Yes, for the other methods (except scorePayload), I just use delegate to
the corresponding method in DefaultSimilarity. The reason is that I
don't have a way to trigger off the field name for these others. For me,
I really only need to distinguish between DefaultSimilarity and
PayloadSimilarity (which needs to be triggered for certain fields in my
index), so I overrode the scorePayloads method also in the same Map
driven way.
On Tue, 2011-03-01 at 23:28 +0100, Patrick Diviacco wrote:
> I see, but I don't get one thing... you are actually customizing only
> normLenght method but not all the other methods that are calculating
> the similarity scores...
>
>
> those methods are called and they have the implementation you have in
> DefaultSimilarityClass.. right ?
>
>
>
>
> On 1 March 2011 21:12, Sujit Pal <sujit....@comcast.net> wrote:
> One way to do this currently is to build a per field
> similarity wrapper
> (that triggers off the field name). I believe there is some
> work going
> on with Lucene Similarity that would make it pluggable for
> this sort of
> stuff, but in the meantime, this is what I did:
>
> public class MyPerFieldSimilarityWrapper extends Similarity {
>
> public MyPerFieldSimilarityWrapper() {
> this.defaultSimilarity = new DefaultSimilarity();
> this.fieldSimilarityMap = new HashMap<String,Similarity>();
> this.fieldSimilarityMap.put("fieldA", new
> FieldASimilarity());
> ...
> }
>
> @Override
> public float lengthNorm(String fieldName, int numTokens) {
> Similarity sim = fieldSimilarityMap.get(fieldName);
> if (sim == null) {
> return defaultSimilarity.lengthNorm(fieldName,
> numTokens);
> } else {
> return sim.lengthNorm(fieldName, numTokens);
> }
> }
> // same for scorePayload. For the others, I just delegate
> // to defaultSimilarity (all I really need is scorePayload in
> // my case).
> }
>
> and in the schema.xml, I just set this class to be the
> similarity class:
> <similarity
> class="com.mycompany.MyPerFieldSimilarityWrapper"/>
>
> hth
> -sujit
>
>
> On Tue, 2011-03-01 at 20:41 +0100, Patrick Diviacco wrote:
> > I need to define different similarity scores per document
> field.
> >
> > For example for field A I want to use Lucene tf.idf score,
> for the numerical
> > field B I want to use a different metric (difference between
> values) and so
> > on...
> >
> > thanks
>
>
>
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