Module com.carrotsearch.hppc

Package com.carrotsearch.hppc

Class PlaModel

java.lang.Object

com.carrotsearch.hppc.PlaModel

All Implemented Interfaces:

Accountable

public class PlaModel
extends Object
implements Accountable

Optimal Piecewise Linear Approximation Model for KType keys.

Learns a mapping that returns a position for a KType key which is at most epsilon away from the correct one in a sorted list of keys. It is optimal and piecewise because it learns the minimum number of epsilon-approximate segments.

The PLA-model consists of a sequence segments. A segment s is a triple (key,slope,intercept) that indexes a range of keys through the function fs(k) = k × slope + intercept, which provides an epsilon-approximation of the position of the key k.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	PlaModel.SegmentConsumer	Consumer notified when a new segment is built by the PlaModel.

Constructor Summary

Constructors

Constructor	Description
PlaModel(int epsilon)	Creates an optimal PLA-model with the provided epsilon precision.

Method Summary

Modifier and Type	Method	Description
void	addKey(double key, int index, PlaModel.SegmentConsumer segmentConsumer)	Adds a key to this PLA-model.
void	finish(PlaModel.SegmentConsumer segmentConsumer)	Finishes the PLA-model construction.
long	ramBytesAllocated()	Allocated memory estimation
long	ramBytesUsed()	Bytes that is actually been used
void	setEpsilon(int epsilon)	Sets epsilon precision which must be greater than or equal to 0.

Methods inherited from class java.lang.Object

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

Constructor Details

PlaModel

public PlaModel(int epsilon)

Creates an optimal PLA-model with the provided epsilon precision.

Parameters:

epsilon - must be greater than or equal to 0.

Method Details

setEpsilon

public void setEpsilon(int epsilon)

Sets epsilon precision which must be greater than or equal to 0.

addKey

public void addKey(double key,
 int index,
 PlaModel.SegmentConsumer segmentConsumer)

Adds a key to this PLA-model. The keys must be provided in a strictly increasing sequence. That is, the key must be greater than the previous key.

Parameters:

index - The index of the key in the sorted key list.

segmentConsumer - The consumer to call when a new segment is built in the PLA-model.

finish

public void finish(PlaModel.SegmentConsumer segmentConsumer)

Finishes the PLA-model construction. Declares that no additional keys will be added. Builds the last segment and calls the provided PlaModel.SegmentConsumer.

ramBytesAllocated

public long ramBytesAllocated()

Description copied from interface: Accountable

Allocated memory estimation

Specified by:

ramBytesAllocated in interface Accountable

Returns:

Ram allocated in bytes

ramBytesUsed

public long ramBytesUsed()

Description copied from interface: Accountable

Bytes that is actually been used

Specified by:

ramBytesUsed in interface Accountable

Returns:

Ram used in bytes