Package repast.simphony.random

Class RandomHelper

java.lang.Object
repast.simphony.random.RandomHelper
public class RandomHelper extends Object
A helper class for creating random number streams and adding them to a RandomRegistry. Working with random numbers consists of two parts: the actual random number generator and the distributions (e.g. Uniform) take the numbers from the generator and return the appropriate values.

The RandomHelper provides access to default distributions that are created from a default generator. Non-default distributions that use their own random generator or share the default one can also be created. All the create* and get* methods where a name does NOT have to be provided operate on the default generator and distributions. A default uniform distributions is created automatically and the nextInt* and nextDouble* methods will use this distribution.

RandomHelper creates a default random number generator using the current timestamp as the seed. If you do not explicitly set your own seed, the distributions created via the create* calls will use this default generator. However, when the seed is set or reset, all the distributions, both default and non-, are invalidated, and a new random number generator is created as is a new default uniform distribution.

All the distributions in RandomHelper are from the colt library. The return types of the get* and create* methods return these colt objects. See the colt library documentation at http://dsd.lbl.gov/~hoschek/colt/.

  • Constructor Summary

    Constructors
    Constructor
    Description
    RandomHelper()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static cern.jet.random.Beta
    createBeta(double alpha, double beta)
    Creates the default beta distribution using the default random number generator.
    static cern.jet.random.Binomial
    createBinomial(int n, double p)
    Creates the default binomial distribution using the default random number generator.
    static cern.jet.random.BreitWigner
    createBreitWigner(double mean, double gamma, double cut)
    Creates the default Breit Wigner distribution using the default random number generator.
    static cern.jet.random.BreitWignerMeanSquare
    createBreitWignerMeanSquare(double mean, double gamma, double cut)
    Creates the default Breit Wigner mean square state distribution using the default random number generator.
    static cern.jet.random.ChiSquare
    createChiSquare(double freedom)
    Creates the default chi square distribution using the default random number generator.
    static cern.jet.random.Empirical
    createEmpirical(double[] pdf, int interpolationType)
    Creates the default empirical distribution using the default random number generator.
    static cern.jet.random.EmpiricalWalker
    createEmpiricalWalker(double[] pdf, int interpolationType)
    Creates the default empirical walker distribution using the default random number generator.
    static cern.jet.random.Exponential
    createExponential(double lambda)
    Creates the default exponential distribution using the default random number generator.
    static cern.jet.random.ExponentialPower
    createExponentialPower(double tau)
    Creates the default exponential power distribution using the default random number generator.
    static cern.jet.random.Gamma
    createGamma(double alpha, double lambda)
    Creates the default gamma distribution using the default random number generator.
    static cern.jet.random.Hyperbolic
    createHyperbolic(double alpha, double beta)
    Creates the default hyperbolic distribution using the default random number generator.
    static cern.jet.random.HyperGeometric
    createHyperGeometric(int N, int s, int n)
    Creates the default hyper geometric distribution using the default random number generator.
    static cern.jet.random.Logarithmic
    createLogarithmic(double p)
    Creates the default logarithmic distribution using the default random number generator.
    static cern.jet.random.NegativeBinomial
    createNegativeBinomial(int n, double p)
    Creates the default negative binomial distribution using the default random number generator.
    static cern.jet.random.Normal
    createNormal(double mean, double standardDeviation)
    Creates the default normal distribution using the default random number generator.
    static cern.jet.random.Poisson
    createPoisson(double mean)
    Creates the default Poisson distribution using the default random number generator.
    static cern.jet.random.PoissonSlow
    createPoissonSlow(double mean)
    Creates the default slower Poisson distribution using the default random number generator.
    static cern.jet.random.StudentT
    createStudentT(double freedom)
    Creates the default StudentT distribution using the default random number generator.
    static cern.jet.random.Uniform
    createUniform()
    Creates the default Unifrom distribution using the default random number generator.
    static cern.jet.random.Uniform
    createUniform(double min, double max)
    Creates the default uniform distribution using the default random number generator.
    static cern.jet.random.VonMises
    createVonMises(double freedom)
    Creates a default VonMises distribution using the default random number generator.
    static cern.jet.random.Zeta
    createZeta(double ro, double pk)
     
