sdsu.algorithms.data
Class ProbabilityDistribution
java.lang.Object
|
+--sdsu.algorithms.data.ProbabilityDistribution
- Direct Known Subclasses:
- DiscreteProbability
- public abstract class ProbabilityDistribution
- extends java.lang.Object
- implements NumberGenerator
An abstract class defining an interface for probability distributions.
A sample space is the set of events or items of interest. A
probability function on a sample space is map from the sample
space to the interval [0, 1], such that sum of the probabilities of all items
in the space is one. A random variable is a real-valued function defined
over the events in a sample space. The probability function of a random varabiel is
a probability function. The density is a function that assigns
probabilities to allowed ranges of the random variable.
This class and many of its subclasses are adapted from Smalltalk-80: The language
and Its Implementation, Goldberg & Robson, Addison-Wesley, 1983, chapter 21,
pages 417-438.
- Version:
- 1.0 10 June 1997
- Author:
- Roger Whitney (whitney@cs.sdsu.edu)
|
Method Summary |
abstract double |
density(double sampleSpaceItem)
Returns the probability of an item in the sample
space will occur. |
double |
density(java.lang.Number sampleSpaceItem)
|
abstract java.util.Vector |
distribution(java.util.Vector sampleSpaceCollection)
Computes the density of each item in the vector. |
abstract double |
mean()
Returns the mean of the probability distribution |
abstract double |
nextElement()
Returns a ramdon element in the sample space. |
abstract double |
variance()
Returns the variance of the probability distribution |
| Methods inherited from class java.lang.Object |
equals,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
ProbabilityDistribution
public ProbabilityDistribution()
density
public abstract double density(double sampleSpaceItem)
throws OutOfBoundsException
- Returns the probability of an item in the sample
space will occur.
- Parameters:
sampleSpaceItem - item in the sample space for which
the probability of occuring is computed.- Throws:
- OutOfBoundsException - if sampleSpaceItem is not in the
sample space of the distribution.
density
public double density(java.lang.Number sampleSpaceItem)
mean
public abstract double mean()
- Returns the mean of the probability distribution
variance
public abstract double variance()
- Returns the variance of the probability distribution
distribution
public abstract java.util.Vector distribution(java.util.Vector sampleSpaceCollection)
- Computes the density of each item in the vector.
Returns a vector of the densities.
nextElement
public abstract double nextElement()
- Returns a ramdon element in the sample space. The probability of
a given item being returned is determined by the probability
distribution on the sample space.
- Specified by:
- nextElement in interface NumberGenerator