Class DiscreteUniformSampler.SmallRangeDiscreteUniformSampler

java.lang.Object

org.apache.commons.rng.sampling.distribution.DiscreteUniformSampler.AbstractDiscreteUniformSampler

org.apache.commons.rng.sampling.distribution.DiscreteUniformSampler.SmallRangeDiscreteUniformSampler

All Implemented Interfaces:

DiscreteSampler, SharedStateDiscreteSampler, SharedStateSampler<SharedStateDiscreteSampler>

Enclosing class:

DiscreteUniformSampler

private static final class DiscreteUniformSampler.SmallRangeDiscreteUniformSampler
extends DiscreteUniformSampler.AbstractDiscreteUniformSampler

Discrete uniform distribution sampler when the range is small enough to fit in a positive integer. This sampler assumes the lower bound of the range is 0.

Implements the algorithm of Lemire (2019).

Since:

1.0

See Also:

• Fast Random Integer Generation in an Interval

Field Summary

Fields

Modifier and Type	Field	Description
private final long	n	Maximum range of the sample (exclusive).
private final long	threshold	The level below which samples are rejected based on the fraction remainder.

Fields inherited from class DiscreteUniformSampler.AbstractDiscreteUniformSampler

rng

Constructor Summary

Constructors

Constructor	Description
SmallRangeDiscreteUniformSampler(UniformRandomProvider rng, int range)
SmallRangeDiscreteUniformSampler(UniformRandomProvider rng, DiscreteUniformSampler.SmallRangeDiscreteUniformSampler source)

Method Summary

Modifier and Type	Method	Description
int	sample()	Creates an int sample.
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 DiscreteUniformSampler.AbstractDiscreteUniformSampler

toString

Methods inherited from class Object

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

Methods inherited from interface DiscreteSampler

samples, samples

Field Details

n

private final long n

Maximum range of the sample (exclusive).

threshold

private final long threshold

The level below which samples are rejected based on the fraction remainder.

Any remainder below this denotes that there are still floor(2^32 / n) more observations of this sample from the interval [0, 2^32), where n is the range.

Constructor Details

SmallRangeDiscreteUniformSampler

SmallRangeDiscreteUniformSampler(UniformRandomProvider rng,
 int range)

Parameters:

rng - Generator of uniformly distributed random numbers.

range - Maximum range of the sample (exclusive).

SmallRangeDiscreteUniformSampler

SmallRangeDiscreteUniformSampler(UniformRandomProvider rng,
 DiscreteUniformSampler.SmallRangeDiscreteUniformSampler source)

Parameters:

rng - Generator of uniformly distributed random numbers.

source - Source to copy.

Method Details

sample

public int sample()

Description copied from interface: DiscreteSampler

Creates an int sample.

Returns:

a sample.

withUniformRandomProvider

public SharedStateDiscreteSampler withUniformRandomProvider(UniformRandomProvider rng)

Description copied from interface: SharedStateSampler

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

Parameters:

rng - Generator of uniformly distributed random numbers.

Returns:

the sampler