org.apache.commons.math.stat.descriptive
Class SummaryStatistics

java.lang.Object
  org.apache.commons.math.stat.descriptive.SummaryStatistics

All Implemented Interfaces:

Serializable, StatisticalSummary

Direct Known Subclasses:

SynchronizedSummaryStatistics

public class SummaryStatistics
extends Object
implements StatisticalSummary, Serializable

Computes summary statistics for a stream of data values added using the addValue method. The data values are not stored in memory, so this class can be used to compute statistics for very large data streams.

The StorelessUnivariateStatistic instances used to maintain summary state and compute statistics are configurable via setters. For example, the default implementation for the variance can be overridden by calling setVarianceImpl(StorelessUnivariateStatistic). Actual parameters to these methods must implement the StorelessUnivariateStatistic interface and configuration must be completed before addValue is called. No configuration is necessary to use the default, commons-math provided implementations.

Note: This class is not thread-safe. Use SynchronizedSummaryStatistics if concurrent access from multiple threads is required.

Version:

$Revision: 1042376 $ $Date: 2010-12-05 16:54:55 +0100 (dim. 05 déc. 2010) $

See Also:

Serialized Form

Field Summary

protected GeometricMean	geoMean geoMean of values that have been added
protected Max	max max of values that have been added
protected Mean	mean mean of values that have been added
protected Min	min min of values that have been added
protected long	n count of values that have been added
protected SecondMoment	secondMoment SecondMoment is used to compute the mean and variance
protected Sum	sum sum of values that have been added
protected SumOfLogs	sumLog sumLog of values that have been added
protected SumOfSquares	sumsq sum of the square of each value that has been added
protected Variance	variance variance of values that have been added

Constructor Summary

SummaryStatistics()
Construct a SummaryStatistics instance

SummaryStatistics(SummaryStatistics original)
A copy constructor.

Method Summary

void	addValue(double value) Add a value to the data
void	clear() Resets all statistics and storage
SummaryStatistics	copy() Returns a copy of this SummaryStatistics instance with the same internal state.
static void	copy(SummaryStatistics source, SummaryStatistics dest) Copies source to dest.
boolean	equals(Object object) Returns true iff object is a SummaryStatistics instance and all statistics have the same values as this.
StorelessUnivariateStatistic	getGeoMeanImpl() Returns the currently configured geometric mean implementation
double	getGeometricMean() Returns the geometric mean of the values that have been added.
double	getMax() Returns the maximum of the values that have been added.
StorelessUnivariateStatistic	getMaxImpl() Returns the currently configured maximum implementation
double	getMean() Returns the mean of the values that have been added.
StorelessUnivariateStatistic	getMeanImpl() Returns the currently configured mean implementation
double	getMin() Returns the minimum of the values that have been added.
StorelessUnivariateStatistic	getMinImpl() Returns the currently configured minimum implementation
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 values that have been added.
double	getSum() Returns the sum of the values that have been added
StorelessUnivariateStatistic	getSumImpl() Returns the currently configured Sum implementation
StorelessUnivariateStatistic	getSumLogImpl() Returns the currently configured sum of logs implementation
StatisticalSummary	getSummary() Return a StatisticalSummaryValues instance reporting current statistics.
double	getSumOfLogs() Returns the sum of the logs of the values that have been added.
double	getSumsq() Returns the sum of the squares of the values that have been added.
StorelessUnivariateStatistic	getSumsqImpl() Returns the currently configured sum of squares implementation
double	getVariance() Returns the variance of the values that have been added.
StorelessUnivariateStatistic	getVarianceImpl() Returns the currently configured variance implementation
int	hashCode() Returns hash code based on values of statistics
void	setGeoMeanImpl(StorelessUnivariateStatistic geoMeanImpl) Sets the implementation for the geometric mean.
void	setMaxImpl(StorelessUnivariateStatistic maxImpl) Sets the implementation for the maximum.
void	setMeanImpl(StorelessUnivariateStatistic meanImpl) Sets the implementation for the mean.
void	setMinImpl(StorelessUnivariateStatistic minImpl) Sets the implementation for the minimum.
void	setSumImpl(StorelessUnivariateStatistic sumImpl) Sets the implementation for the Sum.
void	setSumLogImpl(StorelessUnivariateStatistic sumLogImpl) Sets the implementation for the sum of logs.
void	setSumsqImpl(StorelessUnivariateStatistic sumsqImpl) Sets the implementation for the sum of squares.
void	setVarianceImpl(StorelessUnivariateStatistic varianceImpl) Sets the implementation for the variance.
String	toString() Generates a text report displaying summary statistics from values that have been added.

