Core :: Utilities 12.0.6 · org.eclipse.jetty.util.statistic.SampleStatistic

Statistics on a sampled value.

Provides max, total, mean, count, variance, and standard deviation of continuous sequence of samples.

Calculates estimates of mean, variance, and standard deviation characteristics of a sample using a non synchronized approximation of the on-line algorithm presented in Donald Knuth's Art of Computer Programming, Volume 2, Semi numerical Algorithms, 3rd edition, page 232, Boston: Addison-Wesley. That cites a 1962 paper by B.P. Welford: Note on a Method for Calculating Corrected Sums of Squares and Products

This algorithm is also described in Wikipedia in the section "Online algorithm": Algorithms for calculating variance.

Modifier and Type	Field and Description
private final AtomicLong	_count
private final LongAccumulator	_max
private final AtomicLong	_total
private final LongAdder	_totalVariance100

Constructor Summary

Access	Constructor and Description
public	SampleStatistic()

Method Summary

Modifier and Type	Method and Description
public long	Returns: the number of samples recorded getCount() Get the number of samples recorded.
public long	Returns: the max value of the recorded samples getMax() Get the max value of the recorded samples.
public double	Returns: the average value of the samples recorded, or zero if there are no samples getMean() Get the average value of the samples recorded, or zero if there are no samples.
public double	Returns: the standard deviation of the samples recorded getStdDev() Get the standard deviation of the samples recorded.
public long	Returns: the sum of all the recorded samples getTotal() Get the sum of all the recorded samples.
public double	Returns: the variance of the samples recorded, or zero if there are less than 2 samples getVariance() Get the variance of the samples recorded, or zero if there are less than 2 samples.
public void	record(long the value to record. sample) Records a sample value.
public void	reset() Resets the statistics.
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll wait wait wait

Field Detail

_count	back to summary
private final AtomicLong _count

_max	back to summary
private final LongAccumulator _max

_total	back to summary
private final AtomicLong _total

_totalVariance100	back to summary
private final LongAdder _totalVariance100

Constructor Detail

SampleStatistic	back to summary
public SampleStatistic()

Method Detail

getCount	back to summary
public long getCount() Get the number of samples recorded. Returns:long the number of samples recorded

getCount

back to summary

public long getCount()

Get the number of samples recorded.

Returns:long: the number of samples recorded

getMax	back to summary
public long getMax() Get the max value of the recorded samples. Returns:long the max value of the recorded samples

getMax

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public long getMax()

Get the max value of the recorded samples.

Returns:long: the max value of the recorded samples

getMean	back to summary
public double getMean() Get the average value of the samples recorded, or zero if there are no samples. Returns:double the average value of the samples recorded, or zero if there are no samples

getMean

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public double getMean()

Get the average value of the samples recorded, or zero if there are no samples.

Returns:double: the average value of the samples recorded, or zero if there are no samples

getStdDev	back to summary
public double getStdDev() Get the standard deviation of the samples recorded. Returns:double the standard deviation of the samples recorded

getStdDev

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public double getStdDev()

Get the standard deviation of the samples recorded.

Returns:double: the standard deviation of the samples recorded

getTotal	back to summary
public long getTotal() Get the sum of all the recorded samples. Returns:long the sum of all the recorded samples

getTotal

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public long getTotal()

Get the sum of all the recorded samples.

Returns:long: the sum of all the recorded samples

getVariance	back to summary
public double getVariance() Get the variance of the samples recorded, or zero if there are less than 2 samples. Returns:double the variance of the samples recorded, or zero if there are less than 2 samples

getVariance

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public double getVariance()

Get the variance of the samples recorded, or zero if there are less than 2 samples.

Returns:double: the variance of the samples recorded, or zero if there are less than 2 samples

record	back to summary
public void record(long sample) Records a sample value. Parameters sample:long the value to record.

record

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public void record(long sample)

Records a sample value.

Parameters

sample:long: the value to record.

reset	back to summary
public void reset() Resets the statistics.

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Returns:String a string representation of the object. Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object.

Returns:String

a string representation of the object.

Annotations