uk.ac.gla.terrier.structures.indexing.singlepass
Class Inverted2DirectIndexBuilder

java.lang.Object
  uk.ac.gla.terrier.structures.indexing.singlepass.Inverted2DirectIndexBuilder

Direct Known Subclasses:

BlockInverted2DirectIndexBuilder

public class Inverted2DirectIndexBuilder
extends java.lang.Object

Create a direct index from an InvertedIndex. The algorithm is similar to that followed by InvertedIndexBuilder. To summarise, InvertedIndexBuilder builds an InvertedIndex from a DirectIndex. This class does the opposite, building a DirectIndex from an InvertedIndex.

Algorithm:
For a selection of document ids (Scan the inverted index looking for postings with these document ids) For each term in the inverted index Select required postings from all the postings of that term Add these to posting objects that represents each document &nsbp;For each posting object Write out the postings for that document

Notes:
This algorithm assumes that termids start at 0 and are strictly increasing. This assumption holds true only for inverted indices generated by the single pass indexing method.

Properties:

1. inverted2direct.processtokens - total number of tokens to attempt each iteration. Defaults to 100000000. Memory usage would more likely be linked to the number of pointers, however as the document index does not contain the number of unique terms in each document, the pointers calculation is impossible to make.

Since:

2.0

Version:

$Revision: 1.8 $

Author:

Craig Macdonald

Constructor Summary

Inverted2DirectIndexBuilder(Index i)
Construct a new instance of this builder class

Method Summary

void	createDirectIndex() create the direct index when the collection contains an existing inverted index
static void	main(java.lang.String[] args)

Methods inherited from class java.lang.Object

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

Constructor Detail

Inverted2DirectIndexBuilder

public Inverted2DirectIndexBuilder(Index i)

Construct a new instance of this builder class

Method Detail

createDirectIndex

public void createDirectIndex()

create the direct index when the collection contains an existing inverted index

main

public static void main(java.lang.String[] args)