me.lemire.integercompression
Class NewPFD

java.lang.Object
  me.lemire.integercompression.NewPFD

All Implemented Interfaces:

IntegerCODEC

public final class NewPFD
extends Object
implements IntegerCODEC

NewPFD/NewPFOR

Follows:

H. Yan, S. Ding, T. Suel, Inverted index compression and query processing with optimized document ordering, in: WWW �09, 2009, pp. 401�410.

using Simple16 as the secondary coder. Note that this does not use differential coding: if you are working on sorted lists, you must compute the deltas separately. (Yes, this is true even though the "D" at the end of the name probably stands for delta.) For multi-threaded applications, each thread should use its own NewPFD object.

Author:

Daniel Lemire

Field Summary

protected static int[]	bits
protected static int[]	invbits

Constructor Summary

NewPFD()
Constructor for the NewPFD CODEC.

Method Summary

void	compress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos) Compress data from an array to another array.
protected static void	getBestBFromData(int[] in, int pos, IntWrapper bestb, IntWrapper bestexcept)
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

Field Detail

bits

protected static final int[] bits

invbits

protected static final int[] invbits

Constructor Detail

NewPFD

public NewPFD()

Constructor for the NewPFD CODEC.

Method Detail

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 - location in the input array

inlength - how many integers to compress

out - output array

outpos - where to write in the output array

getBestBFromData

protected static void getBestBFromData(int[] in,
                                       int pos,
                                       IntWrapper bestb,
                                       IntWrapper bestexcept)

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 write the compressed output in out

toString

public String toString()

Overrides:

toString in class Object