1/sqrt(sumOfSquaredWeights).
+ * @throws IOException */
+ public float queryNorm(Weight weight) {
+ return (float)(1.0 / Math.sqrt(weight.sumOfSquaredWeights()));
+ }
/** Implemented as sqrt(freq). */
public float tf(float freq) {
Index: src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
===================================================================
--- src/java/org/apache/lucene/search/DisjunctionMaxQuery.java (revision 813200)
+++ src/java/org/apache/lucene/search/DisjunctionMaxQuery.java (working copy)
@@ -114,7 +114,7 @@
public float getValue() { return getBoost(); }
/* Compute the sub of squared weights of us applied to our subqueries. Used for normalization. */
- public float sumOfSquaredWeights() throws IOException {
+ public float sumOfSquaredWeights() {
float max = 0.0f, sum = 0.0f;
for (Iterator iter = weights.iterator(); iter.hasNext();) {
float sub = ((Weight) iter.next()).sumOfSquaredWeights();
Index: src/java/org/apache/lucene/search/FilteredQuery.java
===================================================================
--- src/java/org/apache/lucene/search/FilteredQuery.java (revision 813200)
+++ src/java/org/apache/lucene/search/FilteredQuery.java (working copy)
@@ -66,7 +66,7 @@
// pass these methods through to enclosed query's weight
public float getValue() { return value; }
- public float sumOfSquaredWeights() throws IOException {
+ public float sumOfSquaredWeights() {
return weight.sumOfSquaredWeights() * getBoost() * getBoost();
}
public void normalize (float v) {
Index: src/java/org/apache/lucene/search/Query.java
===================================================================
--- src/java/org/apache/lucene/search/Query.java (revision 813200)
+++ src/java/org/apache/lucene/search/Query.java (working copy)
@@ -97,8 +97,7 @@
public Weight weight(Searcher searcher) throws IOException {
Query query = searcher.rewrite(this);
Weight weight = query.createWeight(searcher);
- float sum = weight.sumOfSquaredWeights();
- float norm = getSimilarity(searcher).queryNorm(sum);
+ float norm = getSimilarity(searcher).queryNorm(weight);
weight.normalize(norm);
return weight;
}
Index: src/java/org/apache/lucene/search/Similarity.java
===================================================================
--- src/java/org/apache/lucene/search/Similarity.java (revision 813200)
+++ src/java/org/apache/lucene/search/Similarity.java (working copy)
@@ -384,7 +384,7 @@
* @see org.apache.lucene.document.Field#setBoost(float)
*/
public abstract float lengthNorm(String fieldName, int numTokens);
-
+
/** Computes the normalization value for a query given the sum of the squared
* weights of each of the query terms. This value is multiplied into the
* weight of each query term. While the classic query normalization factor is
@@ -397,9 +397,26 @@
*
* @param sumOfSquaredWeights the sum of the squares of query term weights
* @return a normalization factor for query weights
+ * @deprecated use {@link #queryNorm(Weight)}
*/
public abstract float queryNorm(float sumOfSquaredWeights);
+ /** Computes the normalization value for a query given the sum of the squared
+ * weights of each of the query terms. This value is multiplied into the
+ * weight of each query term. While the classic query normalization factor is
+ * computed as 1/sqrt(sumOfSquaredWeights), other implementations might
+ * completely ignore sumOfSquaredWeights (ie return 1).
