Package org.apache.commons.math4.legacy.distribution

Class AbstractIntegerDistribution

java.lang.Object

org.apache.commons.math4.legacy.distribution.AbstractIntegerDistribution

All Implemented Interfaces:

org.apache.commons.statistics.distribution.DiscreteDistribution

Direct Known Subclasses:

EnumeratedIntegerDistribution

public abstract class AbstractIntegerDistribution
extends Object
implements org.apache.commons.statistics.distribution.DiscreteDistribution

Base class for integer-valued discrete distributions. Default implementations are provided for some of the methods that do not vary from distribution to distribution.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.commons.statistics.distribution.DiscreteDistribution

org.apache.commons.statistics.distribution.DiscreteDistribution.Sampler

Constructor Summary

Constructors

Constructor	Description
AbstractIntegerDistribution()

Method Summary

Modifier and Type	Method	Description
org.apache.commons.statistics.distribution.DiscreteDistribution.Sampler	createSampler(org.apache.commons.rng.UniformRandomProvider rng)
int	inverseCumulativeProbability(double p)	The default implementation returns DiscreteDistribution.getSupportLowerBound() for p = 0, DiscreteDistribution.getSupportUpperBound() for p = 1, and solveInverseCumulativeProbability(double, int, int) for 0 < p < 1.
double	logProbability(int x)
double	probability(int x0, int x1)	The default implementation uses the identity
static int[]	sample(int n, org.apache.commons.statistics.distribution.DiscreteDistribution.Sampler sampler)	Utility function for allocating an array and filling it with n samples generated by the given sampler.
protected int	solveInverseCumulativeProbability(double p, int lower, int upper)	This is a utility function used by inverseCumulativeProbability(double).

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.statistics.distribution.DiscreteDistribution

cumulativeProbability, getMean, getSupportLowerBound, getSupportUpperBound, getVariance, inverseSurvivalProbability, probability, survivalProbability

Constructor Detail

AbstractIntegerDistribution

public AbstractIntegerDistribution()

Method Detail

probability

public double probability(int x0,
                          int x1)
                   throws NumberIsTooLargeException

The default implementation uses the identity

P(x0 < X <= x1) = P(X <= x1) - P(X <= x0)

Specified by:

probability in interface org.apache.commons.statistics.distribution.DiscreteDistribution

Throws:

NumberIsTooLargeException

Since:

4.0, was previously named cumulativeProbability

inverseCumulativeProbability

public int inverseCumulativeProbability(double p)
                                 throws OutOfRangeException

The default implementation returns

• DiscreteDistribution.getSupportLowerBound() for p = 0,
• DiscreteDistribution.getSupportUpperBound() for p = 1, and
• solveInverseCumulativeProbability(double, int, int) for 0 < p < 1.

Specified by:

inverseCumulativeProbability in interface org.apache.commons.statistics.distribution.DiscreteDistribution

Throws:

OutOfRangeException

solveInverseCumulativeProbability

protected int solveInverseCumulativeProbability(double p,
                                                int lower,
                                                int upper)

This is a utility function used by inverseCumulativeProbability(double). It assumes 0 < p < 1 and that the inverse cumulative probability lies in the bracket (lower, upper]. The implementation does simple bisection to find the smallest p-quantile inf{x in Z | P(X<=x) >= p}.

Parameters:

p - the cumulative probability

lower - a value satisfying cumulativeProbability(lower) < p

upper - a value satisfying p <= cumulativeProbability(upper)

Returns:

the smallest p-quantile of this distribution

logProbability

public double logProbability(int x)

The default implementation simply computes the logarithm of probability(x).

Specified by:

logProbability in interface org.apache.commons.statistics.distribution.DiscreteDistribution

sample

public static int[] sample(int n,
                           org.apache.commons.statistics.distribution.DiscreteDistribution.Sampler sampler)

Utility function for allocating an array and filling it with n samples generated by the given sampler.

Parameters:

n - Number of samples.

sampler - Sampler.

Returns:

an array of size n.

createSampler

public org.apache.commons.statistics.distribution.DiscreteDistribution.Sampler createSampler(org.apache.commons.rng.UniformRandomProvider rng)

Specified by:

createSampler in interface org.apache.commons.statistics.distribution.DiscreteDistribution