RandomDataImpl
org.apache.commons.math3.random

Class RandomDataImpl

  • All Implemented Interfaces:
    Serializable, RandomData

    Deprecated. 
    to be removed in 4.0. Use RandomDataGenerator instead

    @Deprecatedpublic class RandomDataImplextends Objectimplements RandomData, Serializable
    Generates random deviates and other random data using a RandomGenerator instance to generate non-secure data and a SecureRandom instance to provide data for the nextSecureXxx methods. If no RandomGenerator is provided in the constructor, the default is to use a Well19937c generator. To plug in a different implementation, either implement RandomGenerator directly or extend AbstractRandomGenerator.

    Supports reseeding the underlying pseudo-random number generator (PRNG). The SecurityProvider and Algorithm used by the SecureRandom instance can also be reset.

    For details on the default PRNGs, see Random and SecureRandom.

    Usage Notes:

    • Instance variables are used to maintain RandomGenerator and SecureRandom instances used in data generation. Therefore, to generate a random sequence of values or strings, you should use just one RandomDataGenerator instance repeatedly.
    • The "secure" methods are *much* slower. These should be used only when a cryptographically secure random sequence is required. A secure random sequence is a sequence of pseudo-random values which, in addition to being well-dispersed (so no subsequence of values is an any more likely than other subsequence of the the same length), also has the additional property that knowledge of values generated up to any point in the sequence does not make it any easier to predict subsequent values.
    • When a new RandomDataGenerator is created, the underlying random number generators are not initialized. If you do not explicitly seed the default non-secure generator, it is seeded with the current time in milliseconds plus the system identity hash code on first use. The same holds for the secure generator. If you provide a RandomGenerator to the constructor, however, this generator is not reseeded by the constructor nor is it reseeded on first use.
    • The reSeed and reSeedSecure methods delegate to the corresponding methods on the underlying RandomGenerator and SecureRandom instances. Therefore, reSeed(long) fully resets the initial state of the non-secure random number generator (so that reseeding with a specific value always results in the same subsequent random sequence); whereas reSeedSecure(long) does not reinitialize the secure random number generator (so secure sequences started with calls to reseedSecure(long) won't be identical).
    • This implementation is not synchronized. The underlying RandomGenerator or SecureRandom instances are not protected by synchronization and are not guaranteed to be thread-safe. Therefore, if an instance of this class is concurrently utilized by multiple threads, it is the responsibility of client code to synchronize access to seeding and data generation methods.

    See Also:
    Serialized Form
    • Constructor Summary

      Constructors 
      Constructor and Description
      RandomDataImpl()
      Deprecated. 
      Construct a RandomDataImpl, using a default random generator as the source of randomness.
      RandomDataImpl(RandomGenerator rand)
      Deprecated. 
      Construct a RandomDataImpl using the supplied RandomGenerator as the source of (non-secure) random data.
    • Method Summary

