public class HypergeometricDistribution extends AbstractIntegerDistribution
random, randomData
Constructor and Description |
---|
HypergeometricDistribution(int populationSize,
int numberOfSuccesses,
int sampleSize)
Construct a new hypergeometric distribution with the specified population
size, number of successes in the population, and sample size.
|
HypergeometricDistribution(RandomGenerator rng,
int populationSize,
int numberOfSuccesses,
int sampleSize)
Creates a new hypergeometric distribution.
|
Modifier and Type | Method and Description |
---|---|
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) . |
int |
getNumberOfSuccesses()
Access the number of successes.
|
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 |
getPopulationSize()
Access the population size.
|
int |
getSampleSize()
Access the sample size.
|
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 |
logProbability(int x)
For a random variable
X whose values are distributed according to
this distribution, this method returns log(P(X = x)) , where
log is the natural logarithm. |
double |
probability(int x)
For a random variable
X whose values are distributed according
to this distribution, this method returns P(X = x) . |
double |
upperCumulativeProbability(int x)
For this distribution,
X , this method returns P(X >= x) . |
cumulativeProbability, inverseCumulativeProbability, reseedRandomGenerator, sample, sample, solveInverseCumulativeProbability
public HypergeometricDistribution(int populationSize, int numberOfSuccesses, int sampleSize) throws NotPositiveException, NotStrictlyPositiveException, NumberIsTooLargeException
Note: this constructor will implicitly create an instance of
Well19937c
as random generator to be used for sampling only (see
AbstractIntegerDistribution.sample()
and AbstractIntegerDistribution.sample(int)
). In case no sampling is
needed for the created distribution, it is advised to pass null
as random generator via the appropriate constructors to avoid the
additional initialisation overhead.
populationSize
- Population size.numberOfSuccesses
- Number of successes in the population.sampleSize
- Sample size.NotPositiveException
- if numberOfSuccesses < 0
.NotStrictlyPositiveException
- if populationSize <= 0
.NumberIsTooLargeException
- if numberOfSuccesses > populationSize
,
or sampleSize > populationSize
.public HypergeometricDistribution(RandomGenerator rng, int populationSize, int numberOfSuccesses, int sampleSize) throws NotPositiveException, NotStrictlyPositiveException, NumberIsTooLargeException
rng
- Random number generator.populationSize
- Population size.numberOfSuccesses
- Number of successes in the population.sampleSize
- Sample size.NotPositiveException
- if numberOfSuccesses < 0
.NotStrictlyPositiveException
- if populationSize <= 0
.NumberIsTooLargeException
- if numberOfSuccesses > populationSize
,
or sampleSize > populationSize
.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 evaluatedx
public int getNumberOfSuccesses()
public int getPopulationSize()
public int getSampleSize()
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 evaluatedx
public double logProbability(int x)
X
whose values are distributed according to
this distribution, this method returns log(P(X = x))
, where
log
is the natural logarithm. In other words, this method
represents the logarithm of the probability mass function (PMF) for the
distribution. Note that due to the floating point precision and
under/overflow issues, this method will for some distributions be more
precise and faster than computing the logarithm of
IntegerDistribution.probability(int)
.
The default implementation simply computes the logarithm of probability(x)
.
logProbability
in class AbstractIntegerDistribution
x
- the point at which the PMF is evaluatedx
public double upperCumulativeProbability(int x)
X
, this method returns P(X >= x)
.x
- Value at which the CDF is evaluated.public double getNumericalMean()
N
, number of successes m
, and sample
size n
, the mean is n * m / N
.Double.NaN
if it is not definedpublic double getNumericalVariance()
N
, number of successes m
, and sample
size n
, the variance is
[n * m * (N - n) * (N - m)] / [N^2 * (N - 1)]
.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}
.
N
, number of successes m
, and sample
size n
, the lower bound of the support is
max(0, n + m - N)
.public int getSupportUpperBound()
inverseCumulativeProbability(1)
. In other words, this
method must return
inf {x in R | P(X <= x) = 1}
.
m
and sample size n
, the upper
bound of the support is min(m, n)
.public boolean isSupportConnected()
true
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