    static cern.jet.random.Beta
    getBeta()
    Gets the default beta distribution.
    static cern.jet.random.Binomial
    getBinomial()
    Gets the default binomial distribution.
    static cern.jet.random.BreitWigner
    getBreitWigner()
    Gets the default BreitWigner distribution.
    static cern.jet.random.BreitWignerMeanSquare
    getBreitWignerMeanSquare()
    Gets the default BreitWignerMeanSquare distribution.
    static cern.jet.random.ChiSquare
    getChiSquare()
    Gets the default Zeta distribution.
    static RandomRegistry
    getDefaultRegistry()
    Gets the default random registry.
    static cern.jet.random.AbstractDistribution
    getDistribution(String name)
    Gets the named previously registered distribution.
    static cern.jet.random.Empirical
    getEmpirical()
    Gets the default ChiSquare distribution.
    static cern.jet.random.EmpiricalWalker
    getEmpiricalWalker()
    Gets the default EmpiricalWalker distribution.
    static cern.jet.random.Exponential
    getExponential()
    Gets the default Exponential distribution.
    static cern.jet.random.ExponentialPower
    getExponentialPower()
    Gets the default exponentialPower distribution.
    static cern.jet.random.Gamma
    getGamma()
    Gets the default gamma distribution.
    static cern.jet.random.engine.RandomEngine
    getGenerator()
    Gets the random number generator used by the default distributions.
    static cern.jet.random.engine.RandomEngine
    getGenerator(String generatorName)
    Gets a previously registered random number generator.
    static cern.jet.random.Hyperbolic
    getHyperbolic()
    Gets the default hyperbolic distribution.
    static cern.jet.random.HyperGeometric
    getHyperGeometric()
    Gets the default hyperGeometric distribution.
    static cern.jet.random.Logarithmic
    getLogarithmic()
    Gets the default logarithmic distribution.
    static cern.jet.random.NegativeBinomial
    getNegativeBinomial()
    Gets the default negativeBinomial distribution.
    static cern.jet.random.Normal
    getNormal()
    Gets the default normal distribution.
    static cern.jet.random.Poisson
    getPoisson()
    Gets the default poisson distribution.
    static cern.jet.random.PoissonSlow
    getPoissonSlow()
    Gets the default slow poisson distribution.
    static int
    getSeed()
    Gets the seed used by the default random number generator.
    static int
    getSeed(String generatorName)
    Gets the seed of the named generator.
    static cern.jet.random.StudentT
    getStudentT()
    Gets the default studentT distribution.
    static cern.jet.random.Uniform
    getUniform()
    Gets the default uniform distribution.
    static cern.jet.random.VonMises
    getVonMises()
    Gets the default vonMises distribution.
    static cern.jet.random.Zeta
    getZeta()
    Gets the default Zeta distribution.
    static void
    init()
    Initializes the random helper.
    static double
    nextDouble()
    This retrieves the next double from the default uniform stream.
    static double
    nextDoubleFromTo(double from, double to)
    This retrieves the next double in the specified range from the default uniform stream.
    static int
    nextInt()
    This retrieves the next integer from the default uniform stream.
    static int
    nextIntFromTo(int from, int to)
    This retrieves the next integer in the specified range from the default uniform stream.
    static void
    registerDistribution(String name, cern.jet.random.AbstractDistribution dist)
    Registers the named random number distribution for later retrieval.
    static cern.jet.random.engine.RandomEngine
    registerGenerator(String name, int seed)
    Creates and registers a new random number generator with the specified name and seed.
    static void
    setSeed(int seed)
    This sets the seed for the default stream.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • RandomHelper

      public RandomHelper()

