com.clearspring.analytics.stream.frequency

Class CountMinSketch

java.lang.Object

com.clearspring.analytics.stream.frequency.CountMinSketch

All Implemented Interfaces:

IFrequency

public class CountMinSketch
extends Object
implements IFrequency

Count-Min Sketch datastructure. An Improved Data Stream Summary: The Count-Min Sketch and its Applications http://www.eecs.harvard.edu/~michaelm/CS222/countmin.pdf

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	CountMinSketch.CMSMergeException

Field Summary

Fields

Modifier and Type	Field and Description
static long	PRIME_MODULUS

Constructor Summary

Constructors

Constructor and Description
CountMinSketch(double epsOfTotalCount, double confidence, int seed)
CountMinSketch(int depth, int width, int seed)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(long item, long count)
void	add(String item, long count)
static CountMinSketch	deserialize(byte[] data)
long	estimateCount(long item) The estimate is correct within 'epsilon' * (total item count), with probability 'confidence'.
long	estimateCount(String item)
double	getConfidence()
double	getRelativeError()
static CountMinSketch	merge(CountMinSketch... estimators) Merges count min sketches to produce a count min sketch for their combined streams
static byte[]	serialize(CountMinSketch sketch)
long	size()

Methods inherited from class java.lang.Object

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

Field Detail

PRIME_MODULUS

public static final long PRIME_MODULUS

See Also:

Constant Field Values

Constructor Detail

CountMinSketch

public CountMinSketch(int depth,
              int width,
              int seed)

CountMinSketch

public CountMinSketch(double epsOfTotalCount,
              double confidence,
              int seed)

Method Detail

getRelativeError

public double getRelativeError()

getConfidence

public double getConfidence()

add

public void add(long item,
       long count)

Specified by:

add in interface IFrequency

add

public void add(String item,
       long count)

Specified by:

add in interface IFrequency

size

public long size()

Specified by:

size in interface IFrequency

estimateCount

public long estimateCount(long item)

The estimate is correct within 'epsilon' * (total item count), with probability 'confidence'.

Specified by:

estimateCount in interface IFrequency

estimateCount

public long estimateCount(String item)

Specified by:

estimateCount in interface IFrequency

merge

public static CountMinSketch merge(CountMinSketch... estimators)
                            throws CountMinSketch.CMSMergeException

Merges count min sketches to produce a count min sketch for their combined streams

Parameters:

estimators -

Returns:

merged estimator or null if no estimators were provided

Throws:

CountMinSketch.CMSMergeException - if estimators are not mergeable (same depth, width and seed)

serialize

public static byte[] serialize(CountMinSketch sketch)

deserialize

public static CountMinSketch deserialize(byte[] data)