org.conqat.lib.commons.math

Class VarianceAggregator

java.lang.Object

org.conqat.lib.commons.math.VarianceAggregator

All Implemented Interfaces:

IAggregator

public class VarianceAggregator
extends java.lang.Object
implements IAggregator

Calculates the variance with a two-pass algorithm. Implementation is highly similar to the one used in Apache Commons.

Constructor Summary

Constructors

Constructor and Description
VarianceAggregator(boolean sample) Constructor.

Method Summary

Modifier and Type	Method and Description
double	aggregate(java.util.Collection<? extends java.lang.Number> values) Aggregates by finding the average value
double	getNeutralElement() Returns Double.NaN.

Methods inherited from class java.lang.Object

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

Constructor Detail

VarianceAggregator

public VarianceAggregator(boolean sample)

Constructor.

Parameters:

sample - if true sample variance is calculated, population variance otherwise.

Method Detail

aggregate

public double aggregate(java.util.Collection<? extends java.lang.Number> values)

Aggregates by finding the average value

Specified by:

aggregate in interface IAggregator

Returns:

Double.NaN for empty input collection

getNeutralElement

public double getNeutralElement()

Returns Double.NaN.

Specified by:

getNeutralElement in interface IAggregator