      Methods 
      Modifier and TypeMethod and Description
      doublenextBeta(double alpha, double beta)
      Deprecated. 
      Generates a random value from the Beta Distribution.
      intnextBinomial(int numberOfTrials, double probabilityOfSuccess)
      Deprecated. 
      Generates a random value from the Binomial Distribution.
      doublenextCauchy(double median, double scale)
      Deprecated. 
      Generates a random value from the Cauchy Distribution.
      doublenextChiSquare(double df)
      Deprecated. 
      Generates a random value from the ChiSquare Distribution.
      doublenextExponential(double mean)
      Deprecated. 
      Generates a random value from the exponential distribution with specified mean.
      doublenextF(double numeratorDf, double denominatorDf)
      Deprecated. 
      Generates a random value from the F Distribution.
      doublenextGamma(double shape, double scale)
      Deprecated. 
      Generates a random value from the Gamma Distribution.
      doublenextGaussian(double mu, double sigma)
      Deprecated. 
      Generates a random value from the Normal (or Gaussian) distribution with specified mean and standard deviation.
      StringnextHexString(int len)
      Deprecated. 
      Generates a random string of hex characters of length len.
      intnextHypergeometric(int populationSize, int numberOfSuccesses, int sampleSize)
      Deprecated. 
      Generates a random value from the Hypergeometric Distribution.
      intnextInt(int lower, int upper)
      Deprecated. 
      Generates a uniformly distributed random integer between lower and upper (endpoints included).
      intnextInversionDeviate(IntegerDistribution distribution)
      Deprecated. 
      use the distribution's sample() method
      doublenextInversionDeviate(RealDistribution distribution)
      Deprecated. 
      use the distribution's sample() method
      longnextLong(long lower, long upper)
      Deprecated. 
      Generates a uniformly distributed random long integer between lower and upper (endpoints included).
      intnextPascal(int r, double p)
      Deprecated. 
      Generates a random value from the Pascal Distribution.
      int[]nextPermutation(int n, int k)
      Deprecated. 
      Generates an integer array of length k whose entries are selected randomly, without repetition, from the integers 0, ..., n - 1 (inclusive).
      longnextPoisson(double mean)
      Deprecated. 
      Generates a random value from the Poisson distribution with the given mean.
      Object[]nextSample(Collection<?> c, int k)
      Deprecated. 
      Returns an array of k objects selected randomly from the Collection c.
      StringnextSecureHexString(int len)
      Deprecated. 
      Generates a random string of hex characters from a secure random sequence.
      intnextSecureInt(int lower, int upper)
      Deprecated. 
      Generates a uniformly distributed random integer between lower and upper (endpoints included) from a secure random sequence.
      longnextSecureLong(long lower, long upper)
      Deprecated. 
      Generates a uniformly distributed random long integer between lower and upper (endpoints included) from a secure random sequence.
      doublenextT(double df)
      Deprecated. 
      Generates a random value from the T Distribution.
      doublenextUniform(double lower, double upper)
      Deprecated. 
      Generates a uniformly distributed random value from the open interval (lower, upper) (i.e., endpoints excluded).
      doublenextUniform(double lower, double upper, boolean lowerInclusive)
      Deprecated. 
      Generates a uniformly distributed random value from the interval (lower, upper) or the interval [lower, upper).
      doublenextWeibull(double shape, double scale)
      Deprecated. 
      Generates a random value from the Weibull Distribution.
      intnextZipf(int numberOfElements, double exponent)
      Deprecated. 
      Generates a random value from the Zipf Distribution.
      voidreSeed()
      Deprecated. 
      Reseeds the random number generator with System.currentTimeMillis() + System.identityHashCode(this)).
      voidreSeed(long seed)
      Deprecated. 
      Reseeds the random number generator with the supplied seed.
      voidreSeedSecure()
      Deprecated. 
      Reseeds the secure random number generator with the current time in milliseconds.
      voidreSeedSecure(long seed)
      Deprecated. 
      Reseeds the secure random number generator with the supplied seed.
      voidsetSecureAlgorithm(String algorithm, String provider)
      Deprecated. 
      Sets the PRNG algorithm for the underlying SecureRandom instance using the Security Provider API.
    • Constructor Detail

      • RandomDataImpl

        public RandomDataImpl()
        Deprecated. 
        Construct a RandomDataImpl, using a default random generator as the source of randomness.

        The default generator is a Well19937c seeded with System.currentTimeMillis() + System.identityHashCode(this)). The generator is initialized and seeded on first use.

      • RandomDataImpl

        public RandomDataImpl(RandomGenerator rand)
        Deprecated. 
        Construct a RandomDataImpl using the supplied RandomGenerator as the source of (non-secure) random data.
        Parameters:
        rand - the source of (non-secure) random data (may be null, resulting in the default generator)
    • Method Detail

      • nextHexString

        public String nextHexString(int len)                     throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random string of hex characters of length len.

        The generated string will be random, but not cryptographically secure. To generate cryptographically secure strings, use RandomData.nextSecureHexString(int).

