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java.lang.Object org.apache.commons.math3.distribution.AbstractIntegerDistribution org.apache.commons.math3.distribution.ZipfDistribution
public class ZipfDistribution
Implementation of the Zipf distribution.
Field Summary |
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Fields inherited from class org.apache.commons.math3.distribution.AbstractIntegerDistribution |
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random, randomData |
Constructor Summary | |
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ZipfDistribution(int numberOfElements,
double exponent)
Create a new Zipf distribution with the given number of elements and exponent. |
|
ZipfDistribution(RandomGenerator rng,
int numberOfElements,
double exponent)
Creates a Zipf distribution. |
Method Summary | |
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protected double |
calculateNumericalMean()
Used by getNumericalMean() . |
protected double |
calculateNumericalVariance()
Used by getNumericalVariance() . |
double |
cumulativeProbability(int x)
For a random variable X whose values are distributed according
to this distribution, this method returns P(X <= x) . |
double |
getExponent()
Get the exponent characterizing the distribution. |
int |
getNumberOfElements()
Get the number of elements (e.g. |
double |
getNumericalMean()
Use this method to get the numerical value of the mean of this distribution. |
double |
getNumericalVariance()
Use this method to get the numerical value of the variance of this distribution. |
int |
getSupportLowerBound()
Access the lower bound of the support. |
int |
getSupportUpperBound()
Access the upper bound of the support. |
boolean |
isSupportConnected()
Use this method to get information about whether the support is connected, i.e. |
double |
probability(int x)
For a random variable X whose values are distributed according
to this distribution, this method returns P(X = x) . |
Methods inherited from class org.apache.commons.math3.distribution.AbstractIntegerDistribution |
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cumulativeProbability, inverseCumulativeProbability, reseedRandomGenerator, sample, sample, solveInverseCumulativeProbability |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ZipfDistribution(int numberOfElements, double exponent)
numberOfElements
- Number of elements.exponent
- Exponent.
NotStrictlyPositiveException
- if numberOfElements <= 0
or exponent <= 0
.public ZipfDistribution(RandomGenerator rng, int numberOfElements, double exponent) throws NotStrictlyPositiveException
rng
- Random number generator.numberOfElements
- Number of elements.exponent
- Exponent.
NotStrictlyPositiveException
- if numberOfElements <= 0
or exponent <= 0
.Method Detail |
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public int getNumberOfElements()
public double getExponent()
public double probability(int x)
X
whose values are distributed according
to this distribution, this method returns P(X = x)
. In other
words, this method represents the probability mass function (PMF)
for the distribution.
x
- the point at which the PMF is evaluated
x
public double cumulativeProbability(int x)
X
whose values are distributed according
to this distribution, this method returns P(X <= x)
. In other
words, this method represents the (cumulative) distribution function
(CDF) for this distribution.
x
- the point at which the CDF is evaluated
x
public double getNumericalMean()
N
and exponent s
, the mean is
Hs1 / Hs
, where
Hs1 = generalizedHarmonic(N, s - 1)
,Hs = generalizedHarmonic(N, s)
.
Double.NaN
if it is not definedprotected double calculateNumericalMean()
getNumericalMean()
.
public double getNumericalVariance()
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)
.
Double.POSITIVE_INFINITY
or
Double.NaN
if it is not defined)protected double calculateNumericalVariance()
getNumericalVariance()
.
public int getSupportLowerBound()
inverseCumulativeProbability(0)
. In other words, this
method must return
inf {x in Z | P(X <= x) > 0}
.
public int getSupportUpperBound()
inverseCumulativeProbability(1)
. In other words, this
method must return
inf {x in R | P(X <= x) = 1}
.
public boolean isSupportConnected()
true
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