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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