org.jaitools.numeric

Class MeanVarianceProcessor

java.lang.Object

org.jaitools.numeric.AbstractProcessor

org.jaitools.numeric.MeanVarianceProcessor

All Implemented Interfaces:

Processor

public class MeanVarianceProcessor
extends AbstractProcessor

A Processor to calculate running mean and variance. The algorithm used is that of Welford (1962) which was presented by Knuth:

Donald E. Knuth (1998). The Art of Computer Programming, volume 2: Seminumerical Algorithms, 3rd edn., p. 232.

The algorithm is described online at:

http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#On-line_algorithm

Since:

1.0

Version:

$Id$

Author:

Michael Bedward

See Also:

Statistic, StreamingSampleStats

Field Summary

Fields inherited from class org.jaitools.numeric.AbstractProcessor

numAccepted, numNaN, numNoData, numOffered

Constructor Summary

Constructors

Constructor and Description
MeanVarianceProcessor()

Method Summary

Modifier and Type	Method and Description
Double	get(Statistic stat) Gets the value of the statistic calculated by this processor.
Collection<Statistic>	getSupported() Gets the Statistics supported by this processor.
protected boolean	update(Double sample) Processes a sample value.

Methods inherited from class org.jaitools.numeric.AbstractProcessor

addNoDataRange, addNoDataValue, addRange, addRange, get, getNoDataRanges, getNumAccepted, getNumNaN, getNumNoData, getNumOffered, getRanges, getRangesType, isAccepted, offer, setRangesType

Methods inherited from class java.lang.Object

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

Constructor Detail

MeanVarianceProcessor

public MeanVarianceProcessor()

Method Detail

getSupported

public Collection<Statistic> getSupported()

Gets the Statistics supported by this processor.

Returns:

supported Statistics

update

protected boolean update(Double sample)

Processes a sample value.

Specified by:

update in class AbstractProcessor

Parameters:

sample - the sample value

Returns:

true if the sample is accepted; false otherwise

get

public Double get(Statistic stat)

Gets the value of the statistic calculated by this processor.

Parameters:

stat - the specified statistic

Returns:

the value of the statistic if it has been calculated or Double.NaN otherwise