Package org.apache.commons.rng.sampling.distribution

Class RejectionInversionZipfSampler

java.lang.Object

org.apache.commons.rng.sampling.distribution.SamplerBase

org.apache.commons.rng.sampling.distribution.RejectionInversionZipfSampler

All Implemented Interfaces:

DiscreteSampler, SharedStateDiscreteSampler, SharedStateSampler<SharedStateDiscreteSampler>

public class RejectionInversionZipfSampler
extends SamplerBase
implements SharedStateDiscreteSampler

Implementation of the Zipf distribution.

Sampling uses UniformRandomProvider.nextDouble().

Since:

1.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	RejectionInversionZipfSampler.RejectionInversionZipfSamplerImpl	Implements the rejection-inversion method for the Zipf distribution.

Field Summary

Fields

Modifier and Type	Field	Description
private final SharedStateDiscreteSampler	delegate	The implementation of the sample method.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	RejectionInversionZipfSampler(SharedStateDiscreteSampler delegate)	Private constructor used by to prevent partially initialized object if the construction of the delegate throws.
	RejectionInversionZipfSampler(UniformRandomProvider rng, int numberOfElements, double exponent)	This instance delegates sampling.

Method Summary

Modifier and Type	Method	Description
static SharedStateDiscreteSampler	of(UniformRandomProvider rng, int numberOfElements, double exponent)	Creates a new Zipf distribution sampler.
int	sample()	Rejection inversion sampling method for a discrete, bounded Zipf distribution that is based on the method described in Wolfgang Hörmann and Gerhard Derflinger.
String	toString()
SharedStateDiscreteSampler	withUniformRandomProvider(UniformRandomProvider rng)	Create a new instance of the sampler with the same underlying state using the given uniform random provider as the source of randomness.

Methods inherited from class org.apache.commons.rng.sampling.distribution.SamplerBase

nextDouble, nextInt, nextInt, nextLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.rng.sampling.distribution.DiscreteSampler

samples, samples

Field Details

delegate

private final SharedStateDiscreteSampler delegate

The implementation of the sample method.

Constructor Details

RejectionInversionZipfSampler

public RejectionInversionZipfSampler(UniformRandomProvider rng,
 int numberOfElements,
 double exponent)

This instance delegates sampling. Use the factory method of(UniformRandomProvider, int, double) to create an optimal sampler.

Parameters:

rng - Generator of uniformly distributed random numbers.

numberOfElements - Number of elements.

exponent - Exponent.

Throws:

IllegalArgumentException - if numberOfElements <= 0 or exponent < 0.

RejectionInversionZipfSampler

private RejectionInversionZipfSampler(SharedStateDiscreteSampler delegate)

Private constructor used by to prevent partially initialized object if the construction of the delegate throws. In future versions the public constructor should be removed.

Parameters:

delegate - Delegate.

Method Details

sample

public int sample()

Rejection inversion sampling method for a discrete, bounded Zipf distribution that is based on the method described in

Wolfgang Hörmann and Gerhard Derflinger. "Rejection-inversion to generate variates from monotone discrete distributions",
ACM Transactions on Modeling and Computer Simulation (TOMACS) 6.3 (1996): 169-184.

Specified by:

sample in interface DiscreteSampler

Returns:

a sample.

toString

public String toString()

Overrides:

toString in class SamplerBase

withUniformRandomProvider

public SharedStateDiscreteSampler withUniformRandomProvider(UniformRandomProvider rng)

Create a new instance of the sampler with the same underlying state using the given uniform random provider as the source of randomness.

Specified by:

withUniformRandomProvider in interface SharedStateSampler<SharedStateDiscreteSampler>

Parameters:

rng - Generator of uniformly distributed random numbers.

Returns:

the sampler

Since:

1.3

of

public static SharedStateDiscreteSampler of(UniformRandomProvider rng,
 int numberOfElements,
 double exponent)

Creates a new Zipf distribution sampler.

Note when exponent = 0 the Zipf distribution reduces to a discrete uniform distribution over the interval [1, n] with n the number of elements.

Parameters:

rng - Generator of uniformly distributed random numbers.

numberOfElements - Number of elements.

exponent - Exponent.

Returns:

the sampler

Throws:

IllegalArgumentException - if numberOfElements <= 0 or exponent < 0.

Since:

1.3