org.hipparchus.random

Class RandomDataGenerator

java.lang.Object

org.hipparchus.random.RandomDataGenerator

All Implemented Interfaces:

Serializable, RandomGenerator

public class RandomDataGenerator
extends Object
implements RandomGenerator, Serializable

A class for generating random data.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RandomDataGenerator() Construct a RandomDataGenerator with a default RandomGenerator as its source of random data.
RandomDataGenerator(long seed) Construct a RandomDataGenerator with a default RandomGenerator as its source of random data, initialized with the given seed value.

Method Summary

Modifier and Type	Method and Description
protected RandomGenerator	delegate() Returns the backing delegate instance that methods are forwarded to.
double	nextBeta(double alpha, double beta) Returns the next pseudo-random beta-distributed value with the given shape and scale parameters.
boolean	nextBoolean() Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
void	nextBytes(byte[] bytes) Generates random bytes and places them into a user-supplied byte array.
void	nextBytes(byte[] bytes, int offset, int length) Generates random bytes and places them into a user-supplied byte array.
int	nextDeviate(IntegerDistribution dist) Returns a random deviate from the given distribution.
double	nextDeviate(RealDistribution dist) Returns a random deviate from the given distribution.
int[]	nextDeviates(IntegerDistribution dist, int size) Returns an array of random deviates from the given distribution.
double[]	nextDeviates(RealDistribution dist, int size) Returns an array of random deviates from the given distribution.
double	nextDouble() Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
double	nextExponential(double mean) Returns the next pseudo-random, exponentially distributed deviate.
float	nextFloat() Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
double	nextGamma(double shape, double scale) Returns the next pseudo-random gamma-distributed value with the given shape and scale parameters.
double	nextGaussian() Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
String	nextHexString(int len) Generates a random string of hex characters of length len.
int	nextInt() Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.
int	nextInt(int n) Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
int	nextInt(int lower, int upper) Returns a uniformly distributed random integer between lower and upper (inclusive).
double	nextLogNormal(double shape, double scale) Returns the next log-normally-distributed pseudo-random deviate.
long	nextLong() Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
long	nextLong(long n) Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
long	nextLong(long lower, long upper) Returns a uniformly distributed random long integer between lower and upper (inclusive).
double	nextNormal(double mean, double standardDeviation) Returns the next normally-distributed pseudo-random deviate.
int[]	nextPermutation(int n, int k) Generates an integer array of length k whose entries are selected randomly, without repetition, from the integers 0, ..., n - 1 (inclusive).
int	nextPoisson(double mean) Returns a poisson-distributed deviate with the given mean.
Object[]	nextSample(Collection<?> c, int k) Returns an array of k objects selected randomly from the Collection c.
double[]	nextSample(double[] a, int k) Returns an array of k double values selected randomly from the double array a.
double	nextUniform(double lower, double upper) Returns a double value uniformly distributed over [lower, upper]
int	nextZipf(int numberOfElements, double exponent) Returns an integer value following a Zipf distribution with the given parameter.
static RandomDataGenerator	of(RandomGenerator randomGenerator) Factory method to create a RandomData instance using the supplied RandomGenerator.
void	setSeed(int seed) Sets the seed of the underlying random number generator using an int seed.
void	setSeed(int[] seed) Sets the seed of the underlying random number generator using an int array seed.
void	setSeed(long seed) Sets the seed of the underlying random number generator using a long seed.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.hipparchus.random.RandomGenerator

nextBoolean, nextBytes, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong, nextLong, setSeed, setSeed, setSeed

Constructor Detail

RandomDataGenerator

public RandomDataGenerator()

Construct a RandomDataGenerator with a default RandomGenerator as its source of random data.

RandomDataGenerator

public RandomDataGenerator(long seed)

Construct a RandomDataGenerator with a default RandomGenerator as its source of random data, initialized with the given seed value.

Parameters:

seed - seed value

Method Detail

of

public static RandomDataGenerator of(RandomGenerator randomGenerator)

Factory method to create a RandomData instance using the supplied RandomGenerator.

Parameters:

randomGenerator - source of random bits

Returns:

a RandomData using the given RandomGenerator to source bits

Throws:

MathIllegalArgumentException - if randomGenerator is null

delegate

protected RandomGenerator delegate()

Returns the backing delegate instance that methods are forwarded to.

