org.apache.commons.math.stat.descriptive

Class SynchronizedDescriptiveStatistics

java.lang.Object

org.apache.commons.math.stat.descriptive.DescriptiveStatistics

org.apache.commons.math.stat.descriptive.SynchronizedDescriptiveStatistics

All Implemented Interfaces:

java.io.Serializable, StatisticalSummary

public class SynchronizedDescriptiveStatistics
extends DescriptiveStatistics

Implementation of DescriptiveStatistics that is safe to use in a multithreaded environment. Multiple threads can safely operate on a single instance without causing runtime exceptions due to race conditions. In effect, this implementation makes modification and access methods atomic operations for a single instance. That is to say, as one thread is computing a statistic from the instance, no other thread can modify the instance nor compute another statistic.

Since:

1.2

Version:

$Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private static long	serialVersionUID Serialization UID

Fields inherited from class org.apache.commons.math.stat.descriptive.DescriptiveStatistics

eDA, INFINITE_WINDOW, windowSize

Constructor Summary

Constructors

Constructor and Description
SynchronizedDescriptiveStatistics() Construct an instance with infinite window
SynchronizedDescriptiveStatistics(int window) Construct an instance with finite window
SynchronizedDescriptiveStatistics(SynchronizedDescriptiveStatistics original) A copy constructor.

Method Summary

Modifier and Type	Method and Description
void	addValue(double v) Adds the value to the dataset.
double	apply(UnivariateStatistic stat) Apply the given statistic to the data associated with this set of statistics.
void	clear() Resets all statistics and storage
SynchronizedDescriptiveStatistics	copy() Returns a copy of this SynchronizedDescriptiveStatistics instance with the same internal state.
static void	copy(SynchronizedDescriptiveStatistics source, SynchronizedDescriptiveStatistics dest) Copies source to dest.
double	getElement(int index) Returns the element at the specified index
long	getN() Returns the number of available values
double	getStandardDeviation() Returns the standard deviation of the available values.
double[]	getValues() Returns the current set of values in an array of double primitives.
int	getWindowSize() Returns the maximum number of values that can be stored in the dataset, or INFINITE_WINDOW (-1) if there is no limit.
void	setWindowSize(int windowSize) WindowSize controls the number of values which contribute to the reported statistics.
java.lang.String	toString() Generates a text report displaying univariate statistics from values that have been added.

Methods inherited from class org.apache.commons.math.stat.descriptive.DescriptiveStatistics

copy, getGeometricMean, getGeometricMeanImpl, getKurtosis, getKurtosisImpl, getMax, getMaxImpl, getMean, getMeanImpl, getMin, getMinImpl, getPercentile, getPercentileImpl, getSkewness, getSkewnessImpl, getSortedValues, getSum, getSumImpl, getSumsq, getSumsqImpl, getVariance, getVarianceImpl, removeMostRecentValue, replaceMostRecentValue, setGeometricMeanImpl, setKurtosisImpl, setMaxImpl, setMeanImpl, setMinImpl, setPercentileImpl, setSkewnessImpl, setSumImpl, setSumsqImpl, setVarianceImpl

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

Serialization UID

See Also:

Constant Field Values

Constructor Detail

SynchronizedDescriptiveStatistics

public SynchronizedDescriptiveStatistics()

Construct an instance with infinite window

SynchronizedDescriptiveStatistics

public SynchronizedDescriptiveStatistics(int window)

Construct an instance with finite window

Parameters:

window - the finite window size.

SynchronizedDescriptiveStatistics

public SynchronizedDescriptiveStatistics(SynchronizedDescriptiveStatistics original)

A copy constructor. Creates a deep-copy of the original.

Parameters:

original - the SynchronizedDescriptiveStatistics instance to copy

Method Detail

addValue

public void addValue(double v)

Adds the value to the dataset. If the dataset is at the maximum size (i.e., the number of stored elements equals the currently configured windowSize), the first (oldest) element in the dataset is discarded to make room for the new value.

Overrides:

addValue in class DescriptiveStatistics

Parameters:

v - the value to be added

apply

public double apply(UnivariateStatistic stat)

Apply the given statistic to the data associated with this set of statistics.

Overrides:

apply in class DescriptiveStatistics

Parameters:

stat - the statistic to apply

Returns:

the computed value of the statistic.

clear

public void clear()

Resets all statistics and storage

Overrides:

clear in class DescriptiveStatistics

getElement

public double getElement(int index)

Returns the element at the specified index

Overrides:

getElement in class DescriptiveStatistics

Parameters:

index - The Index of the element

Returns:

return the element at the specified index

getN

public long getN()

Returns the number of available values

Specified by:

getN in interface StatisticalSummary

Overrides:

getN in class DescriptiveStatistics

Returns:

The number of available values

getStandardDeviation

public double getStandardDeviation()

Returns the standard deviation of the available values.

Specified by:

getStandardDeviation in interface StatisticalSummary

Overrides:

getStandardDeviation in class DescriptiveStatistics

Returns:

The standard deviation, Double.NaN if no values have been added or 0.0 for a single value set.

getValues

public double[] getValues()

Returns the current set of values in an array of double primitives. The order of addition is preserved. The returned array is a fresh copy of the underlying data -- i.e., it is not a reference to the stored data.

Overrides:

getValues in class DescriptiveStatistics

Returns:

returns the current set of numbers in the order in which they were added to this set

getWindowSize

public int getWindowSize()

Returns the maximum number of values that can be stored in the dataset, or INFINITE_WINDOW (-1) if there is no limit.

Overrides:

getWindowSize in class DescriptiveStatistics

Returns:

The current window size or -1 if its Infinite.

setWindowSize

public void setWindowSize(int windowSize)

WindowSize controls the number of values which contribute to the reported statistics. For example, if windowSize is set to 3 and the values {1,2,3,4,5} have been added in that order then the available values are {3,4,5} and all reported statistics will be based on these values

Overrides:

setWindowSize in class DescriptiveStatistics

Parameters:

windowSize - sets the size of the window.

toString

public java.lang.String toString()

Generates a text report displaying univariate statistics from values that have been added. Each statistic is displayed on a separate line.

Overrides:

toString in class DescriptiveStatistics

Returns:

String with line feeds displaying statistics

copy

public SynchronizedDescriptiveStatistics copy()

Returns a copy of this SynchronizedDescriptiveStatistics instance with the same internal state.

Overrides:

copy in class DescriptiveStatistics

Returns:

a copy of this

copy

public static void copy(SynchronizedDescriptiveStatistics source,
                        SynchronizedDescriptiveStatistics dest)

Copies source to dest.

Neither source nor dest can be null.

Acquires synchronization lock on source, then dest before copying.

Parameters:

source - SynchronizedDescriptiveStatistics to copy

dest - SynchronizedDescriptiveStatistics to copy to

Throws:

java.lang.NullPointerException - if either source or dest is null