        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

        Specified by:
        nextHexString in interface RandomData
        Parameters:
        len - the desired string length.
        Returns:
        the random string.
        Throws:
        NotStrictlyPositiveException - if len <= 0.
      • nextInt

        public int nextInt(int lower,          int upper)            throws NumberIsTooLargeException
        Deprecated. 
        Generates a uniformly distributed random integer between lower and upper (endpoints included).

        The generated integer will be random, but not cryptographically secure. To generate cryptographically secure integer sequences, use RandomData.nextSecureInt(int, int).

        Specified by:
        nextInt in interface RandomData
        Parameters:
        lower - lower bound for generated integer
        upper - upper bound for generated integer
        Returns:
        a random integer greater than or equal to lower and less than or equal to upper
        Throws:
        NumberIsTooLargeException - if lower >= upper
      • nextLong

        public long nextLong(long lower,            long upper)              throws NumberIsTooLargeException
        Deprecated. 
        Generates a uniformly distributed random long integer between lower and upper (endpoints included).

        The generated long integer values will be random, but not cryptographically secure. To generate cryptographically secure sequences of longs, use RandomData.nextSecureLong(long, long).

        Specified by:
        nextLong in interface RandomData
        Parameters:
        lower - lower bound for generated long integer
        upper - upper bound for generated long integer
        Returns:
        a random long integer greater than or equal to lower and less than or equal to upper
        Throws:
        NumberIsTooLargeException - if lower >= upper
      • nextSecureHexString

        public String nextSecureHexString(int len)                           throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random string of hex characters from a secure random sequence.

        If cryptographic security is not required, use RandomData.nextHexString(int).

        Algorithm Description: hex strings are generated in 40-byte segments using a 3-step process.

        1. 20 random bytes are generated using the underlying SecureRandom.
        2. SHA-1 hash is applied to yield a 20-byte binary digest.
        3. Each byte of the binary digest is converted to 2 hex digits.

        Specified by:
        nextSecureHexString in interface RandomData
        Parameters:
        len - the length of the string to be generated
        Returns:
        a random string of hex characters of length len
        Throws:
        NotStrictlyPositiveException - if len <= 0
      • nextSecureInt

        public int nextSecureInt(int lower,                int upper)                  throws NumberIsTooLargeException
        Deprecated. 
        Generates a uniformly distributed random integer between lower and upper (endpoints included) from a secure random sequence.

        Sequences of integers generated using this method will be cryptographically secure. If cryptographic security is not required, RandomData.nextInt(int, int) should be used instead of this method.

        Definition: Secure Random Sequence

        Specified by:
        nextSecureInt in interface RandomData
        Parameters:
        lower - lower bound for generated integer
        upper - upper bound for generated integer
        Returns:
        a random integer greater than or equal to lower and less than or equal to upper.
        Throws:
        NumberIsTooLargeException - if lower >= upper.
      • nextSecureLong

        public long nextSecureLong(long lower,                  long upper)                    throws NumberIsTooLargeException
        Deprecated. 
        Generates a uniformly distributed random long integer between lower and upper (endpoints included) from a secure random sequence.

        Sequences of long values generated using this method will be cryptographically secure. If cryptographic security is not required, RandomData.nextLong(long, long) should be used instead of this method.

        Definition: Secure Random Sequence

        Specified by:
        nextSecureLong in interface RandomData
        Parameters:
        lower - lower bound for generated integer
        upper - upper bound for generated integer
        Returns:
        a random long integer greater than or equal to lower and less than or equal to upper.
        Throws:
        NumberIsTooLargeException - if lower >= upper.
      • nextPoisson

        public long nextPoisson(double mean)                 throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the Poisson distribution with the given mean.

        Definition: Poisson Distribution

        Algorithm Description:

        • For small means, uses simulation of a Poisson process using Uniform deviates, as described here. The Poisson process (and hence value returned) is bounded by 1000 * mean.
        • For large means, uses the rejection algorithm described in
          Devroye, Luc. (1981).The Computer Generation of Poisson Random Variables Computing vol. 26 pp. 197-207.