Concrete subclasses override this method to supply the instance being decorated.

Returns:

the delegate instance

nextBeta

public double nextBeta(double alpha,
                       double beta)

Returns the next pseudo-random beta-distributed value with the given shape and scale parameters.

Parameters:

alpha - First shape parameter (must be positive).

beta - Second shape parameter (must be positive).

Returns:

beta-distributed random deviate

nextExponential

public double nextExponential(double mean)

Returns the next pseudo-random, exponentially distributed deviate.

Parameters:

mean - mean of the exponential distribution

Returns:

exponentially distributed deviate about the given mean

nextGamma

public double nextGamma(double shape,
                        double scale)

Returns the next pseudo-random gamma-distributed value with the given shape and scale parameters.

Parameters:

shape - shape parameter of the distribution

scale - scale parameter of the distribution

Returns:

gamma-distributed random deviate

nextNormal

public double nextNormal(double mean,
                         double standardDeviation)

Returns the next normally-distributed pseudo-random deviate.

Parameters:

mean - mean of the normal distribution

standardDeviation - standard deviation of the normal distribution

Returns:

a random value, normally distributed with the given mean and standard deviation

nextLogNormal

public double nextLogNormal(double shape,
                            double scale)

Returns the next log-normally-distributed pseudo-random deviate.

Parameters:

shape - shape parameter of the log-normal distribution

scale - scale parameter of the log-normal distribution

Returns:

a random value, normally distributed with the given mean and standard deviation

nextPoisson

public int nextPoisson(double mean)

Returns a poisson-distributed deviate with the given mean.

Parameters:

mean - expected value

Returns:

poisson deviate

Throws:

MathIllegalArgumentException - if mean is not strictly positive

nextDeviate

public double nextDeviate(RealDistribution dist)

Returns a random deviate from the given distribution.

Parameters:

dist - the distribution to sample from

Returns:

a random value following the given distribution

nextDeviates

public double[] nextDeviates(RealDistribution dist,
                             int size)

Returns an array of random deviates from the given distribution.

Parameters:

dist - the distribution to sample from

size - the number of values to return

Returns:

an array of size values following the given distribution

nextDeviate

public int nextDeviate(IntegerDistribution dist)

Returns a random deviate from the given distribution.

Parameters:

dist - the distribution to sample from

Returns:

a random value following the given distribution

nextDeviates

public int[] nextDeviates(IntegerDistribution dist,
                          int size)

Returns an array of random deviates from the given distribution.

Parameters:

dist - the distribution to sample from

size - the number of values to return

Returns:

an array of size values following the given distribution

nextInt

public int nextInt(int lower,
                   int upper)

Returns a uniformly distributed random integer between lower and upper (inclusive).

Parameters:

lower - lower bound for the generated value

upper - upper bound for the generated value

Returns:

a random integer value within the given bounds

Throws:

MathIllegalArgumentException - if lower is not strictly less than or equal to upper

nextLong

public long nextLong(long lower,
                     long upper)
              throws MathIllegalArgumentException

Returns a uniformly distributed random long integer between lower and upper (inclusive).

Parameters:

lower - lower bound for the generated value

upper - upper bound for the generated value

Returns:

a random long integer value within the given bounds

Throws:

MathIllegalArgumentException - if lower is not strictly less than or equal to upper

nextUniform

public double nextUniform(double lower,
                          double upper)

Returns a double value uniformly distributed over [lower, upper]

Parameters:

lower - lower bound

upper - upper bound

Returns:

uniform deviate

Throws:

MathIllegalArgumentException - if upper is less than or equal to upper

nextZipf

public int nextZipf(int numberOfElements,
                    double exponent)

Returns an integer value following a Zipf distribution with the given parameter.

Parameters:

numberOfElements - number of elements of the distribution

exponent - exponent of the distribution

Returns:

random Zipf value

nextHexString

public String nextHexString(int len)
                     throws MathIllegalArgumentException

Generates a random string of hex characters of length len.

The generated string will be random, but not cryptographically secure.

Algorithm Description: hex strings are generated using a 2-step process.

1. len / 2 + 1 binary bytes are generated using the underlying Random
2. Each binary byte is translated into 2 hex digits

Parameters:

len - the desired string length.

Returns:

the random string.

