ZipfDistributionImpl (Commons Math 2.2 API)

java.lang.Object
- org.apache.commons.math.distribution.AbstractDistribution
- - org.apache.commons.math.distribution.AbstractIntegerDistribution
  - - org.apache.commons.math.distribution.ZipfDistributionImpl

All Implemented Interfaces:

Serializable, DiscreteDistribution, Distribution, IntegerDistribution, ZipfDistribution
```
public class ZipfDistributionImpl
extends AbstractIntegerDistribution
implements ZipfDistribution, Serializable
```
Implementation for the ZipfDistribution.

Version:

$Revision: 1054524 $ $Date: 2011-01-03 05:59:18 +0100 (lun. 03 janv. 2011) $

See Also:
Serialized Form

Field Summary
- Fields inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution
  randomData

Constructor Summary

Constructors
Constructor and Description
`ZipfDistributionImpl(int numberOfElements, double exponent)` Create a new Zipf distribution with the given number of elements and exponent.

Method Summary

Methods
Modifier and Type	Method and Description
`double`	`cumulativeProbability(int x)` The probability distribution function P(X <= x) for a Zipf distribution.
`protected int`	`getDomainLowerBound(double p)` Access the domain value lower bound, based on `p`, used to bracket a PDF root.
`protected int`	`getDomainUpperBound(double p)` Access the domain value upper bound, based on `p`, used to bracket a PDF root.
`double`	`getExponent()` Get the exponent characterising the distribution.
`int`	`getNumberOfElements()` Get the number of elements (e.g.
`protected double`	`getNumericalMean()` Returns the mean.
`protected double`	`getNumericalVariance()` Returns the variance.
`int`	`getSupportLowerBound()` Returns the lower bound of the support for the distribution.
`int`	`getSupportUpperBound()` Returns the upper bound of the support for the distribution.
`double`	`probability(int x)` The probability mass function P(X = x) for a Zipf distribution.
`void`	`setExponent(double s)` Deprecated. as of 2.1 (class will become immutable in 3.0)
`void`	`setNumberOfElements(int n)` Deprecated. as of 2.1 (class will become immutable in 3.0)

Methods inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution
cumulativeProbability, cumulativeProbability, cumulativeProbability, inverseCumulativeProbability, isSupportLowerBoundInclusive, isSupportUpperBoundInclusive, probability, reseedRandomGenerator, sample, sample

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.commons.math.distribution.IntegerDistribution
cumulativeProbability, inverseCumulativeProbability

Methods inherited from interface org.apache.commons.math.distribution.DiscreteDistribution
probability

Methods inherited from interface org.apache.commons.math.distribution.Distribution
cumulativeProbability, cumulativeProbability

- Constructor Detail
  - ZipfDistributionImpl
```
public ZipfDistributionImpl(int numberOfElements,
                    double exponent)
                     throws IllegalArgumentException
```
    Create a new Zipf distribution with the given number of elements and exponent. Both values must be positive; otherwise an IllegalArgumentException is thrown.
    
    Parameters:
    numberOfElements - the number of elements
    exponent - the exponent
    
    Throws:
    
    IllegalArgumentException - if n ≤ 0 or s ≤ 0.0
- Method Detail
  - getNumberOfElements
```
public int getNumberOfElements()
```
    Get the number of elements (e.g. corpus size) for the distribution.
    
    Specified by:
    
    getNumberOfElements in interface ZipfDistribution
    
    Returns:
    the number of elements
  - setNumberOfElements
```
@Deprecated
public void setNumberOfElements(int n)
```
    Deprecated. as of 2.1 (class will become immutable in 3.0)
    
    Set the number of elements (e.g. corpus size) for the distribution. The parameter value must be positive; otherwise an IllegalArgumentException is thrown.
    
    Specified by:
    
    setNumberOfElements in interface ZipfDistribution
    
    Parameters:
    n - the number of elements
    
    Throws:
    
    IllegalArgumentException - if n ≤ 0
  - getExponent
```
public double getExponent()
```
    Get the exponent characterising the distribution.
    
