org.terrier.structures
Class DirectIndex

java.lang.Object
  org.terrier.structures.BitPostingIndex
      org.terrier.structures.DirectIndex

All Implemented Interfaces:

Closeable, PostingIndex<BitIndexPointer>

Direct Known Subclasses:

BlockDirectIndex

public class DirectIndex
extends BitPostingIndex

A class that implements the direct index and saves information about whether a term appears in one of the specified fields.

Author:

Douglas Johnson, Vassilis Plachouras, Craig Macdonald

Field Summary

protected DocumentIndex	docIndex The document index employed for retrieving the document offsets.
protected static org.apache.log4j.Logger	logger The logger used for the Lexicon

Fields inherited from class org.terrier.structures.BitPostingIndex

fieldCount, file, index, postingConstructor, postingImplementation

Constructor Summary

DirectIndex(Index index, String structureName)
Constructs an instance of the class with the given index, using the specified structure name.

DirectIndex(Index index, String structureName, Class<? extends IterablePosting> postingClass)
Constructs an instance of the class with

Method Summary

int[][]	getTerms(BitIndexPointer pointer) Get the terms for the document at the specified bit index pointer.
int[][]	getTerms(int docid) Returns a two dimensional array containing the term ids and the term frequencies for the given document.
static void	main(String[] args) main

Methods inherited from class org.terrier.structures.BitPostingIndex

close, getPostings, setPostingImplementation

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final org.apache.log4j.Logger logger

The logger used for the Lexicon

docIndex

protected DocumentIndex docIndex

The document index employed for retrieving the document offsets.

Constructor Detail

DirectIndex

public DirectIndex(Index index,
                   String structureName)
            throws IOException

Constructs an instance of the class with the given index, using the specified structure name.

Parameters:

index - The index to be used

structureName - the name of this direct index

Throws:

IOException

DirectIndex

public DirectIndex(Index index,
                   String structureName,
                   Class<? extends IterablePosting> postingClass)
            throws IOException

Constructs an instance of the class with

Parameters:

index -

structureName -

postingClass -

Throws:

IOException

Method Detail

getTerms

public int[][] getTerms(int docid)
                 throws IOException

Returns a two dimensional array containing the term ids and the term frequencies for the given document.

Parameters:

docid - the document identifier of the document which terms we retrieve.

Returns:

int[][] the two dimensional [n][3] array containing the term ids, frequencies and field scores. If the given document identifier is not found in the document index, then the method returns null. If fields are not used, then the dimension of the returned array are [n][2].

Throws:

IOException

getTerms

public int[][] getTerms(BitIndexPointer pointer)
                 throws IOException

Get the terms for the document at the specified bit index pointer. See getTerms(int docid) for the return specification.

Throws:

IOException

main

public static void main(String[] args)
                 throws Exception

main

Parameters:

args -

Throws:

Exception