public class AggregateSummaryStatistics extends Object implements StatisticalSummary, Serializable
An aggregator for SummaryStatistics
from several data sets or
data set partitions. In its simplest usage mode, the client creates an
instance via the zeroargument constructor, then uses
createContributingStatistics()
to obtain a SummaryStatistics
for each individual data set / partition. The perset statistics objects
are used as normal, and at any time the aggregate statistics for all the
contributors can be obtained from this object.
Clients with specialized requirements can use alternative constructors to
control the statistics implementations and initial values used by the
contributing and the internal aggregate SummaryStatistics
objects.
A static aggregate(Collection)
method is also included that computes
aggregate statistics directly from a Collection of SummaryStatistics instances.
When createContributingStatistics()
is used to create SummaryStatistics
instances to be aggregated concurrently, the created instances'
SummaryStatistics.addValue(double)
methods must synchronize on the aggregating
instance maintained by this class. In multithreaded environments, if the functionality
provided by aggregate(Collection)
is adequate, that method should be used
to avoid unnecessary computation and synchronization delays.
Constructor and Description 

AggregateSummaryStatistics()
Initializes a new AggregateSummaryStatistics with default statistics
implementations.

AggregateSummaryStatistics(SummaryStatistics prototypeStatistics)
Initializes a new AggregateSummaryStatistics with the specified statistics
object as a prototype for contributing statistics and for the internal
aggregate statistics.

AggregateSummaryStatistics(SummaryStatistics prototypeStatistics,
SummaryStatistics initialStatistics)
Initializes a new AggregateSummaryStatistics with the specified statistics
object as a prototype for contributing statistics and for the internal
aggregate statistics.

Modifier and Type  Method and Description 

static StatisticalSummaryValues 
aggregate(Collection<SummaryStatistics> statistics)
Computes aggregate summary statistics.

SummaryStatistics 
createContributingStatistics()
Creates and returns a
SummaryStatistics whose data will be
aggregated with those of this AggregateSummaryStatistics . 
double 
getGeometricMean()
Returns the geometric mean of all the aggregated data.

double 
getMax()
Returns the maximum of the available values

double 
getMean()
Returns the
arithmetic mean of the available values

double 
getMin()
Returns the minimum of the available values

long 
getN()
Returns the number of available values

double 
getSecondMoment()
Returns a statistic related to the Second Central Moment.

double 
getStandardDeviation()
Returns the standard deviation of the available values.

double 
getSum()
Returns the sum of the values that have been added to Univariate.

StatisticalSummary 
getSummary()
Return a
StatisticalSummaryValues instance reporting current
aggregate statistics. 
double 
getSumOfLogs()
Returns the sum of the logs of all the aggregated data.

double 
getSumsq()
Returns the sum of the squares of all the aggregated data.

double 
getVariance()
Returns the variance of the available values.

public AggregateSummaryStatistics()
public AggregateSummaryStatistics(SummaryStatistics prototypeStatistics)
prototypeStatistics
 a SummaryStatistics
serving as a
prototype both for the internal aggregate statistics and for
contributing statistics obtained via the
createContributingStatistics()
method. Being a prototype
means that other objects are initialized by copying this object's state.
If null
, a new, default statistics object is used. Any statistic
values in the prototype are propagated to contributing statistics
objects and (once) into these aggregate statistics.createContributingStatistics()
public AggregateSummaryStatistics(SummaryStatistics prototypeStatistics, SummaryStatistics initialStatistics)
prototypeStatistics
 a SummaryStatistics
serving as a
prototype both for the internal aggregate statistics and for
contributing statistics obtained via the
createContributingStatistics()
method. Being a prototype
means that other objects are initialized by copying this object's state.
If null
, a new, default statistics object is used. Any statistic
values in the prototype are propagated to contributing statistics
objects, but not into these aggregate statistics.initialStatistics
 a SummaryStatistics
to serve as the
internal aggregate statistics object. If null
, a new, default
statistics object is used.createContributingStatistics()
public double getMax()
getMax
in interface StatisticalSummary
StatisticalSummary.getMax()
public double getMean()
getMean
in interface StatisticalSummary
StatisticalSummary.getMean()
public double getMin()
getMin
in interface StatisticalSummary
StatisticalSummary.getMin()
public long getN()
getN
in interface StatisticalSummary
StatisticalSummary.getN()
public double getStandardDeviation()
getStandardDeviation
in interface StatisticalSummary
StatisticalSummary.getStandardDeviation()
public double getSum()
getSum
in interface StatisticalSummary
StatisticalSummary.getSum()
public double getVariance()
getVariance
in interface StatisticalSummary
StatisticalSummary.getVariance()
public double getSumOfLogs()
SummaryStatistics.getSumOfLogs()
public double getGeometricMean()
SummaryStatistics.getGeometricMean()
public double getSumsq()
SummaryStatistics.getSumsq()
public double getSecondMoment()
SummaryStatistics.getSecondMoment()
public StatisticalSummary getSummary()
StatisticalSummaryValues
instance reporting current
aggregate statistics.public SummaryStatistics createContributingStatistics()
SummaryStatistics
whose data will be
aggregated with those of this AggregateSummaryStatistics
.SummaryStatistics
whose data will be aggregated with
those of this AggregateSummaryStatistics
. The initial state
is a copy of the configured prototype statistics.public static StatisticalSummaryValues aggregate(Collection<SummaryStatistics> statistics)
Returns null if the collection is empty or null.
statistics
 collection of SummaryStatistics to aggregateCopyright © 20032012 The Apache Software Foundation. All Rights Reserved.