  • Method Details

    • createBeta

      public static cern.jet.random.Beta createBeta(double alpha, double beta)
      Creates the default beta distribution using the default random number generator.
      Parameters:
      alpha -
      beta -
      Returns:
      the created distribution

    • createBinomial

      public static cern.jet.random.Binomial createBinomial(int n, double p)
      Creates the default binomial distribution using the default random number generator.
      Parameters:
      n -
      p -

    • createBreitWigner

      public static cern.jet.random.BreitWigner createBreitWigner(double mean, double gamma, double cut)
      Creates the default Breit Wigner distribution using the default random number generator.
      Parameters:
      mean -
      gamma -
      cut -
      Returns:
      the created distribution

    • createBreitWignerMeanSquare

      public static cern.jet.random.BreitWignerMeanSquare createBreitWignerMeanSquare(double mean, double gamma, double cut)
      Creates the default Breit Wigner mean square state distribution using the default random number generator.
      Parameters:
      mean -
      gamma -
      cut -
      Returns:
      the created distribution

    • createChiSquare

      public static cern.jet.random.ChiSquare createChiSquare(double freedom)
      Creates the default chi square distribution using the default random number generator.
      Parameters:
      freedom -
      Returns:
      the created distribution

    • createEmpirical

      public static cern.jet.random.Empirical createEmpirical(double[] pdf, int interpolationType)
      Creates the default empirical distribution using the default random number generator.
      Parameters:
      pdf -
      interpolationType -
      Returns:
      the created distribution

    • createEmpiricalWalker

      public static cern.jet.random.EmpiricalWalker createEmpiricalWalker(double[] pdf, int interpolationType)
      Creates the default empirical walker distribution using the default random number generator.
      Parameters:
      pdf -
      interpolationType -
      Returns:
      the created distribution

    • createExponential

      public static cern.jet.random.Exponential createExponential(double lambda)
      Creates the default exponential distribution using the default random number generator.
      Parameters:
      lambda -
      Returns:
      the created distribution

    • createExponentialPower

      public static cern.jet.random.ExponentialPower createExponentialPower(double tau)
      Creates the default exponential power distribution using the default random number generator.
      Parameters:
      tau -
      Returns:
      the created distribution

    • createGamma

      public static cern.jet.random.Gamma createGamma(double alpha, double lambda)
      Creates the default gamma distribution using the default random number generator.
      Parameters:
      alpha -
      lambda -
      Returns:
      the created distribution

    • createHyperbolic

      public static cern.jet.random.Hyperbolic createHyperbolic(double alpha, double beta)
      Creates the default hyperbolic distribution using the default random number generator.
      Parameters:
      alpha -
      beta -
      Returns:
      the created distribution

    • createHyperGeometric

      public static cern.jet.random.HyperGeometric createHyperGeometric(int N, int s, int n)
      Creates the default hyper geometric distribution using the default random number generator.
      Parameters:
      N -
      s -
      n -
      Returns:
      the created distribution

    • createLogarithmic

      public static cern.jet.random.Logarithmic createLogarithmic(double p)
      Creates the default logarithmic distribution using the default random number generator.
      Parameters:
      p -
      Returns:
      the created distribution

    • createNegativeBinomial

      public static cern.jet.random.NegativeBinomial createNegativeBinomial(int n, double p)
      Creates the default negative binomial distribution using the default random number generator.
      Parameters:
      n -
      p -
      Returns:
      the created distribution

    • createNormal

      public static cern.jet.random.Normal createNormal(double mean, double standardDeviation)
      Creates the default normal distribution using the default random number generator.
      Parameters:
      mean -
      standardDeviation -
      Returns:
      the created distribution

    • createPoisson

      public static cern.jet.random.Poisson createPoisson(double mean)
      Creates the default Poisson distribution using the default random number generator.
      Parameters:
      mean -
      Returns:
      the created distribution

