Package org.terrier.structures.postings

Provides classes representing single postings and atreams of postings in a posting list (e.g.

See:
          Description

Interface Summary
BitWritablePosting As WritablePosting, but using the BitWritable interface.
BlockPosting Interface implemented by Posting objects that have position information recorded.
FieldPosting Interface implemented by Posting objects that have field information recorded.
IterablePosting An interface that allows a list of postings to be iterated over
Posting This interface represents one posting in a posting list.
WritablePosting Allow a Posting to be written to a DataOut
 

Class Summary
ArrayOfBasicIterablePosting An instance of IterablePostings that works with passed arrays of ids and frequencies
ArrayOfIdsIterablePosting An instance of IterablePostings that works with a passed array of ids
BasicIterablePosting Basic inverted and direct index format: [gamma(first docid +1) unary (frequency)], [gamma(delta docid) unary(frequency)]
BasicIterablePostingDocidOnly Posting iterator class that only returns identifiers, not frequencies.
BasicPostingImpl Implementation of a Posting that is non-iterable.
BlockFieldIterablePosting class BlockFieldIterablePosting
BlockFieldORIterablePosting ORIterablePosting implementation that implements FieldPosting and BlockPosting
BlockFieldPostingImpl A writable block field posting list
BlockIterablePosting A writable block iterable posting list
BlockORIterablePosting ORIterablePosting implementation that implements BlockPosting
BlockPostingImpl BlockPostingImpl class
FieldIterablePosting A posting iterator for field postings.
FieldORIterablePosting ORIterablePosting implementation that implements FieldPosting
FieldPostingImpl Implementation of a posting containing fields
IterablePostingImpl A base implementation of an IterablePosting, that provides a base implementation of next(int) method.
ORIterablePosting An IterablePosting that combines more than one IterablePosting into a single IterablePosting.
PostingIdComparator A comparator object for Posting objects, where they are sorted by id.
PostingUtil Handy methods for Posting classes, such as obtaining all ids in a posting list, or selecting the minimum id in an array of posting lists.
 

Package org.terrier.structures.postings Description

Provides classes representing single postings and atreams of postings in a posting list (e.g. an inverted index or a direct index).

A single posting (e.g. occurrences of a term in document) is represented by a Posting object.

Posting p;
System.out.println("Docid "+ p.getId() + " has " + p.getFrequency() + " occurrences");

A stream of postings (e.g. terms in a document or occurrences of a term) are represented by an IterablePosting stream.

IterablePosting ip = //obtain from InvertedIndex;
while(ip.next() != IterablePosting.EOL)
{
  System.err.println("Docid "+ ip.getId() + " has " + ip.getFrequency() + " occurrences");
}

More complex posting implementations are supported by other Posting child interfaces:

In all cases during retrieval, IterablePosting implementations which also implement Posting, BlockPosting and/or FieldPosting are used, depending on how indexing has been performed. To see how to configure indexing, see Configure Indexing.



Terrier 3.5. Copyright © 2004-2011 University of Glasgow