        Specified by:
        nextPoisson in interface RandomData
        Parameters:
        mean - the mean of the Poisson distribution
        Returns:
        a random value following the specified Poisson distribution
        Throws:
        NotStrictlyPositiveException - if mean <= 0.
      • nextGaussian

        public double nextGaussian(double mu,                  double sigma)                    throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the Normal (or Gaussian) distribution with specified mean and standard deviation.

        Definition: Normal Distribution

        Specified by:
        nextGaussian in interface RandomData
        Parameters:
        mu - the mean of the distribution
        sigma - the standard deviation of the distribution
        Returns:
        a random value following the specified Gaussian distribution
        Throws:
        NotStrictlyPositiveException - if sigma <= 0.
      • nextExponential

        public double nextExponential(double mean)                       throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the exponential distribution with specified mean.

        Definition: Exponential Distribution

        Algorithm Description: Uses the Algorithm SA (Ahrens) from p. 876 in: [1]: Ahrens, J. H. and Dieter, U. (1972). Computer methods for sampling from the exponential and normal distributions. Communications of the ACM, 15, 873-882.

        Specified by:
        nextExponential in interface RandomData
        Parameters:
        mean - the mean of the distribution
        Returns:
        a random value following the specified exponential distribution
        Throws:
        NotStrictlyPositiveException - if mean <= 0.
      • nextUniform

        public double nextUniform(double lower,                 double upper,                 boolean lowerInclusive)                   throws NumberIsTooLargeException,                          NotFiniteNumberException,                          NotANumberException
        Deprecated. 
        Generates a uniformly distributed random value from the interval (lower, upper) or the interval [lower, upper). The lower bound is thus optionally included, while the upper bound is always excluded.

        Definition: Uniform Distribution lower and upper - lower are the location and scale parameters, respectively.

        Algorithm Description: if the lower bound is excluded, scales the output of Random.nextDouble(), but rejects 0 values (i.e., will generate another random double if Random.nextDouble() returns 0). This is necessary to provide a symmetric output interval (both endpoints excluded).

        Specified by:
        nextUniform in interface RandomData
        Parameters:
        lower - the lower bound of the support
        upper - the exclusive upper bound of the support
        lowerInclusive - true if the lower bound is inclusive
        Returns:
        uniformly distributed random value in the (lower, upper) interval, if lowerInclusive is false, or in the [lower, upper) interval, if lowerInclusive is true
        Throws:
        NumberIsTooLargeException - if lower >= upper
        NotFiniteNumberException - if one of the bounds is infinite
        NotANumberException - if one of the bounds is NaN
      • nextBeta

        public double nextBeta(double alpha,              double beta)
        Deprecated. 
        Generates a random value from the Beta Distribution. This implementation uses inversion to generate random values.
        Parameters:
        alpha - first distribution shape parameter
        beta - second distribution shape parameter
        Returns:
        random value sampled from the beta(alpha, beta) distribution
      • nextBinomial

        public int nextBinomial(int numberOfTrials,               double probabilityOfSuccess)
        Deprecated. 
        Generates a random value from the Binomial Distribution. This implementation uses inversion to generate random values.
        Parameters:
        numberOfTrials - number of trials of the Binomial distribution
        probabilityOfSuccess - probability of success of the Binomial distribution
        Returns:
        random value sampled from the Binomial(numberOfTrials, probabilityOfSuccess) distribution
      • nextCauchy

        public double nextCauchy(double median,                double scale)
        Deprecated. 
        Generates a random value from the Cauchy Distribution. This implementation uses inversion to generate random values.
        Parameters:
        median - the median of the Cauchy distribution
        scale - the scale parameter of the Cauchy distribution
        Returns:
        random value sampled from the Cauchy(median, scale) distribution
      • nextChiSquare

        public double nextChiSquare(double df)
        Deprecated. 
        Generates a random value from the ChiSquare Distribution. This implementation uses inversion to generate random values.
        Parameters:
        df - the degrees of freedom of the ChiSquare distribution
        Returns:
        random value sampled from the ChiSquare(df) distribution
      • nextF

        public double nextF(double numeratorDf,           double denominatorDf)             throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the F Distribution. This implementation uses inversion to generate random values.
        Parameters:
        numeratorDf - the numerator degrees of freedom of the F distribution
        denominatorDf - the denominator degrees of freedom of the F distribution
        Returns:
        random value sampled from the F(numeratorDf, denominatorDf) distribution
        Throws:
        NotStrictlyPositiveException - if numeratorDf <= 0 or denominatorDf <= 0.
      • nextGamma

        public double nextGamma(double shape,               double scale)                 throws NotStrictlyPositiveException
        Deprecated. 

