Class AggregateSummaryStatistics
 java.lang.Object

 org.apache.commons.math.stat.descriptive.AggregateSummaryStatistics

 All Implemented Interfaces:
Serializable
,StatisticalSummary
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 usescreateContributingStatistics()
to obtain aSummaryStatistics
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 byaggregate(Collection)
is adequate, that method should be used to avoid unecessary computation and synchronization delays. Since:
 2.0
 See Also:
 Serialized Form


Constructor Summary
Constructors Constructor 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.

Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static StatisticalSummaryValues
aggregate(Collection<SummaryStatistics> statistics)
Computes aggregate summary statistics.SummaryStatistics
createContributingStatistics()
Creates and returns aSummaryStatistics
whose data will be aggregated with those of thisAggregateSummaryStatistics
.double
getGeometricMean()
Returns the geometric mean of all the aggregated data.double
getMax()
Returns the maximum of the available valuesdouble
getMean()
Returns the arithmetic mean of the available valuesdouble
getMin()
Returns the minimum of the available valueslong
getN()
Returns the number of available valuesdouble
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 aStatisticalSummaryValues
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.



Constructor Detail

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

AggregateSummaryStatistics
public AggregateSummaryStatistics(SummaryStatistics prototypeStatistics)
Initializes a new AggregateSummaryStatistics with the specified statistics object as a prototype for contributing statistics and for the internal aggregate statistics. This provides for customized statistics implementations to be used by contributing and aggregate statistics. Parameters:
prototypeStatistics
 aSummaryStatistics
serving as a prototype both for the internal aggregate statistics and for contributing statistics obtained via thecreateContributingStatistics()
method. Being a prototype means that other objects are initialized by copying this object's state. Ifnull
, 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. See Also:
createContributingStatistics()

AggregateSummaryStatistics
public 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. This provides for different statistics implementations to be used by contributing and aggregate statistics and for an initial state to be supplied for the aggregate statistics. Parameters:
prototypeStatistics
 aSummaryStatistics
serving as a prototype both for the internal aggregate statistics and for contributing statistics obtained via thecreateContributingStatistics()
method. Being a prototype means that other objects are initialized by copying this object's state. Ifnull
, 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
 aSummaryStatistics
to serve as the internal aggregate statistics object. Ifnull
, a new, default statistics object is used. See Also:
createContributingStatistics()


Method Detail

getMax
public double getMax()
Returns the maximum of the available values. This version returns the maximum over all the aggregated data. Specified by:
getMax
in interfaceStatisticalSummary
 Returns:
 The max or Double.NaN if no values have been added.
 See Also:
StatisticalSummary.getMax()

getMean
public double getMean()
Returns the arithmetic mean of the available values. This version returns the mean of all the aggregated data. Specified by:
getMean
in interfaceStatisticalSummary
 Returns:
 The mean or Double.NaN if no values have been added.
 See Also:
StatisticalSummary.getMean()

getMin
public double getMin()
Returns the minimum of the available values. This version returns the minimum over all the aggregated data. Specified by:
getMin
in interfaceStatisticalSummary
 Returns:
 The min or Double.NaN if no values have been added.
 See Also:
StatisticalSummary.getMin()

getN
public long getN()
Returns the number of available values. This version returns a count of all the aggregated data. Specified by:
getN
in interfaceStatisticalSummary
 Returns:
 The number of available values
 See Also:
StatisticalSummary.getN()

getStandardDeviation
public double getStandardDeviation()
Returns the standard deviation of the available values.. This version returns the standard deviation of all the aggregated data. Specified by:
getStandardDeviation
in interfaceStatisticalSummary
 Returns:
 The standard deviation, Double.NaN if no values have been added or 0.0 for a single value set.
 See Also:
StatisticalSummary.getStandardDeviation()

getSum
public double getSum()
Returns the sum of the values that have been added to Univariate.. This version returns a sum of all the aggregated data. Specified by:
getSum
in interfaceStatisticalSummary
 Returns:
 The sum or Double.NaN if no values have been added
 See Also:
StatisticalSummary.getSum()

getVariance
public double getVariance()
Returns the variance of the available values.. This version returns the variance of all the aggregated data. Specified by:
getVariance
in interfaceStatisticalSummary
 Returns:
 The variance, Double.NaN if no values have been added or 0.0 for a single value set.
 See Also:
StatisticalSummary.getVariance()

getSumOfLogs
public double getSumOfLogs()
Returns the sum of the logs of all the aggregated data. Returns:
 the sum of logs
 See Also:
SummaryStatistics.getSumOfLogs()

getGeometricMean
public double getGeometricMean()
Returns the geometric mean of all the aggregated data. Returns:
 the geometric mean
 See Also:
SummaryStatistics.getGeometricMean()

getSumsq
public double getSumsq()
Returns the sum of the squares of all the aggregated data. Returns:
 The sum of squares
 See Also:
SummaryStatistics.getSumsq()

getSecondMoment
public double getSecondMoment()
Returns a statistic related to the Second Central Moment. Specifically, what is returned is the sum of squared deviations from the sample mean among the all of the aggregated data. Returns:
 second central moment statistic
 See Also:
SummaryStatistics.getSecondMoment()

getSummary
public StatisticalSummary getSummary()
Return aStatisticalSummaryValues
instance reporting current aggregate statistics. Returns:
 Current values of aggregate statistics

createContributingStatistics
public SummaryStatistics createContributingStatistics()
Creates and returns aSummaryStatistics
whose data will be aggregated with those of thisAggregateSummaryStatistics
. Returns:
 a
SummaryStatistics
whose data will be aggregated with those of thisAggregateSummaryStatistics
. The initial state is a copy of the configured prototype statistics.

aggregate
public static StatisticalSummaryValues aggregate(Collection<SummaryStatistics> statistics)
Computes aggregate summary statistics. This method can be used to combine statistics computed over partitions or subsamples  i.e., the StatisticalSummaryValues returned should contain the same values that would have been obtained by computing a single StatisticalSummary over the combined dataset.Returns null if the collection is empty or null.
 Parameters:
statistics
 collection of SummaryStatistics to aggregate Returns:
 summary statistics for the combined dataset

