org.apache.cassandra.utils

Class StreamingHistogram

java.lang.Object

org.apache.cassandra.utils.StreamingHistogram

public class StreamingHistogram
extends java.lang.Object

Histogram that can be constructed from streaming of data. The algorithm is taken from following paper: Yael Ben-Haim and Elad Tom-Tov, "A Streaming Parallel Decision Tree Algorithm" (2010) http://jmlr.csail.mit.edu/papers/volume11/ben-haim10a/ben-haim10a.pdf

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StreamingHistogram.StreamingHistogramSerializer

Field Summary

Fields

Modifier and Type	Field and Description
static StreamingHistogram.StreamingHistogramSerializer	serializer

Constructor Summary

Constructors

Constructor and Description
StreamingHistogram(int maxBinSize, int maxSpoolSize, int roundSeconds) Creates a new histogram with max bin size of maxBinSize

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o)
void	flushHistogram() Drain the temporary spool into the final bins
java.util.Map<java.lang.Number,long[]>	getAsMap()
int	hashCode()
void	merge(StreamingHistogram other) Merges given histogram with this histogram.
double	sum(double b) Calculates estimated number of points in interval [-inf,b].
void	update(java.lang.Number p) Adds new point p to this histogram.
void	update(java.lang.Number p, long m) Adds new point p with value m to this histogram.

Methods inherited from class java.lang.Object

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

Field Detail

serializer

public static final StreamingHistogram.StreamingHistogramSerializer serializer

Constructor Detail

StreamingHistogram

public StreamingHistogram(int maxBinSize,
                          int maxSpoolSize,
                          int roundSeconds)

Creates a new histogram with max bin size of maxBinSize

Parameters:

maxBinSize - maximum number of bins this histogram can have

Method Detail

update

public void update(java.lang.Number p)

Adds new point p to this histogram.

Parameters:

p -

update

public void update(java.lang.Number p,
                   long m)

Adds new point p with value m to this histogram.

Parameters:

p -

m -

flushHistogram

public void flushHistogram()

Drain the temporary spool into the final bins

merge

public void merge(StreamingHistogram other)

Merges given histogram with this histogram.

Parameters:

other - histogram to merge

sum

public double sum(double b)

Calculates estimated number of points in interval [-inf,b].

Parameters:

b - upper bound of a interval to calculate sum

Returns:

estimated number of points in a interval [-inf,b].

getAsMap

public java.util.Map<java.lang.Number,long[]> getAsMap()

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object