Throws:

MathIllegalArgumentException - if len <= 0.

nextPermutation

public int[] nextPermutation(int n,
                             int k)
                      throws MathIllegalArgumentException

Generates an integer array of length k whose entries are selected randomly, without repetition, from the integers 0, ..., n - 1 (inclusive).

Generated arrays represent permutations of n taken k at a time.

This method calls MathArrays.shuffle in order to create a random shuffle of the set of natural numbers { 0, 1, ..., n - 1 }.

Parameters:

n - the domain of the permutation

k - the size of the permutation

Returns:

a random k-permutation of n, as an array of integers

Throws:

MathIllegalArgumentException - if k > n.

MathIllegalArgumentException - if k <= 0.

nextSample

public Object[] nextSample(Collection<?> c,
                           int k)
                    throws MathIllegalArgumentException

Returns an array of k objects selected randomly from the Collection c.

Sampling from c is without replacement; but if c contains identical objects, the sample may include repeats. If all elements of c are distinct, the resulting object array represents a Simple Random Sample of size k from the elements of c.

This method calls nextPermutation(c.size(), k) in order to sample the collection.

Parameters:

c - the collection to be sampled

k - the size of the sample

Returns:

a random sample of k elements from c

Throws:

MathIllegalArgumentException - if k > c.size().

MathIllegalArgumentException - if k <= 0.

nextSample

public double[] nextSample(double[] a,
                           int k)
                    throws MathIllegalArgumentException

Returns an array of k double values selected randomly from the double array a.

Sampling from a is without replacement; but if a contains identical objects, the sample may include repeats. If all elements of a are distinct, the resulting object array represents a Simple Random Sample of size k from the elements of a.

Parameters:

a - the array to be sampled

k - the size of the sample

Returns:

a random sample of k elements from a

Throws:

MathIllegalArgumentException - if k > c.size().

MathIllegalArgumentException - if k <= 0.

setSeed

public void setSeed(int seed)

Sets the seed of the underlying random number generator using an int seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Parameters:

seed - the seed value

setSeed

public void setSeed(int[] seed)

Sets the seed of the underlying random number generator using an int array seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Parameters:

seed - the seed value

setSeed

public void setSeed(long seed)

Sets the seed of the underlying random number generator using a long seed.

Sequences of values generated starting with the same seeds should be identical.

Specified by:

setSeed in interface RandomGenerator

Parameters:

seed - the seed value

nextBytes

public void nextBytes(byte[] bytes)

Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.

Specified by:

nextBytes in interface RandomGenerator

Parameters:

bytes - the non-null byte array in which to put the random bytes

nextBytes

public void nextBytes(byte[] bytes,
                      int offset,
                      int length)

Generates random bytes and places them into a user-supplied byte array.

Specified by:

nextBytes in interface RandomGenerator

Parameters:

bytes - the non-null byte array in which to put the random bytes

offset - the starting index for inserting the generated bytes into the array

length - the number of bytes to generate

nextInt

public int nextInt()

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

All 2³² possible int values should be produced with (approximately) equal probability.

Specified by:

nextInt in interface RandomGenerator

Returns:

the next pseudorandom, uniformly distributed int value from this random number generator's sequence

nextInt

public int nextInt(int n)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Specified by:

nextInt in interface RandomGenerator

Parameters:

n - the bound on the random number to be returned. Must be positive.

Returns:

a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).

nextLong

public long nextLong()

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. All 2⁶⁴ possible long values should be produced with (approximately) equal probability.

Specified by:

nextLong in interface RandomGenerator

Returns:

the next pseudorandom, uniformly distributed long value from this random number generator's sequence

nextLong

public long nextLong(long n)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Specified by:

nextLong in interface RandomGenerator

Parameters:

n - the bound on the random number to be returned. Must be positive.

Returns:

a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).

nextBoolean

public boolean nextBoolean()

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.

Specified by:

nextBoolean in interface RandomGenerator

Returns:

the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence

nextFloat

public float nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

Specified by:

nextFloat in interface RandomGenerator

Returns:

the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence

nextDouble

public double nextDouble()

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

Specified by:

nextDouble in interface RandomGenerator

Returns:

the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence

nextGaussian

public double nextGaussian()

Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

Specified by:

nextGaussian in interface RandomGenerator

Returns:

the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence