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Posted to solr-user@lucene.apache.org by elisabeth benoit <el...@gmail.com> on 2011/11/15 09:03:52 UTC

NGramFilterFactory - proximity and percentage of ngrams found

Hello,

I'm trying to use NGramFilterFactory for spell correction. I have three
questions.

1) I use an edismax request handler. In this case, what is the relation
between my ngrams and my default operator (q.op), if there is any?

2) Is there a way to control the proximity and percentage of ngrams found?
I figured I could use pf, pf2 and pf3 parameters, but is there something
more general?

3) If I want to favorise begining of words, is there a way to do it with
ngrams (for instance, if there was an option to add two spaces at begining
of every word, with ngrams size 3, "paris" would result in "  p", " pa",
"par", "ari", "ris") or should I use Edge factory?

Thanks,
Elisabeth

Re: NGramFilterFactory - proximity and percentage of ngrams found

Posted by Erick Erickson <er...@gmail.com>.
Well, I can have  ago at two of them...

(1) there isn't any relationship here. Although the q.op parameter can
     be used, see:
http://wiki.apache.org/solr/DisMaxQParserPlugin#mm_.28Minimum_.27Should.27_Match.29

(2) I have no real clue

(3) Probably the edge factory would be good here, although it's possible
     that this will over-correct for your situation.

Best
Erick

On Tue, Nov 15, 2011 at 3:03 AM, elisabeth benoit
<el...@gmail.com> wrote:
> Hello,
>
> I'm trying to use NGramFilterFactory for spell correction. I have three
> questions.
>
> 1) I use an edismax request handler. In this case, what is the relation
> between my ngrams and my default operator (q.op), if there is any?
>
> 2) Is there a way to control the proximity and percentage of ngrams found?
> I figured I could use pf, pf2 and pf3 parameters, but is there something
> more general?
>
> 3) If I want to favorise begining of words, is there a way to do it with
> ngrams (for instance, if there was an option to add two spaces at begining
> of every word, with ngrams size 3, "paris" would result in "  p", " pa",
> "par", "ari", "ris") or should I use Edge factory?
>
> Thanks,
> Elisabeth
>