    Specified by:
    
    getExponent in interface ZipfDistribution
    
    Returns:
    the exponent
  - setExponent
```
@Deprecated
public void setExponent(double s)
```
    Deprecated. as of 2.1 (class will become immutable in 3.0)
    
    Set the exponent characterising the distribution. The parameter value must be positive; otherwise an IllegalArgumentException is thrown.
    
    Specified by:
    
    setExponent in interface ZipfDistribution
    
    Parameters:
    s - the exponent
    
    Throws:
    
    IllegalArgumentException - if s ≤ 0.0
  - probability
```
public double probability(int x)
```
    The probability mass function P(X = x) for a Zipf distribution.
    
    Specified by:
    
    probability in interface IntegerDistribution
    
    Parameters:
    x - the value at which the probability density function is evaluated.
    
    Returns:
    the value of the probability mass function at x
  - cumulativeProbability
```
public double cumulativeProbability(int x)
```
    The probability distribution function P(X <= x) for a Zipf distribution.
    
    Specified by:
    
    cumulativeProbability in interface IntegerDistribution
    
    Specified by:
    
    cumulativeProbability in class AbstractIntegerDistribution
    
    Parameters:
    x - the value at which the PDF is evaluated.
    
    Returns:
    Zipf distribution function evaluated at x
  - getDomainLowerBound
```
protected int getDomainLowerBound(double p)
```
    Access the domain value lower bound, based on p, used to bracket a PDF root.
    
    Specified by:
    
    getDomainLowerBound in class AbstractIntegerDistribution
    
    Parameters:
    p - the desired probability for the critical value
    
    Returns:
    domain value lower bound, i.e. P(X < lower bound) < p
  - getDomainUpperBound
```
protected int getDomainUpperBound(double p)
```
    Access the domain value upper bound, based on p, used to bracket a PDF root.
    
    Specified by:
    
    getDomainUpperBound in class AbstractIntegerDistribution
    
    Parameters:
    p - the desired probability for the critical value
    
    Returns:
    domain value upper bound, i.e. P(X < upper bound) > p
  - getSupportLowerBound
```
public int getSupportLowerBound()
```
    Returns the lower bound of the support for the distribution. The lower bound of the support is always 1 no matter the parameters.
    
    Returns:
    lower bound of the support (always 1)
    Since:
    
    2.2
  - getSupportUpperBound
```
public int getSupportUpperBound()
```
    Returns the upper bound of the support for the distribution. The upper bound of the support is the number of elements
    
    Returns:
    upper bound of the support
    Since:
    
    2.2
  - getNumericalMean
```
protected double getNumericalMean()
```
    Returns the mean. For number of elements N and exponent s, the mean is Hs1 / Hs where
    - Hs1 = generalizedHarmonic(N, s - 1)
    - Hs = generalizedHarmonic(N, s)
    Returns:
    the mean
    Since:
    
    2.2
  - getNumericalVariance
```
protected double getNumericalVariance()
```
    Returns the variance. For number of elements N and exponent s, the mean is (Hs2 / Hs) - (Hs1^2 / Hs^2) where
    - Hs2 = generalizedHarmonic(N, s - 2)
    - Hs1 = generalizedHarmonic(N, s - 1)
    - Hs = generalizedHarmonic(N, s)
    Returns:
    the variance
    Since:
    
    2.2

Class ZipfDistributionImpl

Field Summary

Fields inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.commons.math.distribution.IntegerDistribution

Methods inherited from interface org.apache.commons.math.distribution.DiscreteDistribution

Methods inherited from interface org.apache.commons.math.distribution.Distribution

Constructor Detail

ZipfDistributionImpl

Method Detail

getNumberOfElements

setNumberOfElements

getExponent

setExponent

probability

cumulativeProbability

getDomainLowerBound

getDomainUpperBound

getSupportLowerBound

getSupportUpperBound

getNumericalMean

getNumericalVariance