        Generates a random value from the Gamma Distribution.

        This implementation uses the following algorithms:

        For 0 < shape < 1:
        Ahrens, J. H. and Dieter, U., Computer methods for sampling from gamma, beta, Poisson and binomial distributions. Computing, 12, 223-246, 1974.

        For shape >= 1:
        Marsaglia and Tsang, A Simple Method for Generating Gamma Variables. ACM Transactions on Mathematical Software, Volume 26 Issue 3, September, 2000.

        Parameters:
        shape - the median of the Gamma distribution
        scale - the scale parameter of the Gamma distribution
        Returns:
        random value sampled from the Gamma(shape, scale) distribution
        Throws:
        NotStrictlyPositiveException - if shape <= 0 or scale <= 0.
      • nextWeibull

        public double nextWeibull(double shape,                 double scale)                   throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the Weibull Distribution. This implementation uses inversion to generate random values.
        Parameters:
        shape - the shape parameter of the Weibull distribution
        scale - the scale parameter of the Weibull distribution
        Returns:
        random value sampled from the Weibull(shape, size) distribution
        Throws:
        NotStrictlyPositiveException - if shape <= 0 or scale <= 0.
      • nextZipf

        public int nextZipf(int numberOfElements,           double exponent)             throws NotStrictlyPositiveException
        Deprecated. 
        Generates a random value from the Zipf Distribution. This implementation uses inversion to generate random values.
        Parameters:
        numberOfElements - the number of elements of the ZipfDistribution
        exponent - the exponent of the ZipfDistribution
        Returns:
        random value sampled from the Zipf(numberOfElements, exponent) distribution
        Throws:
        NotStrictlyPositiveException - if numberOfElements <= 0 or exponent <= 0.
      • reSeed

        public void reSeed(long seed)
        Deprecated. 
        Reseeds the random number generator with the supplied seed.

        Will create and initialize if null.

        Parameters:
        seed - the seed value to use
      • reSeedSecure

        public void reSeedSecure()
        Deprecated. 
        Reseeds the secure random number generator with the current time in milliseconds.

        Will create and initialize if null.

      • reSeedSecure

        public void reSeedSecure(long seed)
        Deprecated. 
        Reseeds the secure random number generator with the supplied seed.

        Will create and initialize if null.

        Parameters:
        seed - the seed value to use
      • reSeed

        public void reSeed()
        Deprecated. 
        Reseeds the random number generator with System.currentTimeMillis() + System.identityHashCode(this)).
      • nextPermutation

        public int[] nextPermutation(int n,                    int k)                      throws NotStrictlyPositiveException,                             NumberIsTooLargeException
        Deprecated. 
        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.

        Uses a 2-cycle permutation shuffle. The shuffling process is described here.

        Specified by:
        nextPermutation in interface RandomData
        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:
        NotStrictlyPositiveException - if k <= 0.
        NumberIsTooLargeException - if k > n.
      • nextSample

        public Object[] nextSample(Collection<?> c,                  int k)                    throws NotStrictlyPositiveException,                           NumberIsTooLargeException
        Deprecated. 
        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.

        Algorithm Description: Uses a 2-cycle permutation shuffle to generate a random permutation of c.size() and then returns the elements whose indexes correspond to the elements of the generated permutation. This technique is described, and proven to generate random samples here

        Specified by:
        nextSample in interface RandomData
        Parameters:
        c - the collection to be sampled
        k - the size of the sample
        Returns:
        a random sample of k elements from c
        Throws:
        NotStrictlyPositiveException - if k <= 0.
        NumberIsTooLargeException - if k > c.size().

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