com.clearspring.analytics.stream.cardinality

Class AdaptiveCounting

java.lang.Object

com.clearspring.analytics.stream.cardinality.LogLog

com.clearspring.analytics.stream.cardinality.AdaptiveCounting

All Implemented Interfaces:

ICardinality

public class AdaptiveCounting
extends LogLog

Based on the adaptive counting approach of:
Fast and Accurate Traffic Matrix Measurement Using Adaptive Cardinality Counting
by: Cai, Pan, Kwok, and Hwang

TODO: use 5 bits/bucket instead of 8 (37.5% size reduction)
TODO: super-LogLog optimizations

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AdaptiveCounting.Builder

Nested classes/interfaces inherited from class com.clearspring.analytics.stream.cardinality.LogLog

LogLog.LogLogMergeException

Field Summary

Fields

Modifier and Type	Field and Description
protected int	b_e Number of empty buckets
protected double	B_s Switching empty bucket ratio

Fields inherited from class com.clearspring.analytics.stream.cardinality.LogLog

Ca, k, m, M, mAlpha, Rsum

Constructor Summary

Constructors

Constructor and Description
AdaptiveCounting(byte[] M)
AdaptiveCounting(int k)

Method Summary

Methods

Modifier and Type	Method and Description
long	cardinality()
ICardinality	merge(ICardinality... estimators) Merges estimators to produce a new estimator for the combined streams of this estimator and those passed as arguments.
static AdaptiveCounting	mergeEstimators(LogLog... estimators) Merges estimators to produce an estimator for their combined streams
boolean	offer(Object o)
protected static byte	rho(long x, int k) Computes the position of the first set bit of the last Long.SIZE-k bits

Methods inherited from class com.clearspring.analytics.stream.cardinality.LogLog

getBytes, offerHashed, offerHashed, rho, sizeof

Methods inherited from class java.lang.Object

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

Field Detail

b_e

protected int b_e

Number of empty buckets

B_s

protected final double B_s

Switching empty bucket ratio

See Also:

Constant Field Values

Constructor Detail

AdaptiveCounting

public AdaptiveCounting(int k)

AdaptiveCounting

public AdaptiveCounting(byte[] M)

Method Detail

offer

public boolean offer(Object o)

Specified by:

offer in interface ICardinality

Overrides:

offer in class LogLog

Parameters:

o - stream element

Returns:

false if the value returned by cardinality() is unaffected by the appearance of o in the stream.

cardinality

public long cardinality()

Specified by:

cardinality in interface ICardinality

Overrides:

cardinality in class LogLog

Returns:

the number of unique elements in the stream or an estimate thereof

rho

protected static byte rho(long x,
       int k)

Computes the position of the first set bit of the last Long.SIZE-k bits

Returns:

Long.SIZE-k if the last k bits are all zero

merge

public ICardinality merge(ICardinality... estimators)
                   throws LogLog.LogLogMergeException

Description copied from interface: ICardinality

Merges estimators to produce a new estimator for the combined streams of this estimator and those passed as arguments.

Nor this estimator nor the one passed as parameters are modified.

Specified by:

merge in interface ICardinality

Overrides:

merge in class LogLog

Parameters:

estimators - Zero or more compatible estimators

Returns:

this if estimators is null or no arguments are passed

Throws:

LogLogMergeException - if estimators are not mergeable (all estimators must be instances of LogLog of the same size)

LogLog.LogLogMergeException

mergeEstimators

public static AdaptiveCounting mergeEstimators(LogLog... estimators)
                                        throws LogLog.LogLogMergeException

Merges estimators to produce an estimator for their combined streams

Parameters:

estimators -

Returns:

merged estimator or null if no estimators were provided

Throws:

LogLogMergeException - if estimators are not mergeable (all estimators must be the same size)

LogLog.LogLogMergeException