Package me.lemire.integercompression

Class BinaryPacking

java.lang.Object

me.lemire.integercompression.BinaryPacking

All Implemented Interfaces:

IntegerCODEC, SkippableIntegerCODEC

public final class BinaryPacking
extends Object
implements IntegerCODEC, SkippableIntegerCODEC

Scheme based on a commonly used idea: can be extremely fast. It encodes integers in blocks of 32 integers. For arrays containing an arbitrary number of integers, you should use it in conjunction with another CODEC:

IntegerCODEC ic = 
  new Composition(new BinaryPacking(), new VariableByte()).

Note that this does not use differential coding: if you are working on sorted lists, use IntegratedBinaryPacking instead.

For details, please see

Daniel Lemire and Leonid Boytsov, Decoding billions of integers per second through vectorization Software: Practice & Experience http://onlinelibrary.wiley.com/doi/10.1002/spe.2203/abstract http://arxiv.org/abs/1209.2137

Daniel Lemire, Leonid Boytsov, Nathan Kurz, SIMD Compression and the Intersection of Sorted Integers http://arxiv.org/abs/1401.6399

Author:

Daniel Lemire

Constructor Summary

Constructors

Constructor	Description
BinaryPacking()

Method Summary

Modifier and Type	Method	Description
void	compress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Compress data from an array to another array.
void	headlessCompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Compress data from an array to another array.
void	headlessUncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos, int num)	Uncompress data from an array to another array.
String	toString()
void	uncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Uncompress data from an array to another array.

Methods inherited from class java.lang.Object

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

Constructor Details

BinaryPacking

public BinaryPacking()

Method Details

compress

public void compress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: IntegerCODEC

Compress data from an array to another array. Both inpos and outpos are modified to represent how much data was read and written to. If 12 ints (inlength = 12) are compressed to 3 ints, then inpos will be incremented by 12 while outpos will be incremented by 3. We use IntWrapper to pass the values by reference.

Specified by:

compress in interface IntegerCODEC

Parameters:

in - input array

inpos - where to start reading in the array

inlength - how many integers to compress

out - output array

outpos - where to write in the output array

headlessCompress

public void headlessCompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: SkippableIntegerCODEC

Compress data from an array to another array. Both inpos and outpos are modified to represent how much data was read and written to. If 12 ints (inlength = 12) are compressed to 3 ints, then inpos will be incremented by 12 while outpos will be incremented by 3. We use IntWrapper to pass the values by reference. Implementation note: contrary to IntegerCODEC.compress(int[], me.lemire.integercompression.IntWrapper, int, int[], me.lemire.integercompression.IntWrapper), this may skip writing information about the number of encoded integers.

Specified by:

headlessCompress in interface SkippableIntegerCODEC

Parameters:

in - input array

inpos - where to start reading in the array

inlength - how many integers to compress

out - output array

outpos - where to write in the output array

uncompress

public void uncompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: IntegerCODEC

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Specified by:

uncompress in interface IntegerCODEC

Parameters:

in - array containing data in compressed form

inpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the compressed output

outpos - where to start writing the uncompressed output in out

headlessUncompress

public void headlessUncompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos,
 int num)

Description copied from interface: SkippableIntegerCODEC

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Specified by:

headlessUncompress in interface SkippableIntegerCODEC

Parameters:

in - array containing data in compressed form

inpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the uncompressed output

outpos - where to start writing the uncompressed output in out

num - number of integers we want to decode. May be less than the actual number of compressed integers

toString

public String toString()

Overrides:

toString in class Object