Class CompositeSamplers

java.lang.Object

org.apache.commons.rng.sampling.CompositeSamplers

public final class CompositeSamplers
extends Object

Factory class to create a sampler that combines sampling from multiple samplers.

The composite sampler is constructed using a builder for the type of samplers that will form the composite. Each sampler has a weight in the composition. Samples are returned using a 2 step algorithm:

1. Select a sampler based on its weighting
2. Return a sample from the selected sampler

The weights used for each sampler create a discrete probability distribution. This is sampled using a discrete probability distribution sampler. The builder provides methods to change the default implementation.

The following example will create a sampler to uniformly sample the border of a triangle using the line segment lengths as weights:

UniformRandomProvider rng = RandomSource.KISS.create();
double[] a = {1.23, 4.56};
double[] b = {6.78, 9.01};
double[] c = {3.45, 2.34};
ObjectSampler<double[]> sampler =
    CompositeSamplers.<double[]>newObjectSamplerBuilder()
        .add(LineSampler.of(rng, a, b), Math.hypot(a[0] - b[0], a[1] - b[1]))
        .add(LineSampler.of(rng, b, c), Math.hypot(b[0] - c[0], b[1] - c[1]))
        .add(LineSampler.of(rng, c, a), Math.hypot(c[0] - a[0], c[1] - a[1]))
        .build(rng);

Since:

1.4

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	CompositeSamplers.Builder<S>	Builds a composite sampler.
private static class	CompositeSamplers.CompositeSampler<S>	A composite sampler.
private static final class	CompositeSamplers.ContinuousSamplerFactory	A factory for creating a composite ContinuousSampler.
static enum	CompositeSamplers.DiscreteProbabilitySampler	The DiscreteProbabilitySampler class defines implementations that sample from a user-defined discrete probability distribution.
static interface	CompositeSamplers.DiscreteProbabilitySamplerFactory	A factory for creating a sampler of a user-defined discrete probability distribution.
private static final class	CompositeSamplers.DiscreteSamplerFactory	A factory for creating a composite DiscreteSampler.
private static final class	CompositeSamplers.LongSamplerFactory	A factory for creating a composite LongSampler.
private static final class	CompositeSamplers.ObjectSamplerFactory<T>	A factory for creating a composite ObjectSampler.
private static final class	CompositeSamplers.SamplerBuilder<S>	Builds a composite sampler.
private static final class	CompositeSamplers.SharedStateContinuousSamplerFactory	A factory for creating a composite SharedStateContinuousSampler.
private static final class	CompositeSamplers.SharedStateDiscreteProbabilitySampler	A class to implement the SharedStateDiscreteSampler interface for a discrete probability sampler given a factory and the probability distribution.
private static final class	CompositeSamplers.SharedStateDiscreteSamplerFactory	A factory for creating a composite SharedStateDiscreteSampler.
private static final class	CompositeSamplers.SharedStateLongSamplerFactory	A factory for creating a composite SharedStateLongSampler.
private static final class	CompositeSamplers.SharedStateObjectSamplerFactory<T>	A factory for creating a composite SharedStateObjectSampler.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	CompositeSamplers()	No public instances.

Method Summary

Modifier and Type	Method	Description
private static <T extends SharedStateSampler<T>> List<T>	copy(List<T> samplers, UniformRandomProvider rng)	Create a copy instance of each sampler in the list of samplers using the given uniform random provider as the source of randomness.
static CompositeSamplers.Builder<ContinuousSampler>	newContinuousSamplerBuilder()	Create a new builder for a composite ContinuousSampler.
static CompositeSamplers.Builder<DiscreteSampler>	newDiscreteSamplerBuilder()	Create a new builder for a composite DiscreteSampler.
static CompositeSamplers.Builder<LongSampler>	newLongSamplerBuilder()	Create a new builder for a composite LongSampler.
static <T> CompositeSamplers.Builder<ObjectSampler<T>>	newObjectSamplerBuilder()	Create a new builder for a composite ObjectSampler.
static CompositeSamplers.Builder<SharedStateContinuousSampler>	newSharedStateContinuousSamplerBuilder()	Create a new builder for a composite SharedStateContinuousSampler.
static CompositeSamplers.Builder<SharedStateDiscreteSampler>	newSharedStateDiscreteSamplerBuilder()	Create a new builder for a composite SharedStateDiscreteSampler.
static CompositeSamplers.Builder<SharedStateLongSampler>	newSharedStateLongSamplerBuilder()	Create a new builder for a composite SharedStateLongSampler.
static <T> CompositeSamplers.Builder<SharedStateObjectSampler<T>>	newSharedStateObjectSamplerBuilder()	Create a new builder for a composite SharedStateObjectSampler.

Methods inherited from class Object

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

Constructor Details

CompositeSamplers

private CompositeSamplers()

No public instances.

Method Details

newObjectSamplerBuilder

public static <T>
CompositeSamplers.Builder<ObjectSampler<T>> newObjectSamplerBuilder()

Create a new builder for a composite ObjectSampler.

Note: If the compiler cannot infer the type parameter of the sampler it can be specified within the diamond operator <T> preceding the call to newObjectSamplerBuilder(), for example:

CompositeSamplers.<double[]>newObjectSamplerBuilder()

Type Parameters:

T - Type of the sample.

Returns:

the builder

newSharedStateObjectSamplerBuilder

public static <T>
CompositeSamplers.Builder<SharedStateObjectSampler<T>> newSharedStateObjectSamplerBuilder()

Create a new builder for a composite SharedStateObjectSampler.

Note: If the compiler cannot infer the type parameter of the sampler it can be specified within the diamond operator <T> preceding the call to newSharedStateObjectSamplerBuilder(), for example:

CompositeSamplers.<double[]>newSharedStateObjectSamplerBuilder()

Type Parameters:

T - Type of the sample.

Returns:

the builder

newDiscreteSamplerBuilder

public static CompositeSamplers.Builder<DiscreteSampler> newDiscreteSamplerBuilder()

Create a new builder for a composite DiscreteSampler.

Returns:

the builder

newSharedStateDiscreteSamplerBuilder

public static CompositeSamplers.Builder<SharedStateDiscreteSampler> newSharedStateDiscreteSamplerBuilder()

Create a new builder for a composite SharedStateDiscreteSampler.

Returns:

the builder

newContinuousSamplerBuilder

public static CompositeSamplers.Builder<ContinuousSampler> newContinuousSamplerBuilder()

Create a new builder for a composite ContinuousSampler.

Returns:

the builder

newSharedStateContinuousSamplerBuilder

public static CompositeSamplers.Builder<SharedStateContinuousSampler> newSharedStateContinuousSamplerBuilder()

Create a new builder for a composite SharedStateContinuousSampler.

Returns:

the builder

newLongSamplerBuilder

public static CompositeSamplers.Builder<LongSampler> newLongSamplerBuilder()

Create a new builder for a composite LongSampler.

Returns:

the builder

newSharedStateLongSamplerBuilder

public static CompositeSamplers.Builder<SharedStateLongSampler> newSharedStateLongSamplerBuilder()

Create a new builder for a composite SharedStateLongSampler.

Returns:

the builder

copy

private static <T extends SharedStateSampler<T>>
List<T> copy(List<T> samplers,
 UniformRandomProvider rng)

Create a copy instance of each sampler in the list of samplers using the given uniform random provider as the source of randomness.

Type Parameters:

T - the type of sampler

Parameters:

samplers - Source to copy.

rng - Generator of uniformly distributed random numbers.

Returns:

the copy