com.yahoo.sketches.tuple

Class ArrayOfDoublesSketch

java.lang.Object

com.yahoo.sketches.tuple.ArrayOfDoublesSketch

Direct Known Subclasses:

ArrayOfDoublesCompactSketch, ArrayOfDoublesUpdatableSketch

public abstract class ArrayOfDoublesSketch
extends Object

The base class for the tuple sketch of type ArrayOfDoubles, where an array of double values is associated with each key. A primitive array of doubles is used here, as opposed to a generic Summary object, for improved performance.

Method Summary

Modifier and Type	Method and Description
double	getEstimate() Estimates the cardinality of the set (number of unique values presented to the sketch)
double	getLowerBound(int numStdDev) Gets the approximate lower error bound given the specified number of Standard Deviations.
int	getNumValues()
abstract int	getRetainedEntries()
double	getTheta() Gets the value of theta as a double between zero and one
double	getUpperBound(int numStdDev) Gets the approximate upper error bound given the specified number of Standard Deviations.
abstract double[][]	getValues()
boolean	isEmpty() See Empty
boolean	isEstimationMode() Returns true if the sketch is Estimation Mode (as opposed to Exact Mode).
abstract ArrayOfDoublesSketchIterator	iterator()
abstract byte[]	toByteArray()

Methods inherited from class java.lang.Object

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

Method Detail

getEstimate

public double getEstimate()

Estimates the cardinality of the set (number of unique values presented to the sketch)

Returns:

best estimate of the number of unique values

getUpperBound

public double getUpperBound(int numStdDev)

Gets the approximate upper error bound given the specified number of Standard Deviations. This will return getEstimate() if isEmpty() is true.

Parameters:

numStdDev - See Number of Standard Deviations

Returns:

the upper bound.

getLowerBound

public double getLowerBound(int numStdDev)

Gets the approximate lower error bound given the specified number of Standard Deviations. This will return getEstimate() if isEmpty() is true.

Parameters:

numStdDev - See Number of Standard Deviations

Returns:

the lower bound.

isEmpty

public boolean isEmpty()

See Empty

Returns:

true if empty.

getNumValues

public int getNumValues()

Returns:

number of double values associated with each key

isEstimationMode

public boolean isEstimationMode()

Returns true if the sketch is Estimation Mode (as opposed to Exact Mode). This is true if theta < 1.0 AND isEmpty() is false.

Returns:

true if the sketch is in estimation mode.

getTheta

public double getTheta()

Gets the value of theta as a double between zero and one

Returns:

the value of theta as a double

getRetainedEntries

public abstract int getRetainedEntries()

Returns:

number of retained entries

toByteArray

public abstract byte[] toByteArray()

Returns:

serialized representation of the sketch

getValues

public abstract double[][] getValues()

Returns:

array of arrays of double values in the sketch

iterator

public abstract ArrayOfDoublesSketchIterator iterator()

Returns:

iterator over the sketch