Methods inherited from class java.lang.Object

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

Field Detail

n

protected long n

count of values that have been added

secondMoment

protected SecondMoment secondMoment

SecondMoment is used to compute the mean and variance

sum

protected Sum sum

sum of values that have been added

sumsq

protected SumOfSquares sumsq

sum of the square of each value that has been added

min

protected Min min

min of values that have been added

max

protected Max max

max of values that have been added

sumLog

protected SumOfLogs sumLog

sumLog of values that have been added

geoMean

protected GeometricMean geoMean

geoMean of values that have been added

mean

protected Mean mean

mean of values that have been added

variance

protected Variance variance

variance of values that have been added

Constructor Detail

SummaryStatistics

public SummaryStatistics()

Construct a SummaryStatistics instance

SummaryStatistics

public SummaryStatistics(SummaryStatistics original)

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

Parameters:

original - the SummaryStatistics instance to copy

Method Detail

getSummary

public StatisticalSummary getSummary()

Return a StatisticalSummaryValues instance reporting current statistics.

Returns:

Current values of statistics

addValue

public void addValue(double value)

Add a value to the data

Parameters:

value - the value to add

getN

public long getN()

Returns the number of available values

Specified by:

getN in interface StatisticalSummary

Returns:

The number of available values

getSum

public double getSum()

Returns the sum of the values that have been added

Specified by:

getSum in interface StatisticalSummary

Returns:

The sum or Double.NaN if no values have been added

getSumsq

public double getSumsq()

Returns the sum of the squares of the values that have been added.

Double.NaN is returned if no values have been added.

Returns:

The sum of squares

getMean

public double getMean()

Returns the mean of the values that have been added.

Double.NaN is returned if no values have been added.

Specified by:

getMean in interface StatisticalSummary

Returns:

the mean

getStandardDeviation

public double getStandardDeviation()

Returns the standard deviation of the values that have been added.

Double.NaN is returned if no values have been added.

Specified by:

getStandardDeviation in interface StatisticalSummary

Returns:

the standard deviation

getVariance

public double getVariance()

Returns the variance of the values that have been added.

Double.NaN is returned if no values have been added.

Specified by:

getVariance in interface StatisticalSummary

Returns:

the variance

getMax

public double getMax()

Returns the maximum of the values that have been added.

Double.NaN is returned if no values have been added.

Specified by:

getMax in interface StatisticalSummary

Returns:

the maximum

getMin

public double getMin()

Returns the minimum of the values that have been added.

Double.NaN is returned if no values have been added.

Specified by:

getMin in interface StatisticalSummary

Returns:

the minimum

getGeometricMean

public double getGeometricMean()

Returns the geometric mean of the values that have been added.

Double.NaN is returned if no values have been added.

Returns:

the geometric mean

getSumOfLogs

public double getSumOfLogs()

Returns the sum of the logs of the values that have been added.

Double.NaN is returned if no values have been added.

Returns:

the sum of logs

Since:

1.2

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 values that have been added.

Returns Double.NaN if no data values have been added and returns 0 if there is just one value in the data set.

Returns:

second central moment statistic

Since:

2.0

toString

public String toString()

Generates a text report displaying summary statistics from values that have been added.

Overrides:

toString in class Object

Returns:

String with line feeds displaying statistics

Since:

1.2

clear

public void clear()

Resets all statistics and storage

equals

public boolean equals(Object object)

Returns true iff object is a SummaryStatistics instance and all statistics have the same values as this.

Overrides:

equals in class Object

Parameters:

object - the object to test equality against.

