Class FastLoadedDiceRollerDiscreteSampler.FLDRSampler

java.lang.Object

org.apache.commons.rng.sampling.distribution.FastLoadedDiceRollerDiscreteSampler

org.apache.commons.rng.sampling.distribution.FastLoadedDiceRollerDiscreteSampler.FLDRSampler

All Implemented Interfaces:

DiscreteSampler, SharedStateDiscreteSampler, SharedStateSampler<SharedStateDiscreteSampler>

Enclosing class:

FastLoadedDiceRollerDiscreteSampler

private static final class FastLoadedDiceRollerDiscreteSampler.FLDRSampler
extends FastLoadedDiceRollerDiscreteSampler

Class to implement the FLDR sample algorithm.

Since:

1.5

Field Summary

Fields

Modifier and Type	Field	Description
private int	booleanSource	Provides a bit source for booleans.
private static final int	EMPTY_BOOL_SOURCE	Empty boolean source.
private final int[]	h	Number of leaf nodes at each level.
private final int	k	Number of levels in the discrete distribution generating (DDG) tree.
private final int[]	lH	Stores the leaf node labels in increasing order.
private final int	n	Number of categories.
private final UniformRandomProvider	rng	Underlying source of randomness.

Constructor Summary

Constructors

Modifier	Constructor	Description
(package private)	FLDRSampler(UniformRandomProvider rng, int n, int k, int[] h, int[] lH)	Creates a sampler.
private	FLDRSampler(UniformRandomProvider rng, FastLoadedDiceRollerDiscreteSampler.FLDRSampler source)	Creates a copy with a new source of randomness.

Method Summary

Modifier and Type	Method	Description
private int	flip()	Provides a source of boolean bits.
int	sample()	Creates an int sample.
String	toString()
FastLoadedDiceRollerDiscreteSampler	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 FastLoadedDiceRollerDiscreteSampler

checkArraySize, indexOfNonZero, of, of, of

Methods inherited from class Object

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

Methods inherited from interface DiscreteSampler

samples, samples

Field Details

EMPTY_BOOL_SOURCE

private static final int EMPTY_BOOL_SOURCE

Empty boolean source. This is the location of the sign-bit after 31 right shifts on the boolean source.

See Also:

• Constant Field Values

rng

private final UniformRandomProvider rng

Underlying source of randomness.

n

private final int n

Number of categories.

k

private final int k

Number of levels in the discrete distribution generating (DDG) tree. Equal to ceil(log2(m)) where m is the sum of observations.

h

private final int[] h

Number of leaf nodes at each level.

lH

private final int[] lH

Stores the leaf node labels in increasing order. Named H in the FLDR paper.

booleanSource

private int booleanSource

Provides a bit source for booleans.

A cached value from a call to UniformRandomProvider.nextInt().

Only stores 31-bits when full as 1 bit has already been consumed. The sign bit is a flag that shifts down so the source eventually equals 1 when all bits are consumed and will trigger a refill.

Constructor Details

FLDRSampler

FLDRSampler(UniformRandomProvider rng,
 int n,
 int k,
 int[] h,
 int[] lH)

Creates a sampler.

The input parameters are not validated and must be correctly computed tables.

Parameters:

rng - Generator of uniformly distributed random numbers.

n - Number of categories

k - Number of levels in the discrete distribution generating (DDG) tree. Equal to ceil(log2(m)) where m is the sum of observations.

h - Number of leaf nodes at each level.

lH - Stores the leaf node labels in increasing order.

FLDRSampler

private FLDRSampler(UniformRandomProvider rng,
 FastLoadedDiceRollerDiscreteSampler.FLDRSampler source)

Creates a copy with a new source of randomness.

Parameters:

rng - Generator of uniformly distributed random numbers.

source - Source to copy.

Method Details

sample

public int sample()

Creates an int sample.

Returns:

a sample.

flip

private int flip()

Provides a source of boolean bits.

Note: This replicates the boolean cache functionality of o.a.c.rng.core.source32.IntProvider. The method has been simplified to return an int value rather than a boolean.

Returns:

the bit (0 or 1)

toString

public String toString()

Overrides:

toString in class Object

withUniformRandomProvider

public FastLoadedDiceRollerDiscreteSampler 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>

Specified by:

withUniformRandomProvider in class FastLoadedDiceRollerDiscreteSampler

Parameters:

rng - Generator of uniformly distributed random numbers.

Returns:

the sampler