uk.ac.gla.terrier.structures
Class BlockInvertedIndex

java.lang.Object
  uk.ac.gla.terrier.structures.InvertedIndex
      uk.ac.gla.terrier.structures.BlockInvertedIndex

public class BlockInvertedIndex
extends InvertedIndex

This class implements the block field inverted index for performing retrieval.

Version:

$Revision: 1.27 $

Author:

Douglas Johnson

Field Summary

Fields inherited from class uk.ac.gla.terrier.structures.InvertedIndex

FIELD_LOAD_FACTOR, NORMAL_LOAD_FACTOR

Constructor Summary

BlockInvertedIndex(Lexicon lexicon)
Creates an instance of the BlockInvertedIndex class using the given lexicon.

BlockInvertedIndex(Lexicon lexicon, java.lang.String filename)
Creates an instance of the BlockInvertedIndex class using the given lexicon.

BlockInvertedIndex(Lexicon lexicon, java.lang.String path, java.lang.String prefix)

Method Summary

int[][]	getDocuments(long startOffset, byte startBitOffset, long endOffset, byte endBitOffset) Returns a 2D array containing the document ids, the term frequencies, the field scores the block frequencies and the block ids for the given documents.
int[][]	getDocumentsWithoutBlocks(int termid)
int[][]	getDocumentsWithoutBlocks(int termid, int startDocid, int endDocid)
void	print() Prints out the block inverted index file.

Methods inherited from class uk.ac.gla.terrier.structures.InvertedIndex

close, getBitFile, getDocuments, getDocuments, getDocuments

Methods inherited from class java.lang.Object

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

Constructor Detail

BlockInvertedIndex

public BlockInvertedIndex(Lexicon lexicon)

Creates an instance of the BlockInvertedIndex class using the given lexicon.

Parameters:

lexicon - The lexicon used for retrieval

BlockInvertedIndex

public BlockInvertedIndex(Lexicon lexicon,
                          java.lang.String path,
                          java.lang.String prefix)

BlockInvertedIndex

public BlockInvertedIndex(Lexicon lexicon,
                          java.lang.String filename)

Creates an instance of the BlockInvertedIndex class using the given lexicon.

Parameters:

lexicon - The lexicon used for retrieval

filename - the name of the inverted file

Method Detail

print

public void print()

Prints out the block inverted index file.

Overrides:

print in class InvertedIndex

getDocuments

public int[][] getDocuments(long startOffset,
                            byte startBitOffset,
                            long endOffset,
                            byte endBitOffset)

Returns a 2D array containing the document ids, the term frequencies, the field scores the block frequencies and the block ids for the given documents.

Overrides:

getDocuments in class InvertedIndex

Parameters:

startOffset - start byte of the postings in the inverted file

startBitOffset - start bit of the postings in the inverted file

endOffset - end byte of the postings in the inverted file

endBitOffset - end bit of the postings in the inverted file

Returns:

int[][] the five dimensional [5][] array containing the document ids, frequencies, field scores and block frequencies, while the last vector contains the block identifiers and it has a different length from the document identifiers.

getDocumentsWithoutBlocks

public int[][] getDocumentsWithoutBlocks(int termid,
                                         int startDocid,
                                         int endDocid)

getDocumentsWithoutBlocks

public int[][] getDocumentsWithoutBlocks(int termid)