net.sf.jagg
Class CovariancePopAggregator

java.lang.Object
  net.sf.jagg.Aggregator
      net.sf.jagg.TwoPropAggregator
          net.sf.jagg.AbstractCovarianceAggregator
              net.sf.jagg.CovariancePopAggregator

public class CovariancePopAggregator
extends AbstractCovarianceAggregator

This class represents the "population covariance" aggregator over two sets of numeric values.

Since:

0.1.0

Author:

Randy Gettman

Field Summary

Fields inherited from class net.sf.jagg.AbstractCovarianceAggregator

myCount, mySum1, mySum2, myVarNumerator

Fields inherited from class net.sf.jagg.Aggregator

PROP_SELF

Constructor Summary

CovariancePopAggregator(java.lang.String properties)
Constructs a CovariancePopAggregator on the specified properties, in the format: property, property2.

CovariancePopAggregator(java.lang.String property, java.lang.String property2)
Constructs a CovariancePopAggregator that operates on the specified properties.

Method Summary

CovariancePopAggregator	replicate() Returns an uninitialized copy of this Aggregator object, with the same property(ies) to analyze.
java.lang.Double	terminate() Return the population covariance by dividing the variance numerator by n, where n is the number of non-null pairs of numbers present in the aggregation.
DoubleDouble	terminateDoubleDouble() Return the result as a DoubleDouble.

Methods inherited from class net.sf.jagg.AbstractCovarianceAggregator

init, iterate, merge

Methods inherited from class net.sf.jagg.TwoPropAggregator

getProperty2, setProperty, toString

Methods inherited from class net.sf.jagg.Aggregator

equals, getAggregator, getAggregator, getProperty, getValueFromProperty, hashCode, isInUse, setInUse

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CovariancePopAggregator

public CovariancePopAggregator(java.lang.String properties)

Constructs a CovariancePopAggregator on the specified properties, in the format: property, property2.

Parameters:

properties - A specification string in the format: property, property2.

CovariancePopAggregator

public CovariancePopAggregator(java.lang.String property,
                               java.lang.String property2)

Constructs a CovariancePopAggregator that operates on the specified properties.

Parameters:

property - Determine the population covariance of this property with the other.

property2 - Determine the population covariance of this property with the other.

Method Detail

replicate

public CovariancePopAggregator replicate()

Returns an uninitialized copy of this Aggregator object, with the same property(ies) to analyze.

Specified by:

replicate in class Aggregator

Returns:

An uninitialized copy of this Aggregator object.

terminate

public java.lang.Double terminate()

Return the population covariance by dividing the variance numerator by n, where n is the number of non-null pairs of numbers present in the aggregation.

Specified by:

terminate in class Aggregator

Returns:

The population covariance as a Double, NaN if no values have been accumulated, or 0 if exactly one value has been accumulated.

terminateDoubleDouble

public DoubleDouble terminateDoubleDouble()

Return the result as a DoubleDouble. This is used mainly when other Aggregators that use this result must maintain a high precision.

Overrides:

terminateDoubleDouble in class Aggregator

Returns:

The population covariance as a DoubleDouble, NaN if no values have been accumulated, or 0 if exactly one value has been accumulated.

Since:

0.4.0

See Also:

DoubleDouble