org.apache.commons.math3.distribution

## Class UniformIntegerDistribution

- java.lang.Object
- - org.apache.commons.math3.distribution.AbstractIntegerDistribution
  - - org.apache.commons.math3.distribution.UniformIntegerDistribution

All Implemented Interfaces:
  java.io.Serializable, IntegerDistribution

    public class UniformIntegerDistribution
    extends AbstractIntegerDistribution

Implementation of the uniform integer distribution.

Since:
  3.0
Version:
  $Id: UniformIntegerDistribution.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
  Uniform distribution (discrete), at Wikipedia, Serialized Form

### Field Summary

Fields
`private int` `lower` Lower bound (inclusive) of this distribution.
`private static long` `serialVersionUID` Serializable version identifier.
`private int` `upper` Upper bound (inclusive) of this distribution.

### Fields inherited from class org.apache.commons.math3.distribution.AbstractIntegerDistribution

`random, randomData`

### Constructor Summary

Constructors
Constructor and Description
`UniformIntegerDistribution(int lower, int upper)` Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).
`UniformIntegerDistribution(RandomGenerator rng, int lower, int upper)` Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).

### Method Summary

Methods
`double` `cumulativeProbability(int x)` For a random variable `X` whose values are distributed according to this distribution, this method returns `P(X <= x)`.
`double` `getNumericalMean()` Use this method to get the numerical value of the mean of this distribution.
`double` `getNumericalVariance()` Use this method to get the numerical value of the variance of this distribution.
`int` `getSupportLowerBound()` Access the lower bound of the support.
`int` `getSupportUpperBound()` Access the upper bound of the support.
`boolean` `isSupportConnected()` Use this method to get information about whether the support is connected, i.e.
`double` `probability(int x)` For a random variable `X` whose values are distributed according to this distribution, this method returns `P(X = x)`.
`int` `sample()` Generate a random value sampled from this distribution.

### Methods inherited from class org.apache.commons.math3.distribution.AbstractIntegerDistribution

`cumulativeProbability, inverseCumulativeProbability, reseedRandomGenerator, sample, solveInverseCumulativeProbability`

### Methods inherited from class java.lang.Object

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

### Field Detail

#### serialVersionUID

    private static final long serialVersionUID

Serializable version identifier.

See Also:
  Constant Field Values

#### lower

    private final int lower

Lower bound (inclusive) of this distribution.

#### upper

    private final int upper

Upper bound (inclusive) of this distribution.

### Constructor Detail

#### UniformIntegerDistribution

    public UniformIntegerDistribution(int lower,
                              int upper)
                               throws NumberIsTooLargeException

Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).

Parameters:
  `lower` - Lower bound (inclusive) of this distribution.
  `upper` - Upper bound (inclusive) of this distribution.
Throws:
  `NumberIsTooLargeException` - if `lower >= upper`.

#### UniformIntegerDistribution

    public UniformIntegerDistribution(RandomGenerator rng,
                              int lower,
                              int upper)
                               throws NumberIsTooLargeException

Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).

Parameters:
  `rng` - Random number generator.
  `lower` - Lower bound (inclusive) of this distribution.
  `upper` - Upper bound (inclusive) of this distribution.
Throws:
  `NumberIsTooLargeException` - if `lower >= upper`.
Since:
  3.1

### Method Detail

#### probability

    public double probability(int x)

For a random variable `X` whose values are distributed according to this distribution, this method returns `P(X = x)`. In other words, this method represents the probability mass function (PMF) for the distribution.

Parameters:
  `x` - the point at which the PMF is evaluated
Returns:
  the value of the probability mass function at `x`

#### cumulativeProbability

    public double cumulativeProbability(int x)

For a random variable `X` whose values are distributed according to this distribution, this method returns `P(X <= x)`. In other words, this method represents the (cumulative) distribution function (CDF) for this distribution.

Parameters:
  `x` - the point at which the CDF is evaluated
Returns:
  the probability that a random variable with this distribution takes a value less than or equal to `x`

#### getNumericalMean

    public double getNumericalMean()

Use this method to get the numerical value of the mean of this distribution. For lower bound `lower` and upper bound `upper`, the mean is `0.5 * (lower + upper)`.

Returns:
  the mean or `Double.NaN` if it is not defined

#### getNumericalVariance

    public double getNumericalVariance()

Use this method to get the numerical value of the variance of this distribution. For lower bound `lower` and upper bound `upper`, and `n = upper - lower + 1`, the variance is `(n^2 - 1) / 12`.

Returns:
  the variance (possibly `Double.POSITIVE_INFINITY` or `Double.NaN` if it is not defined)

#### getSupportLowerBound

    public int getSupportLowerBound()

Access the lower bound of the support. This method must return the same value as `inverseCumulativeProbability(0)`. In other words, this method must return

`inf {x in Z | P(X <= x) > 0}`.

The lower bound of the support is equal to the lower bound parameter of the distribution.

Returns:
  lower bound of the support

#### getSupportUpperBound

    public int getSupportUpperBound()

Access the upper bound of the support. This method must return the same value as `inverseCumulativeProbability(1)`. In other words, this method must return

`inf {x in R | P(X <= x) = 1}`.

The upper bound of the support is equal to the upper bound parameter of the distribution.

Returns:
  upper bound of the support

#### isSupportConnected

    public boolean isSupportConnected()

Use this method to get information about whether the support is connected, i.e. whether all integers between the lower and upper bound of the support are included in the support. The support of this distribution is connected.

Returns:
  `true`

#### sample

    public int sample()

Generate a random value sampled from this distribution. The default implementation uses the inversion method.

Specified by:
  `sample` in interface `IntegerDistribution`
Overrides:
  `sample` in class `AbstractIntegerDistribution`
Returns:
  a random value