it.unimi.di.big.mg4j.index.cluster

Interface LexicalPartitioningStrategy

All Superinterfaces:

PartitioningStrategy, Serializable

All Known Implementing Classes:

ContiguousLexicalStrategy

public interface LexicalPartitioningStrategy
extends PartitioningStrategy

A way to associate a term number with a local index out of a given set and a local term number in the local index.

When partitioning lexically an index (i.e., termwise), we need a way to associate to each term a local index (the index that will contain the postings of that term) and a local term number (the number of the term in the local index).

Usually, a lexical partitioning strategy has a matching LexicalClusteringStrategy whose methods satisfy the following equations:

 globalNumber(localIndex(t), localNumber(t)) = t
 <localIndex(globalNumber(i, l)), localNumber(globalNumber(i, l))> = <i, l>
 

Author:

Alessandro Arrabito, Sebastiano Vigna

Method Summary

Methods

Modifier and Type	Method and Description
int	localIndex(long globalNumber) Returns the index to which a given term number is mapped by this strategy.
long	localNumber(long globalNumber) Returns the local term number given a global term number.

Methods inherited from interface it.unimi.di.big.mg4j.index.cluster.PartitioningStrategy

numberOfLocalIndices, properties

Method Detail

localIndex

int localIndex(long globalNumber)

Returns the index to which a given term number is mapped by this strategy.

Parameters:

globalNumber - the term global number.

Returns:

the corresponding local index, or -1 if the term should be removed from the partitioned index.

localNumber

long localNumber(long globalNumber)

Returns the local term number given a global term number.

Parameters:

globalNumber - a global term number.

Returns:

the corresponding local term number, or -1 if the term should be removed from the partitioned index.