Hi Otis,
One use case I had for a similar filter for a customer was some ngramming approach. The tokenization before was there to create “normalized” tokens, which were then be glued together (with or w/o whitespace) and ngrammed (means several ngram tokens created from the glued-together thingie). Uwe ----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen <http://www.thetaphi.de/> http://www.thetaphi.de eMail: [email protected] From: Otis Gospodnetic [mailto:[email protected]] Sent: Thursday, November 01, 2012 8:01 PM To: [email protected] Subject: Re: Posting updated ConcatFilter code, using 4.0.0 compatible classes Hi Mark, Out of curiosity, what was your use case? Thanks, Otis -- Search Analytics - http://sematext.com/search-analytics/index.html Performance Monitoring - http://sematext.com/spm/index.html On Wed, Oct 31, 2012 at 10:56 PM, Mark Bennett <[email protected]> wrote: This filter lets you "glue" tokens back together. This has been discussed and posted on the list before, but this updated version uses all the preferred 4.x classes. Normally you wouldn't want to stick tokens back together, but if you've found this post, you probably have some atypical need for it (as I did) As an example you could: * Let tokenizer break up text on white spaces * Then lowercase * then remove stop words * ***then concatenate all the words back together into one string*** You'll need: * ConcatFilter.java (for lucene, below) * ConcatFilterFactory.java (for solr, below) * entry in your schema schema.xml entry ---------- ... <fieldType ...> <analyzer> ... <filter class="solr.ConcatFilterFactory" /> ... </analyzer> </fieldType> ... ConcatFilter.java ----------------- package org.apache.lucene.analysis; import java.io.IOException; import org.apache.lucene.analysis.TokenFilter; import org.apache.lucene.analysis.TokenStream; import org.apache.lucene.analysis.tokenattributes.CharTermAttribute; public class ConcatFilter extends TokenFilter { protected CharTermAttribute charTermAttr; public ConcatFilter(TokenStream input) { super(input); charTermAttr = addAttribute( CharTermAttribute.class ); } @Override public boolean incrementToken() throws IOException { StringBuilder buffer = new StringBuilder(); while( input.incrementToken() ) { buffer.append( charTermAttr ); } // We need to clear it either way charTermAttr.setEmpty(); if ( buffer.length() > 0 ) { charTermAttr.append( buffer ); return true; } else { return false; } } } ConcatFilterFactory.java ------------------------ package org.apache.solr.analysis; import org.apache.lucene.analysis.TokenStream; import org.apache.lucene.analysis.util.TokenFilterFactory; public class ConcatFilterFactory extends TokenFilterFactory { @Override public TokenStream create(TokenStream stream) { return new ConcatFilter(stream); } } -- Mark Bennett / New Idea Engineering, Inc. / [email protected] Direct: 408-733-0387 / Main: 866-IDEA-ENG / Cell: 408-829-6513
