gov.sandia.cognition.statistics.distribution
Class WeibullDistribution

java.lang.Object
  extended by gov.sandia.cognition.util.AbstractCloneableSerializable
      extended by gov.sandia.cognition.statistics.AbstractDistribution<NumberType>
          extended by gov.sandia.cognition.statistics.AbstractClosedFormUnivariateDistribution<Double>
              extended by gov.sandia.cognition.statistics.AbstractClosedFormSmoothUnivariateDistribution
                  extended by gov.sandia.cognition.statistics.distribution.WeibullDistribution
All Implemented Interfaces:
Vectorizable, ClosedFormComputableDistribution<Double>, ClosedFormDistribution<Double>, ClosedFormUnivariateDistribution<Double>, ComputableDistribution<Double>, Distribution<Double>, DistributionWithMean<Double>, SmoothUnivariateDistribution, UnivariateDistribution<Double>, CloneableSerializable, Serializable, Cloneable
Direct Known Subclasses:
WeibullDistribution.CDF, WeibullDistribution.PDF

@PublicationReference(author="Wikipedia",
                      title="Weibull Distribution",
                      type=WebPage,
                      year=2010,
                      url="http://en.wikipedia.org/wiki/Weibull_distribution")
public class WeibullDistribution
extends AbstractClosedFormSmoothUnivariateDistribution

Describes a Weibull distribution, which is often used to describe the mortality, lifespan, or size distribution of objects.

Since:
3.0
Author:
Kevin R. Dixon
See Also:
Serialized Form

Nested Class Summary
static class WeibullDistribution.CDF
          CDF of the Weibull distribution
static class WeibullDistribution.PDF
          PDF of the Weibull distribution
 
Field Summary
static double DEFAULT_SCALE
          Default scale, 1.0
static double DEFAULT_SHAPE
          Default shape, 1.0.
protected  double scale
          Scale parameter, must be greater than 0.0
protected  double shape
          Shape parameter, must be greater than 0.0
 
Constructor Summary
WeibullDistribution()
          Creates a new instance of WeibullDistribution
WeibullDistribution(double shape, double scale)
          Creates a new instance of WeibullDistribution
WeibullDistribution(WeibullDistribution other)
          Copy constructor
 
Method Summary
 WeibullDistribution clone()
          This makes public the clone method on the Object class and removes the exception that it throws.
 void convertFromVector(Vector parameters)
          Converts the object from a Vector of parameters.
 Vector convertToVector()
          Converts the object to a vector.
 WeibullDistribution.CDF getCDF()
          Gets the CDF of a scalar distribution.
 Double getMaxSupport()
          Gets the minimum support (domain or input) of the distribution.
 Double getMean()
          Gets the arithmetic mean, or "first central moment" or "expectation", of the distribution.
 Double getMinSupport()
          Gets the minimum support (domain or input) of the distribution.
 WeibullDistribution.PDF getProbabilityFunction()
          Gets the distribution function associated with this Distribution, either the PDF or PMF.
 double getScale()
          Getter for scale
 double getShape()
          Getter for shape
 double getVariance()
          Gets the variance of the distribution.
 ArrayList<Double> sample(Random random, int numSamples)
          Draws multiple random samples from the distribution.
 void setScale(double scale)
          Setter for scale
 void setShape(double shape)
          Setter for shape
 
Methods inherited from class gov.sandia.cognition.statistics.AbstractDistribution
sample
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface gov.sandia.cognition.statistics.Distribution
sample
 

Field Detail

DEFAULT_SHAPE

public static final double DEFAULT_SHAPE
Default shape, 1.0.

See Also:
Constant Field Values

DEFAULT_SCALE

public static final double DEFAULT_SCALE
Default scale, 1.0

See Also:
Constant Field Values

shape

protected double shape
Shape parameter, must be greater than 0.0


scale

protected double scale
Scale parameter, must be greater than 0.0

Constructor Detail

WeibullDistribution

public WeibullDistribution()
Creates a new instance of WeibullDistribution


WeibullDistribution

public WeibullDistribution(double shape,
                           double scale)
Creates a new instance of WeibullDistribution

Parameters:
shape - Shape parameter, must be greater than 0.0
scale - Scale parameter, must be greater than 0.0

WeibullDistribution

public WeibullDistribution(WeibullDistribution other)
Copy constructor

Parameters:
other - WeibullDistribution to copy
Method Detail

clone

public WeibullDistribution clone()
Description copied from class: AbstractCloneableSerializable
This makes public the clone method on the Object class and removes the exception that it throws. Its default behavior is to automatically create a clone of the exact type of object that the clone is called on and to copy all primitives but to keep all references, which means it is a shallow copy. Extensions of this class may want to override this method (but call super.clone() to implement a "smart copy". That is, to target the most common use case for creating a copy of the object. Because of the default behavior being a shallow copy, extending classes only need to handle fields that need to have a deeper copy (or those that need to be reset). Some of the methods in ObjectUtil may be helpful in implementing a custom clone method. Note: The contract of this method is that you must use super.clone() as the basis for your implementation.

Specified by:
clone in interface Vectorizable
Specified by:
clone in interface CloneableSerializable
Overrides:
clone in class AbstractClosedFormUnivariateDistribution<Double>
Returns:
A clone of this object.

getShape

public double getShape()
Getter for shape

Returns:
Shape parameter, must be greater than 0.0

setShape

public void setShape(double shape)
Setter for shape

Parameters:
shape - Shape parameter, must be greater than 0.0

getScale

public double getScale()
Getter for scale

Returns:
Scale parameter, must be greater than 0.0

setScale

public void setScale(double scale)
Setter for scale

Parameters:
scale - Scale parameter, must be greater than 0.0

getMean

public Double getMean()
Description copied from interface: DistributionWithMean
Gets the arithmetic mean, or "first central moment" or "expectation", of the distribution.

Returns:
Mean of the distribution.

getVariance

public double getVariance()
Description copied from interface: UnivariateDistribution
Gets the variance of the distribution. This is sometimes called the second central moment by more pedantic people, which is equivalent to the square of the standard deviation.

Returns:
Variance of the distribution.

sample

public ArrayList<Double> sample(Random random,
                                int numSamples)
Description copied from interface: Distribution
Draws multiple random samples from the distribution. It is generally more efficient to use this multiple-sample method than multiple calls of the single-sample method. (But not always.)

Parameters:
random - Random-number generator to use in order to generate random numbers.
numSamples - Number of samples to draw from the distribution.
Returns:
Samples drawn according to this distribution.

convertToVector

public Vector convertToVector()
Description copied from interface: Vectorizable
Converts the object to a vector.

Returns:
The Vector form of the object.

convertFromVector

public void convertFromVector(Vector parameters)
Description copied from interface: Vectorizable
Converts the object from a Vector of parameters.

Parameters:
parameters - The parameters to incorporate.

getMinSupport

public Double getMinSupport()
Description copied from interface: UnivariateDistribution
Gets the minimum support (domain or input) of the distribution.

Returns:
Minimum support.

getMaxSupport

public Double getMaxSupport()
Description copied from interface: UnivariateDistribution
Gets the minimum support (domain or input) of the distribution.

Returns:
Minimum support.

getProbabilityFunction

public WeibullDistribution.PDF getProbabilityFunction()
Description copied from interface: ComputableDistribution
Gets the distribution function associated with this Distribution, either the PDF or PMF.

Returns:
Distribution function associated with this Distribution.

getCDF

public WeibullDistribution.CDF getCDF()
Description copied from interface: UnivariateDistribution
Gets the CDF of a scalar distribution.

Returns:
CDF of the scalar distribution.