Thanks Yonik for the reply. I got just a couple more questions,
1) Why does the explanantion print so many times?
2) Since my query is made up of multiple terms how do I know what term "x"
is referring to?
On 3/3/06, Yonik Seeley <yseeley@gmail.com> wrote:
>
> I think Lucene in Action does a good job of it.
> There is also a formula given in the javadoc for DefaultSimilarity
>
> http://lucene.apache.org/java/docs/api/org/apache/lucene/search/Similarity.html
>
> See my comments below (inline)
>
> On 3/2/06, Eugene <echothis@gmail.com> wrote:
> > Hi All,
> >
> > I'm not sure how to interpret the result of the toString method of
> > Explanation. I'm trying to see the values of each component of the
> > Default Similarity formula for a particular query and a doc. Given
> > below is a sample of my Explanation output. Many thanks if anyone could
> > help explain some of the values or direct me to a place that does so.
> >
> > Explanation = 0.683103 = product of:
> > 1.7077575 = sum of:
> > 0.184242 = weight(Contents:x in 78), product of:
> > 0.13565542 = queryWeight(Contents:x), product of:
> the queryWeight is queryspecific... it will have the same value
> for all documents matching the query.
> > 2.509232 = idf(docFreq=85)
> inverse document frequency... term "x" appears in 85 documents.
> > 0.054062527 = queryNorm
> queryNorm is a normalization factor... 1/sqrt(sum of all query weights
> squared)
>
> If you had a boost, it would also be multiplied into the queryWeight
> at this point.
> > 1.3581617 = fieldWeight(Contents:x in 78), product of:
> fieldWeight components are document specific.
> > 1.7320508 = tf(termFreq(Contents:x)=3)
> "x" appears 3 times in the field for this document
> > 2.509232 = idf(docFreq=85)
> same as the previous idf factor  85 documents contain "x"
> > 0.3125 = fieldNorm(field=Contents, doc=78)
> the norm is calculated at index time... it's the length normalization
> factor (1/sqrt(num tokens in this field)) multipled by any on the
> field or document.
>
> > 0.184242 = weight(Contents:x in 78), product of:
> > 0.13565542 = queryWeight(Contents:x), product of:
> > 2.509232 = idf(docFreq=85)
> > 0.054062527 = queryNorm
> > 1.3581617 = fieldWeight(Contents:x in 78), product of:
> > 1.7320508 = tf(termFreq(Contents:x)=3)
> > 2.509232 = idf(docFreq=85)
> > 0.3125 = fieldNorm(field=Contents, doc=78)
> > 0.26218253 = weight(Contents:y in 78), product of:
> > 0.16182467 = queryWeight(Contents:y), product of:
> > 2.9932873 = idf(docFreq=52)
> > 0.054062527 = queryNorm
> > 1.6201642 = fieldWeight(Contents:y in 78), product of:
> > 1.7320508 = tf(termFreq(Contents:y)=3)
> > 2.9932873 = idf(docFreq=52)
> > 0.3125 = fieldNorm(field=Contents, doc=78)
>
>
> Yonik
>
> 
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>

Regards,
Eugene