    • createPoissonSlow

      public static cern.jet.random.PoissonSlow createPoissonSlow(double mean)
      Creates the default slower Poisson distribution using the default random number generator.
      Parameters:
      mean -
      Returns:
      the created distribution

    • createStudentT

      public static cern.jet.random.StudentT createStudentT(double freedom)
      Creates the default StudentT distribution using the default random number generator.
      Parameters:
      freedom -
      Returns:
      the created distribution

    • createUniform

      public static cern.jet.random.Uniform createUniform()
      Creates the default Unifrom distribution using the default random number generator.
      Returns:
      the created distribution

    • createUniform

      public static cern.jet.random.Uniform createUniform(double min, double max)
      Creates the default uniform distribution using the default random number generator.
      Parameters:
      min -
      max -
      Returns:
      the created distribution

    • createVonMises

      public static cern.jet.random.VonMises createVonMises(double freedom)
      Creates a default VonMises distribution using the default random number generator.
      Parameters:
      freedom -
      Returns:
      the created distribution

    • createZeta

      public static cern.jet.random.Zeta createZeta(double ro, double pk)

    • getBeta

      public static cern.jet.random.Beta getBeta()
      Gets the default beta distribution.
      Returns:
      the default beta distribution.

    • getBinomial

      public static cern.jet.random.Binomial getBinomial()
      Gets the default binomial distribution.
      Returns:
      the default binomial distribution.

    • getBreitWigner

      public static cern.jet.random.BreitWigner getBreitWigner()
      Gets the default BreitWigner distribution.
      Returns:
      the default BreitWigner distribution.

    • getBreitWignerMeanSquare

      public static cern.jet.random.BreitWignerMeanSquare getBreitWignerMeanSquare()
      Gets the default BreitWignerMeanSquare distribution.
      Returns:
      the default BreitWignerMeanSquare distribution.

    • getChiSquare

      public static cern.jet.random.ChiSquare getChiSquare()
      Gets the default Zeta distribution.
      Returns:
      the default Zeta distribution.

    • getEmpirical

      public static cern.jet.random.Empirical getEmpirical()
      Gets the default ChiSquare distribution.
      Returns:
      the default ChiSquare distribution.

    • getEmpiricalWalker

      public static cern.jet.random.EmpiricalWalker getEmpiricalWalker()
      Gets the default EmpiricalWalker distribution.
      Returns:
      the default EmpiricalWalker distribution.

    • getExponential

      public static cern.jet.random.Exponential getExponential()
      Gets the default Exponential distribution.
      Returns:
      the default Exponential distribution.

    • getExponentialPower

      public static cern.jet.random.ExponentialPower getExponentialPower()
      Gets the default exponentialPower distribution.
      Returns:
      the default exponentialPower distribution.

    • getGamma

      public static cern.jet.random.Gamma getGamma()
      Gets the default gamma distribution.
      Returns:
      the default gamma distribution.

    • getHyperbolic

      public static cern.jet.random.Hyperbolic getHyperbolic()
      Gets the default hyperbolic distribution.
      Returns:
      the default hyperbolic distribution.

    • getHyperGeometric

      public static cern.jet.random.HyperGeometric getHyperGeometric()
      Gets the default hyperGeometric distribution.
      Returns:
      the default hyperGeometric distribution.

    • getLogarithmic

      public static cern.jet.random.Logarithmic getLogarithmic()
      Gets the default logarithmic distribution.
      Returns:
      the default logarithmic distribution.

    • getNegativeBinomial

      public static cern.jet.random.NegativeBinomial getNegativeBinomial()
      Gets the default negativeBinomial distribution.
      Returns:
      the default negativeBinomial distribution.

    • getNormal

      public static cern.jet.random.Normal getNormal()
      Gets the default normal distribution.
      Returns:
      the default normal distribution.

    • getPoisson

      public static cern.jet.random.Poisson getPoisson()
      Gets the default poisson distribution.
      Returns:
      the default poisson distribution.

