net.sourceforge.jabm.prng
Class DiscreteProbabilityDistribution

java.lang.Object
  net.sourceforge.jabm.prng.DiscreteProbabilityDistribution

All Implemented Interfaces:

java.io.Serializable, Resetable

public class DiscreteProbabilityDistribution
extends java.lang.Object
implements Resetable, java.io.Serializable

A class representing a discrete probability distribution which can used to generate random events according to the specified distribution. The output from a uniform PRNG is used to to select from the different possible events.

See Also:

Serialized Form

Nested Class Summary

class	DiscreteProbabilityDistribution.ProbabilityActionPair
static class	DiscreteProbabilityDistribution.ProbabilityError

Field Summary

protected int	n The number of possible events for this distribution.
protected java.util.TreeSet<DiscreteProbabilityDistribution.ProbabilityActionPair>	p The probability distribution.
protected cern.jet.random.engine.RandomEngine	prng
protected java.util.TreeMap<java.lang.Integer,java.lang.Double>	reverseMap

Constructor Summary

DiscreteProbabilityDistribution(cern.jet.random.engine.RandomEngine prng, double[] p)

DiscreteProbabilityDistribution(cern.jet.random.engine.RandomEngine prng, int n)
Construct a new distribution with k possible events.

Method Summary

double	computeMean() Compute the expected value of the random variable defined by this distribution.
int	generateRandomEvent() Generate a random event according to the probability distribution.
int	getN()
double	getProbability(int i) Get the probability of the ith event.
double	getSum()
void	initialise()
void	initialise(double[] probs)
void	reset() Reinitialise our state to the original settings.
void	setProbability(int i, double probability) Set the probability of the ith event.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

p

protected java.util.TreeSet<DiscreteProbabilityDistribution.ProbabilityActionPair> p

The probability distribution.

reverseMap

protected java.util.TreeMap<java.lang.Integer,java.lang.Double> reverseMap

n

protected int n

The number of possible events for this distribution.

prng

protected cern.jet.random.engine.RandomEngine prng

Constructor Detail

DiscreteProbabilityDistribution

public DiscreteProbabilityDistribution(cern.jet.random.engine.RandomEngine prng,
                                       int n)

Construct a new distribution with k possible events.

Parameters:

k - The number of possible events for this random variable

DiscreteProbabilityDistribution

public DiscreteProbabilityDistribution(cern.jet.random.engine.RandomEngine prng,
                                       double[] p)

Method Detail

initialise

public void initialise()

initialise

public void initialise(double[] probs)

setProbability

public void setProbability(int i,
                           double probability)

Set the probability of the ith event.

Parameters:

i - The event

probability - The probability of event i occuring

getProbability

public double getProbability(int i)

Get the probability of the ith event.

Parameters:

i - The event

generateRandomEvent

public int generateRandomEvent()

Generate a random event according to the probability distribution.

Returns:

An integer value representing one of the possible events.

getSum

public double getSum()

reset

public void reset()

Description copied from interface: Resetable

Reinitialise our state to the original settings.

Specified by:

reset in interface Resetable

computeMean

public double computeMean()

Compute the expected value of the random variable defined by this distribution.

Returns:

The expected value of the distribution

getN

public int getN()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object