org.apache.lucene.search.similar
Class SimilarityQueries

java.lang.Object
  org.apache.lucene.search.similar.SimilarityQueries

public final class SimilarityQueries
extends Object

Simple similarity measures.

See Also:

MoreLikeThis

Method Summary

static Query

formSimilarQuery(String body, Analyzer a, String field, Set<?> stop) Simple similarity query generators.

Methods inherited from class java.lang.Object

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

Method Detail

formSimilarQuery

public static Query formSimilarQuery(String body,
                                     Analyzer a,
                                     String field,
                                     Set<?> stop)
                              throws IOException

Simple similarity query generators. Takes every unique word and forms a boolean query where all words are optional. After you get this you'll use to to query your IndexSearcher for similar docs. The only caveat is the first hit returned should be your source document - you'll need to then ignore that.

So, if you have a code fragment like this:
Query q = formSimilaryQuery( "I use Lucene to search fast. Fast searchers are good", new StandardAnalyzer(), "contents", null);

The query returned, in string form, will be '(i use lucene to search fast searchers are good').

The philosophy behind this method is "two documents are similar if they share lots of words". Note that behind the scenes, Lucene's scoring algorithm will tend to give two documents a higher similarity score if the share more uncommon words.

This method is fail-safe in that if a long 'body' is passed in and BooleanQuery.add() (used internally) throws BooleanQuery.TooManyClauses, the query as it is will be returned.

Parameters:

body - the body of the document you want to find similar documents to

a - the analyzer to use to parse the body

field - the field you want to search on, probably something like "contents" or "body"

stop - optional set of stop words to ignore

Returns:

a query with all unique words in 'body'

Throws:

IOException - this can't happen...