+ *
+ * This does not affect ranking, but the default implementation does make scores + * from different queries more comparable than they would be by eliminating the + * magnitude of the Query vector as a factor in the score. + * + * @param weight the Query Weight + * @return a normalization factor for query weights + * @throws IOException + */ + public abstract float queryNorm(Weight weight); + /** Encodes a normalization factor for storage in an index. * *
The encoding uses a three-bit mantissa, a five-bit exponent, and Index: src/java/org/apache/lucene/search/SimilarityDelegator.java =================================================================== --- src/java/org/apache/lucene/search/SimilarityDelegator.java (revision 813200) +++ src/java/org/apache/lucene/search/SimilarityDelegator.java (working copy) @@ -45,6 +45,10 @@ public float queryNorm(float sumOfSquaredWeights) { return delegee.queryNorm(sumOfSquaredWeights); } + + public float queryNorm(Weight weight) { + return delegee.queryNorm(weight); + } public float tf(float freq) { return delegee.tf(freq); Index: src/java/org/apache/lucene/search/Weight.java =================================================================== --- src/java/org/apache/lucene/search/Weight.java (revision 813200) +++ src/java/org/apache/lucene/search/Weight.java (working copy) @@ -100,7 +100,7 @@ boolean topScorer) throws IOException; /** The sum of squared weights of contained query clauses. */ - public abstract float sumOfSquaredWeights() throws IOException; + public abstract float sumOfSquaredWeights(); /** * Returns true iff this implementation scores docs only out of order. This Index: src/java/org/apache/lucene/search/function/CustomScoreQuery.java =================================================================== --- src/java/org/apache/lucene/search/function/CustomScoreQuery.java (revision 813200) +++ src/java/org/apache/lucene/search/function/CustomScoreQuery.java (working copy) @@ -298,7 +298,7 @@ } /*(non-Javadoc) @see org.apache.lucene.search.Weight#sumOfSquaredWeights() */ - public float sumOfSquaredWeights() throws IOException { + public float sumOfSquaredWeights() { float sum = subQueryWeight.sumOfSquaredWeights(); for(int i = 0; i < valSrcWeights.length; i++) { if (qStrict) { Index: src/java/org/apache/lucene/search/function/ValueSourceQuery.java =================================================================== --- src/java/org/apache/lucene/search/function/ValueSourceQuery.java (revision 813200) +++ src/java/org/apache/lucene/search/function/ValueSourceQuery.java (working copy) @@ -82,7 +82,7 @@ } /*(non-Javadoc) @see org.apache.lucene.search.Weight#sumOfSquaredWeights() */ - public float sumOfSquaredWeights() throws IOException { + public float sumOfSquaredWeights() { queryWeight = getBoost(); return queryWeight * queryWeight; } Index: src/java/org/apache/lucene/search/spans/SpanWeight.java =================================================================== --- src/java/org/apache/lucene/search/spans/SpanWeight.java (revision 813200) +++ src/java/org/apache/lucene/search/spans/SpanWeight.java (working copy) @@ -52,7 +52,7 @@ public Query getQuery() { return query; } public float getValue() { return value; } - public float sumOfSquaredWeights() throws IOException { + public float sumOfSquaredWeights() { queryWeight = idf * query.getBoost(); // compute query weight return queryWeight * queryWeight; // square it } Index: src/test/org/apache/lucene/index/TestOmitTf.java =================================================================== --- src/test/org/apache/lucene/index/TestOmitTf.java (revision 813200) +++ src/test/org/apache/lucene/index/TestOmitTf.java (working copy) @@ -33,6 +33,7 @@ import org.apache.lucene.search.Searcher; import org.apache.lucene.search.Similarity; import org.apache.lucene.search.TermQuery; +import org.apache.lucene.search.Weight; import org.apache.lucene.search.BooleanClause.Occur; import org.apache.lucene.store.Directory; import org.apache.lucene.store.MockRAMDirectory; @@ -43,6 +44,7 @@ public static class SimpleSimilarity extends Similarity { public float lengthNorm(String field, int numTerms) { return 1.0f; } public float queryNorm(float sumOfSquaredWeights) { return 1.0f; } + public float queryNorm(Weight weight) { return 1.0f; } public float tf(float freq) { return freq; } Index: src/test/org/apache/lucene/search/JustCompileSearch.java =================================================================== --- src/test/org/apache/lucene/search/JustCompileSearch.java (revision 813200) +++ src/test/org/apache/lucene/search/JustCompileSearch.java (working copy) @@ -375,6 +375,10 @@ public float lengthNorm(String fieldName, int numTokens) { throw new UnsupportedOperationException(UNSUPPORTED_MSG); } + + public float queryNorm(Weight weight) { + throw new UnsupportedOperationException(UNSUPPORTED_MSG); + } public float queryNorm(float sumOfSquaredWeights) { throw new UnsupportedOperationException(UNSUPPORTED_MSG); @@ -446,7 +450,7 @@ throw new UnsupportedOperationException(UNSUPPORTED_MSG); } - public float sumOfSquaredWeights() throws IOException { + public float sumOfSquaredWeights() { throw new UnsupportedOperationException(UNSUPPORTED_MSG); } Index: src/test/org/apache/lucene/search/TestSimilarity.java =================================================================== --- src/test/org/apache/lucene/search/TestSimilarity.java (revision 813200) +++ src/test/org/apache/lucene/search/TestSimilarity.java (working copy) @@ -48,6 +48,7 @@ public float idf(Collection terms, Searcher searcher) { return 1.0f; } public float idf(int docFreq, int numDocs) { return 1.0f; } public float coord(int overlap, int maxOverlap) { return 1.0f; } + public float queryNorm(Weight weight) { return 1.0f; } } public void testSimilarity() throws Exception {