Package com.imsl.stat

Class PoissonDistribution

java.lang.Object
com.imsl.stat.PoissonDistribution
All Implemented Interfaces:
Distribution, ProbabilityDistribution, Serializable
public class PoissonDistribution extends Object implements ProbabilityDistribution, Serializable
Evaluates a Poisson probability density of a given set of data.

The poissonDistribution evaluates the Poisson probability density of a given set of data, xData. If parameters are not supplied, the eval method fits the Poisson probability density function by first calculating theta, \(\theta\). The Poisson probability density function is defined as: $$f(x)= \frac{\theta^{x}e^{-\theta}}{x!}\,\,\mbox{,}\,\, x \ge 0\,\,\, \mbox{and}\,\,\, \theta > 0 \mbox{.} $$

The DataMining package class NaiveBayesClassifier uses PoissonDistribution as a method to train continuous data.

See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    PoissonDistribution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    double[]
    eval(double[] xData)
    Fits a Poisson probability distribution to xData and returns the probability density at each value.
    double[]
    eval(double[] xData, Object[] parameters)
    Evaluates a Poisson probability distribution with a given set of parameters at each point in xData and returns the probability density at each value.
    double
    eval(double xData, Object[] parameters)
    Evaluates a Poisson probability density function at a given point xData.
    Object[]
    getParameters()
    Returns the current parameters of the Poisson probability density function.
    double
    getTheta()
    Returns the mean number of successes in a given time period of the Poisson probability distribution.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • PoissonDistribution

      public PoissonDistribution()

  • Method Details

    • eval

      public double[] eval(double[] xData)
      Fits a Poisson probability distribution to xData and returns the probability density at each value.
      Specified by:
      eval in interface Distribution
      Parameters:
      xData - a double array representing the points at which the Poisson probability distribution function is to be evaluated
      Returns:
      a double array representing the Poisson probability density at each value of xData

    • eval

      public double[] eval(double[] xData, Object[] parameters)
      Evaluates a Poisson probability distribution with a given set of parameters at each point in xData and returns the probability density at each value.
      Specified by:
      eval in interface ProbabilityDistribution
      Parameters:
      xData - a double array representing the points at which the Poisson probability distribution function is to be evaluated
      parameters - an Object array representing the parameters used to evaluate the Poisson distribution, see method getParameters.
      Returns:
      a double array representing the Poisson probability density at each value of xData

    • eval

      public double eval(double xData, Object[] parameters)
      Evaluates a Poisson probability density function at a given point xData.
      Specified by:
      eval in interface ProbabilityDistribution
      Parameters:
      xData - a double representing the point at which the Poisson probability distribution function is to be evaluated
      parameters - an Object array representing the parameters used to evaluate the Poisson distribution, see method getParameters
      Returns:
      a double representing the Poisson probability density at xData

    • getParameters

      public Object[] getParameters()
      Returns the current parameters of the Poisson probability density function.
      Specified by:
      getParameters in interface ProbabilityDistribution
      Returns:
      an Object array containing the parameters resulting from the last invocation of the (Distribution) eval method with the following signature, double[] eval(double[] xData). This Object array can be used as input to the eval methods that require an Object array of distribution parameters as input.

    • getTheta

      public double getTheta()
      Returns the mean number of successes in a given time period of the Poisson probability distribution.
      Returns:
      a double representing the mean number of successes in a given time period of the Poisson probability distribution