_eta and
sigma_zeta . 
Method Summary  

Solution[] 
evolve(Solution[] parents)
Evolves one or more parent solutions (specified by getArity ) and
produces one or more child solutions. 
int 
getArity()
Returns the number of solutions that must be supplied to the evolve method. 
double 
getEta()
Returns the standard deviation of the normal distribution controlling the spread of solutions in the direction of the selected parent. 
int 
getNumberOfOffspring()
Returns the number of offspring produced by this operator. 
int 
getNumberOfParents()
Returns the number of parents required by this operator. 
double 
getZeta()
Returns the standard deviation of the normal distribution controlling the spread of solutions in the directions defined by the remaining parents. 
protected Solution 
pcx(Solution[] parents)
Returns one randomlygenerated offspring produced by this operator using parents[parents.length1] as the selected parent. 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Constructor Detail 

public PCX(int numberOfParents, int numberOfOffspring)
eta
and zeta
parameters are set to
0.1
, as suggested by Deb et al. (2002).
numberOfParents
 the number of parents required by this operatornumberOfOffspring
 the number of offspring produced by this
operatorpublic PCX(int numberOfParents, int numberOfOffspring, double eta, double zeta)
sigma_eta
and
sigma_zeta
.
numberOfParents
 the number of parents required by this operatornumberOfOffspring
 the number of offspring produced by this
operatoreta
 the standard deviation of the normal distribution controlling
the spread of solutions in the direction of the selected parentzeta
 the standard deviation of the normal distribution controlling
the spread of solutions in the directions defined by the remaining
parentsMethod Detail 

public int getNumberOfParents()
public int getNumberOfOffspring()
public double getEta()
public double getZeta()
public int getArity()
Variation
evolve
method.
getArity
in interface Variation
evolve
methodpublic Solution[] evolve(Solution[] parents)
Variation
getArity
) and
produces one or more child solutions. By contract, the parents must not
be modified. The copy constructor should be used to create copies of the
parents with these copies subsequently modified.
evolve
in interface Variation
parents
 the array of parent solutions
protected Solution pcx(Solution[] parents)
parents[parents.length1]
as the selected parent. Multiple
invocations of this method with the same argument will produce offspring
distributed about the selected parent.
parents
 the parent solutions
parents[parents.length1]
as the selected parent

MOEA Framework 2.12 API Specification 

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