Returns:

true if object equals this

hashCode

public int hashCode()

Returns hash code based on values of statistics

Overrides:

hashCode in class Object

Returns:

hash code

getSumImpl

public StorelessUnivariateStatistic getSumImpl()

Returns the currently configured Sum implementation

Returns:

the StorelessUnivariateStatistic implementing the sum

Since:

1.2

setSumImpl

public void setSumImpl(StorelessUnivariateStatistic sumImpl)

Sets the implementation for the Sum.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

sumImpl - the StorelessUnivariateStatistic instance to use for computing the Sum

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getSumsqImpl

public StorelessUnivariateStatistic getSumsqImpl()

Returns the currently configured sum of squares implementation

Returns:

the StorelessUnivariateStatistic implementing the sum of squares

Since:

1.2

setSumsqImpl

public void setSumsqImpl(StorelessUnivariateStatistic sumsqImpl)

Sets the implementation for the sum of squares.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

sumsqImpl - the StorelessUnivariateStatistic instance to use for computing the sum of squares

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getMinImpl

public StorelessUnivariateStatistic getMinImpl()

Returns the currently configured minimum implementation

Returns:

the StorelessUnivariateStatistic implementing the minimum

Since:

1.2

setMinImpl

public void setMinImpl(StorelessUnivariateStatistic minImpl)

Sets the implementation for the minimum.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

minImpl - the StorelessUnivariateStatistic instance to use for computing the minimum

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getMaxImpl

public StorelessUnivariateStatistic getMaxImpl()

Returns the currently configured maximum implementation

Returns:

the StorelessUnivariateStatistic implementing the maximum

Since:

1.2

setMaxImpl

public void setMaxImpl(StorelessUnivariateStatistic maxImpl)

Sets the implementation for the maximum.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

maxImpl - the StorelessUnivariateStatistic instance to use for computing the maximum

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getSumLogImpl

public StorelessUnivariateStatistic getSumLogImpl()

Returns the currently configured sum of logs implementation

Returns:

the StorelessUnivariateStatistic implementing the log sum

Since:

1.2

setSumLogImpl

public void setSumLogImpl(StorelessUnivariateStatistic sumLogImpl)

Sets the implementation for the sum of logs.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

sumLogImpl - the StorelessUnivariateStatistic instance to use for computing the log sum

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getGeoMeanImpl

public StorelessUnivariateStatistic getGeoMeanImpl()

Returns the currently configured geometric mean implementation

Returns:

the StorelessUnivariateStatistic implementing the geometric mean

Since:

1.2

setGeoMeanImpl

public void setGeoMeanImpl(StorelessUnivariateStatistic geoMeanImpl)

Sets the implementation for the geometric mean.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

geoMeanImpl - the StorelessUnivariateStatistic instance to use for computing the geometric mean

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getMeanImpl

public StorelessUnivariateStatistic getMeanImpl()

Returns the currently configured mean implementation

Returns:

the StorelessUnivariateStatistic implementing the mean

Since:

1.2

setMeanImpl

public void setMeanImpl(StorelessUnivariateStatistic meanImpl)

Sets the implementation for the mean.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

meanImpl - the StorelessUnivariateStatistic instance to use for computing the mean

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

getVarianceImpl

public StorelessUnivariateStatistic getVarianceImpl()

Returns the currently configured variance implementation

Returns:

the StorelessUnivariateStatistic implementing the variance

Since:

1.2

setVarianceImpl

public void setVarianceImpl(StorelessUnivariateStatistic varianceImpl)

Sets the implementation for the variance.

This method must be activated before any data has been added - i.e., before addValue has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

varianceImpl - the StorelessUnivariateStatistic instance to use for computing the variance

Throws:

IllegalStateException - if data has already been added (i.e if n > 0)

Since:

1.2

copy

public SummaryStatistics copy()

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

Returns:

a copy of this

copy

public static void copy(SummaryStatistics source,
                        SummaryStatistics dest)

Copies source to dest.

Neither source nor dest can be null.

Parameters:

source - SummaryStatistics to copy

dest - SummaryStatistics to copy to

Throws:

NullPointerException - if either source or dest is null