cc.mallet.util
Class Randoms

java.lang.Object
  java.util.Random
      cc.mallet.util.Randoms

All Implemented Interfaces:

java.io.Serializable

public class Randoms
extends java.util.Random

See Also:

Serialized Form

Constructor Summary

Randoms()

Randoms(int seed)

Method Summary

java.util.Random	asJavaRandom() Deprecated.
static void	main(java.lang.String[] args)
double	nextBeta(double alpha, double beta) Return a random double drawn from a Beta distribution with mean a/(a+b) and variance ab/((a+b+1)(a+b)^2).
java.util.BitSet	nextBitSet(int size, double p) Return a random BitSet with "size" bits, each having probability p of being true.
boolean	nextBoolean() Return a random boolean, equally likely to be true or false.
boolean	nextBoolean(double p) Return a random boolean, with probability p of being true.
double	nextChiSq() Return a random double drawn from an Chi-squarted distribution with mean 1 and variance 2.
double	nextChiSq(int df) Return a random double drawn from an Chi-squared distribution with mean df and variance 2*df.
double	nextChiSq(int df, double lambda) Return a random double drawn from an Chi-squared distribution with mean df+lambda and variance 2*df.
int	nextDiscrete(double[] a) Draw a single sample from multinomial "a".
int	nextDiscrete(double[] a, double sum) draw a single sample from (unnormalized) multinomial "a", with normalizing factor "sum".
double	nextExp() Return a random double drawn from an Exponential distribution with mean 1 and variance 1.
double	nextExp(double beta) Return a random double drawn from an Exponential distribution with mean beta and variance beta^2.
double	nextExp(double beta, double lambda) Return a random double drawn from an Exponential distribution with mean beta+lambda and variance beta^2.
double	nextGamma() Return a random double drawn from a Gamma distribution with mean 1.0 and variance 1.0.
double	nextGamma(double alpha) Return a random double drawn from a Gamma distribution with mean alpha and variance 1.0.
double	nextGamma(double alpha, double beta) Return a random double drawn from a Gamma distribution with mean alpha*beta and variance alpha*beta^2.
double	nextGamma(double alpha, double beta, double lambda) Return a random double drawn from a Gamma distribution with mean alpha*beta+lamba and variance alpha*beta^2.
double	nextGaussian() Return a random double drawn from a Gaussian distribution with mean 0 and variance 1.
double	nextGaussian(double m, double s2) Return a random double drawn from a Gaussian distribution with mean m and variance s2.
int	nextPoisson() Return nextPoisson(1).
int	nextPoisson(double lambda) Return random integer from Poission with parameter lambda.
double	nextUniform() Return a random double in the range 0 to 1, inclusive, uniformly sampled from that range.
double	nextUniform(double a, double b) Return a random double in the range a to b, inclusive, uniformly sampled from that range.
double	oldNextGamma(int ia)

Methods inherited from class java.util.Random

next, nextBytes, nextDouble, nextFloat, nextInt, nextInt, nextLong, setSeed

Methods inherited from class java.lang.Object

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

Constructor Detail

Randoms

public Randoms(int seed)

Randoms

public Randoms()

Method Detail

nextPoisson

public int nextPoisson(double lambda)

Return random integer from Poission with parameter lambda. The mean of this distribution is lambda. The variance is lambda.

nextPoisson

public int nextPoisson()

Return nextPoisson(1).

nextBoolean

public boolean nextBoolean()

Return a random boolean, equally likely to be true or false.

Overrides:

nextBoolean in class java.util.Random

nextBoolean

public boolean nextBoolean(double p)

Return a random boolean, with probability p of being true.

nextBitSet

public java.util.BitSet nextBitSet(int size,
                                   double p)

Return a random BitSet with "size" bits, each having probability p of being true.

nextUniform

public double nextUniform()

Return a random double in the range 0 to 1, inclusive, uniformly sampled from that range. The mean of this distribution is 0.5. The variance is 1/12.

nextUniform

public double nextUniform(double a,
                          double b)

Return a random double in the range a to b, inclusive, uniformly sampled from that range. The mean of this distribution is (b-a)/2. The variance is (b-a)^2/12

nextDiscrete

public int nextDiscrete(double[] a)

Draw a single sample from multinomial "a".

nextDiscrete

public int nextDiscrete(double[] a,
                        double sum)

draw a single sample from (unnormalized) multinomial "a", with normalizing factor "sum".

nextGaussian

public double nextGaussian()

Return a random double drawn from a Gaussian distribution with mean 0 and variance 1.

Overrides:

nextGaussian in class java.util.Random

nextGaussian

public double nextGaussian(double m,
                           double s2)

Return a random double drawn from a Gaussian distribution with mean m and variance s2.

nextGamma

public double nextGamma()

Return a random double drawn from a Gamma distribution with mean 1.0 and variance 1.0.

nextGamma

public double nextGamma(double alpha)

Return a random double drawn from a Gamma distribution with mean alpha and variance 1.0.

oldNextGamma

public double oldNextGamma(int ia)

nextGamma

public double nextGamma(double alpha,
                        double beta)

Return a random double drawn from a Gamma distribution with mean alpha*beta and variance alpha*beta^2.

nextGamma

public double nextGamma(double alpha,
                        double beta,
                        double lambda)

Return a random double drawn from a Gamma distribution with mean alpha*beta+lamba and variance alpha*beta^2. Note that this means the pdf is: frac{ x^{alpha-1} exp(-x/beta) }{ beta^alpha Gamma(alpha) } in other words, beta is a "scale" parameter. An alternative parameterization would use 1/beta, the "rate" parameter.

nextExp

public double nextExp()

Return a random double drawn from an Exponential distribution with mean 1 and variance 1.

nextExp

public double nextExp(double beta)

Return a random double drawn from an Exponential distribution with mean beta and variance beta^2.

nextExp

public double nextExp(double beta,
                      double lambda)

Return a random double drawn from an Exponential distribution with mean beta+lambda and variance beta^2.

nextChiSq

public double nextChiSq()

Return a random double drawn from an Chi-squarted distribution with mean 1 and variance 2. Equivalent to nextChiSq(1)

nextChiSq

public double nextChiSq(int df)

Return a random double drawn from an Chi-squared distribution with mean df and variance 2*df.

nextChiSq

public double nextChiSq(int df,
                        double lambda)

Return a random double drawn from an Chi-squared distribution with mean df+lambda and variance 2*df.

nextBeta

public double nextBeta(double alpha,
                       double beta)

Return a random double drawn from a Beta distribution with mean a/(a+b) and variance ab/((a+b+1)(a+b)^2).

asJavaRandom

@Deprecated
public java.util.Random asJavaRandom()

Deprecated.

Wrap this instance as a java random, so it can be passed to legacy methods. All methods of the returned java.util.Random object will affect the state of this object, as well.

main

public static void main(java.lang.String[] args)