    • getPoissonSlow

      public static cern.jet.random.PoissonSlow getPoissonSlow()
      Gets the default slow poisson distribution.
      Returns:
      the default slow poisson distribution.

    • getStudentT

      public static cern.jet.random.StudentT getStudentT()
      Gets the default studentT distribution.
      Returns:
      the default studentT distribution.

    • getUniform

      public static cern.jet.random.Uniform getUniform()
      Gets the default uniform distribution.
      Returns:
      the default uniform distribution.

    • getVonMises

      public static cern.jet.random.VonMises getVonMises()
      Gets the default vonMises distribution.
      Returns:
      the default vonMises distribution.

    • getZeta

      public static cern.jet.random.Zeta getZeta()
      Gets the default Zeta distribution.
      Returns:
      the default Zeta distribution.

    • setSeed

      public static void setSeed(int seed)
      This sets the seed for the default stream. This is the same as DEFAULT_REGISTRY.setSeed(RandomHelper.DEFAULT_STREAM, seed);

      The default stream will be created if it has not yet been.

      Parameters:
      seed - the seed

    • nextDoubleFromTo

      public static double nextDoubleFromTo(double from, double to)
      This retrieves the next double in the specified range from the default uniform stream.
      Parameters:
      from - the start of the range (exclusive)
      to - the end of the range (exclusive)
      Returns:
      the next double from the default uniform stream

    • nextDouble

      public static double nextDouble()
      This retrieves the next double from the default uniform stream. T
      Returns:
      the next double from the default uniform stream

    • nextIntFromTo

      public static int nextIntFromTo(int from, int to)
      This retrieves the next integer in the specified range from the default uniform stream.
      Parameters:
      from - the start of the range (inclusive)
      to - the end of the range (inclusive)
      Returns:
      the next int from the default uniform stream

    • nextInt

      public static int nextInt()
      This retrieves the next integer from the default uniform stream.
      Returns:
      the next int from the default uniform stream

    • init

      public static void init()
      Initializes the random helper. This will invalidate any previously created distributions, both default and custom) and set the current seed for default generator to the current system time. This will also recreate the default uniform distribution.

    • getDefaultRegistry

      public static RandomRegistry getDefaultRegistry()
      Gets the default random registry.
      Returns:
      the default random registry

    • getGenerator

      public static cern.jet.random.engine.RandomEngine getGenerator()
      Gets the random number generator used by the default distributions.
      Returns:
      the random number generator used by the default distributions.

    • getSeed

      public static int getSeed()
      Gets the seed used by the default random number generator.
      Returns:
      the seed used by the default random number generator.

    • registerGenerator

      public static cern.jet.random.engine.RandomEngine registerGenerator(String name, int seed)
      Creates and registers a new random number generator with the specified name and seed. The generator can then be retrieved later using #getGenerator(String).

      Parameters:
      name - the name of the generator to create and register
      seed - the new generators seed
      Returns:
      the new generator itself

    • getGenerator

      public static cern.jet.random.engine.RandomEngine getGenerator(String generatorName)
      Gets a previously registered random number generator.
      Parameters:
      generatorName - the name of the generator to get
      Returns:
      a previously registered random number generator.

    • getSeed

      public static int getSeed(String generatorName)
      Gets the seed of the named generator.
      Parameters:
      generatorName - the name of the generator
      Returns:
      the seed of the named generator.

    • registerDistribution

      public static void registerDistribution(String name, cern.jet.random.AbstractDistribution dist)
      Registers the named random number distribution for later retrieval.
      Parameters:
      name - the name of the distribution
      dist - the distribution to register

    • getDistribution

      public static cern.jet.random.AbstractDistribution getDistribution(String name)
      Gets the named previously registered distribution. Calling code can then cast the distribution into the appropriate type (e.g. a Normal).
      Parameters:
      name - the name of the distribution to get
      Returns:
      the named previously registered distribution.