uk.ac.starlink.ttools.plot2.layer

Class AdaptiveBinList

java.lang.Object

uk.ac.starlink.ttools.plot2.layer.AdaptiveBinList

All Implemented Interfaces:

BinList

public class AdaptiveBinList
extends Object
implements BinList

BinList implementation that starts off using a hash-based implementation, but switches to an array-based implementation if the hash gets full enough to make it worth while.

Since:

15 Jan 2019

Author:

Mark Taylor

Nested Class Summary

Nested classes/interfaces inherited from interface uk.ac.starlink.ttools.plot2.layer.BinList

BinList.Result

Constructor Summary

Constructors

Constructor and Description
AdaptiveBinList(int size, Combiner combiner, int factThresh) Constructor.

Method Summary

Modifier and Type	Method and Description
BinList	getBaseBinList() Returns the bin list to which this one is currently delegating its operations.
Combiner.Container	getBinContainer(long index) Returns a container representing the current contents of a given bin.
Combiner	getCombiner() Returns the combination method used for bins.
BinList.Result	getResult() Returns an object containing the result values accumulated into the bins so far.
long	getSize() Returns the maximum number of bins.
boolean	isHash() Indicates which underlying BinList implementation is currently in use.
void	submitToBin(long index, double datum) Adds a given numeric value to the bin at the given index.

Methods inherited from class java.lang.Object

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

Constructor Detail

AdaptiveBinList

public AdaptiveBinList(int size,
                       Combiner combiner,
                       int factThresh)

Constructor. The factThresh tuning parameter should be set to a value close to the ratio of HashBinList bin size to ArrayBinList bin size (in terms of storage). Object overhead is typically 2 words (16 bytes), so if the array has one double per bin and the hash has one (Long,Combiner.Container) pair per bin, the ratio will be at least 6.

Parameters:

size - maximum number of bins

combiner - combiner

factThresh - thershold factor - once size/factThresh bins are occupied, an array will be used instead

Method Detail

getCombiner

public Combiner getCombiner()

Description copied from interface: BinList

Returns the combination method used for bins.

Specified by:

getCombiner in interface BinList

Returns:

combiner

getSize

public long getSize()

Description copied from interface: BinList

Returns the maximum number of bins. All bins have an index in the range 0..size-1.

Specified by:

getSize in interface BinList

Returns:

bin count

submitToBin

public void submitToBin(long index,
                        double datum)

Description copied from interface: BinList

Adds a given numeric value to the bin at the given index. In general, NaN values should not be submitted.

Specified by:

submitToBin in interface BinList

Parameters:

index - bin index

datum - finite value to submit to the bin

getBinContainer

public Combiner.Container getBinContainer(long index)

Description copied from interface: BinList

Returns a container representing the current contents of a given bin. This is only intended for reading; the effect of submitting additional data to the returned container is not defined.

This method is here to support conversion between different BinList implementations.

Specified by:

getBinContainer in interface BinList

Parameters:

index - bin index

Returns:

container instance reporting the current state of the bin; may be null if the bin is not populated

getResult

public BinList.Result getResult()

Description copied from interface: BinList

Returns an object containing the result values accumulated into the bins so far.

It is up to implementations to decide how to implement this method. In some cases the return value may be an adapter that extracts results as required from the data structure used for value accumulation, but in others it may return a new data structure which copies the accumulated values to a more compact form up front. Therefore this may or may not be an expensive method, and the return value may or may not be affected by subsequent BinList.submitToBin(long, double) calls.

Specified by:

getResult in interface BinList

Returns:

accumulated bin values

getBaseBinList

public BinList getBaseBinList()

Returns the bin list to which this one is currently delegating its operations.

Returns:

base bin list

isHash

public boolean isHash()

Indicates which underlying BinList implementation is currently in use. It starts off true at object construction time, but may turn false if enough data are submitted. It will never change back again.

Returns:

true if underlying bin list is hash-based, false if it's array-based