net.sf.jagg
Class CorrelationAggregator

java.lang.Object
  net.sf.jagg.Aggregator
      net.sf.jagg.TwoPropAggregator
          net.sf.jagg.CorrelationAggregator

public class CorrelationAggregator
extends TwoPropAggregator

This class represents the "coefficient of correlation" aggregator over two sets of numeric values.

Since:

0.1.0

Author:

Randy Gettman

Field Summary

Fields inherited from class net.sf.jagg.Aggregator

PROP_SELF

Constructor Summary

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

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

Method Summary

void	init() Initialize the internal aggregators: a CovarianceAggregator, and 2 VarianceAggregators (one each for both properties).
void	iterate(java.lang.Object value) Iterate the internal aggregators.
void	merge(Aggregator agg) Merge the given Aggregator into this one by merging each individual internal Aggregator.
CorrelationAggregator	replicate() Returns an uninitialized copy of this Aggregator object, with the same property(ies) to analyze.
java.lang.Double	terminate() Return the coefficient of correlation, calculated as follows: CovariancePop(prop1, prop2) / Math.sqrt(VariancePop(prop1) * VariancePop(prop2))
DoubleDouble	terminateDoubleDouble() Return the result as a DoubleDouble.

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

CorrelationAggregator

public CorrelationAggregator(java.lang.String properties)

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

Parameters:

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

CorrelationAggregator

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

Constructs a CorrelationAggregator that operates on the specified properties.

Parameters:

property - Correlate this property with the other.

property2 - Correlate this property with the other.

Method Detail

replicate

public CorrelationAggregator 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.

init

public void init()

Initialize the internal aggregators: a CovarianceAggregator, and 2 VarianceAggregators (one each for both properties).

Specified by:

init in class Aggregator

See Also:

CovarianceAggregator, VarianceAggregator

iterate

public void iterate(java.lang.Object value)

Iterate the internal aggregators.

Specified by:

iterate in class Aggregator

Parameters:

value - The value to aggregate.

See Also:

Aggregator.getValueFromProperty(java.lang.Object, java.lang.String)

merge

public void merge(Aggregator agg)

Merge the given Aggregator into this one by merging each individual internal Aggregator.

Specified by:

merge in class Aggregator

Parameters:

agg - The Aggregator to merge into this one.

terminate

public java.lang.Double terminate()

Return the coefficient of correlation, calculated as follows:
CovariancePop(prop1, prop2) / Math.sqrt(VariancePop(prop1) * VariancePop(prop2))

Specified by:

terminate in class Aggregator

Returns:

The coefficient of correlation as a Double.

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 coefficient of correlation as a DoubleDouble, or NaN if no values have been accumulated or the variance for one of the properties is zero.

Since:

0.4.0

See Also:

DoubleDouble