ivory.ffg.data

Class DocumentVectorMiniInvertedIndex

java.lang.Object

ivory.ffg.data.DocumentVectorMiniInvertedIndex

All Implemented Interfaces:

DocumentVector, Writable

public class DocumentVectorMiniInvertedIndex
extends Object
implements DocumentVector

Implementation of an (mini-)indexed document vector refered to as IDV. In this class, term ids are encoded using PForDelta whereas positions are compressed using the gamma coding.

Author:

Nima Asadi

Method Summary

Methods

Modifier and Type	Method and Description
int[]	decompressDocument() Decompresses the document vector into a flat array representation
int[][]	decompressPositions(int[] terms) Decompresses/constructs positions.
boolean	equals(Object o)
int	getDocumentLength()
static DocumentVectorMiniInvertedIndex	newInstance(int[] data, List<TermPositions> positions, int documentLength) Constructs an indexed document vector given the input term id vector and the term positions
void	readFields(DataInput input)
static DocumentVectorMiniInvertedIndex	readInstance(DataInput input) Reads and returns an instance of this class from input.
int[]	transformTerms(int[] terms) Transforms query terms
void	write(DataOutput output)

Methods inherited from class java.lang.Object

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

Method Detail

decompressDocument

public int[] decompressDocument()
                         throws IOException

Description copied from interface: DocumentVector

Decompresses the document vector into a flat array representation

Specified by:

decompressDocument in interface DocumentVector

Returns:

Decompressed flat array representation of the document vector

Throws:

IOException

decompressPositions

public int[][] decompressPositions(int[] terms)
                            throws IOException

Description copied from interface: DocumentVector

Decompresses/constructs positions. This method applies the necessary transformation functions tot he input query terms.

Specified by:

decompressPositions in interface DocumentVector

Parameters:

terms - Query terms

Returns:

Position arrays for every term in the query

Throws:

IOException

equals

public boolean equals(Object o)

Overrides:

equals in class Object

getDocumentLength

public int getDocumentLength()

Specified by:

getDocumentLength in interface DocumentVector

Returns:

Length of this document

newInstance

public static DocumentVectorMiniInvertedIndex newInstance(int[] data,
                                          List<TermPositions> positions,
                                          int documentLength)
                                                   throws IOException

Constructs an indexed document vector given the input term id vector and the term positions

Parameters:

data - Array of term ids

positions - List of TermPosition objects, one for each term id

Returns:

A compressed, indexed document vector.

Throws:

IOException

readFields

public void readFields(DataInput input)
                throws IOException

Specified by:

readFields in interface Writable

Throws:

IOException

readInstance

public static DocumentVectorMiniInvertedIndex readInstance(DataInput input)
                                                    throws IOException

Reads and returns an instance of this class from input.

Parameters:

input - DataInput

Returns:

An instance of this class.

Throws:

IOException

transformTerms

public int[] transformTerms(int[] terms)

Description copied from interface: DocumentVector

Transforms query terms

Specified by:

transformTerms in interface DocumentVector

Parameters:

terms - Query terms

Returns:

Transformed query terms

write

public void write(DataOutput output)
           throws IOException

Specified by:

write in interface Writable

Throws:

IOException