com.yahoo.sketches.quantiles

Class DoublesSketchBuilder

java.lang.Object

com.yahoo.sketches.quantiles.DoublesSketchBuilder

public class DoublesSketchBuilder
extends Object

For building a new quantiles DoublesSketch.

Author:

Lee Rhodes

Constructor Summary

Constructors

Constructor and Description
DoublesSketchBuilder() Constructor for a new DoublesSketchBuilder.

Method Summary

Modifier and Type	Method and Description
UpdateDoublesSketch	build() Returns an UpdateDoublesSketch with the current configuration of this Builder.
UpdateDoublesSketch	build(int k) Returns a quantiles UpdateDoublesSketch with the current configuration of this builder and the given parameter k.
int	getK() Gets the current configured value of k
Memory	getMemory() Gets the configured Memory to be initialized by the sketch for off-heap use.
DoublesSketchBuilder	initMemory(Memory mem) Specifies the Memory to be initialized for a new off-heap version of the sketch.
DoublesSketchBuilder	setK(int k) Sets the parameter k that determines the accuracy and size of the sketch.
String	toString() Creates a human readable string that describes the current configuration of this builder.

Methods inherited from class java.lang.Object

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

Constructor Detail

DoublesSketchBuilder

public DoublesSketchBuilder()

Constructor for a new DoublesSketchBuilder. The default configuration is

• k: 128. This produces a normalized rank error of about 1.7%
• Memory: null

Method Detail

setK

public DoublesSketchBuilder setK(int k)

Sets the parameter k that determines the accuracy and size of the sketch.

Parameters:

k - determines the accuracy and size of the sketch. It is recommended that k be a power of 2 to enable unioning of sketches with different values of k. It is only possible to union from larger values of k to smaller values.

Returns:

this builder

initMemory

public DoublesSketchBuilder initMemory(Memory mem)

Specifies the Memory to be initialized for a new off-heap version of the sketch.

Parameters:

mem - the given Memory.

Returns:

this builder

getK

public int getK()

Gets the current configured value of k

Returns:

the current configured value of k

getMemory

public Memory getMemory()

Gets the configured Memory to be initialized by the sketch for off-heap use.

Returns:

the configured Memory.

build

public UpdateDoublesSketch build()

Returns an UpdateDoublesSketch with the current configuration of this Builder.

Returns:

a UpdateDoublesSketch

build

public UpdateDoublesSketch build(int k)

Returns a quantiles UpdateDoublesSketch with the current configuration of this builder and the given parameter k.

Parameters:

k - determines the accuracy and size of the sketch. k must be greater than 1 and less than 65536. It is recommended that k be a power of 2 to enable merging of sketches with different values of k. However, in this case it is only possible to merge from larger values of k to smaller values.

Returns:

an UpdateDoublesSketch

toString

public String toString()

Creates a human readable string that describes the current configuration of this builder.

Overrides:

toString in class Object