1/sqrt(sumOfSquaredWeights). */
- public float queryNorm(float sumOfSquaredWeights) {
- return (float)(1.0 / Math.sqrt(sumOfSquaredWeights));
- }
/** Implemented as sqrt(freq). */
public float tf(float freq) {
Index: src/java/org/apache/lucene/search/Query.java
===================================================================
--- src/java/org/apache/lucene/search/Query.java (revision 813416)
+++ 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 813416)
+++ src/java/org/apache/lucene/search/Similarity.java (working copy)
@@ -397,8 +397,48 @@
*
* @param sumOfSquaredWeights the sum of the squares of query term weights
* @return a normalization factor for query weights
+ * @deprecated use {@link #queryNorm(Weight)}
+ */
+ public float queryNorm(float sumOfSquaredWeights) {
+ return (float)(1.0 / Math.sqrt(sumOfSquaredWeights));
+ }
+
+
+ /** Computes the normalization value for a query given the Weight. 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
+ * @throws IOException
*/
- public abstract float queryNorm(float sumOfSquaredWeights);
+ public float queryNorm(Weight weight) throws IOException {
+ if (supportedMethods.overridesQueryNorm) {
+ float sum;
+
+ sum = weight.sumOfSquaredWeights();
+
+ return queryNorm(sum);
+ } else {
+ // Implemented as 1/sqrt(sumOfSquaredWeights).
+ float sum;
+ try {
+ sum = weight.sumOfSquaredWeights();
+ } catch (IOException e) {
+ // this should not need to throw an IOException,
+ // but if it does, we will convert to runtime
+ throw new RuntimeException();
+ }
+ return (float) (1.0 / Math.sqrt(sum));
+ }
+ }
+
/** Encodes a normalization factor for storage in an index.
*
@@ -694,11 +734,12 @@
/** @deprecated Remove this when old API is removed! */
private static final class MethodSupport implements Serializable {
- final boolean overridesCollectionIDF, overridesTermIDF;
+ final boolean overridesCollectionIDF, overridesTermIDF, overridesQueryNorm;
MethodSupport(Class clazz) {
overridesCollectionIDF = isMethodOverridden(clazz, "idf", C_IDF_METHOD_PARAMS);
overridesTermIDF = isMethodOverridden(clazz, "idf", T_IDF_METHOD_PARAMS);
+ overridesQueryNorm = isMethodOverridden(clazz, "queryNorm", QN_METHOD_PARAMS);
}
private static boolean isMethodOverridden(Class clazz, String name, Class[] params) {
@@ -714,6 +755,10 @@
/** @deprecated Remove this when old API is removed! */
private static final Class[] C_IDF_METHOD_PARAMS = new Class[]{Collection.class, Searcher.class};
+
+ /** @deprecated Remove this when old API is removed! */
+ private static final Class[] QN_METHOD_PARAMS = new Class[]{float.class};
+
}
/** @deprecated Remove this when old API is removed! */
Index: src/java/org/apache/lucene/search/SimilarityDelegator.java
===================================================================
--- src/java/org/apache/lucene/search/SimilarityDelegator.java (revision 813416)
+++ src/java/org/apache/lucene/search/SimilarityDelegator.java (working copy)
@@ -1,5 +1,7 @@
package org.apache.lucene.search;
+import java.io.IOException;
+
import org.apache.lucene.index.FieldInvertState;
/**
@@ -45,6 +47,10 @@
public float queryNorm(float sumOfSquaredWeights) {
return delegee.queryNorm(sumOfSquaredWeights);
}
+
+ public float queryNorm(Weight weight) throws IOException {
+ return delegee.queryNorm(weight);
+ }
public float tf(float freq) {
return delegee.tf(freq);
Index: src/test/org/apache/lucene/search/JustCompileSearch.java
===================================================================
--- src/test/org/apache/lucene/search/JustCompileSearch.java (revision 813416)
+++ src/test/org/apache/lucene/search/JustCompileSearch.java (working copy)
@@ -375,8 +375,8 @@
public float lengthNorm(String fieldName, int numTokens) {
throw new UnsupportedOperationException(UNSUPPORTED_MSG);
}
-
- public float queryNorm(float sumOfSquaredWeights) {
+
+ public float queryNorm(Weight weight) {
throw new UnsupportedOperationException(UNSUPPORTED_MSG);
}
@@ -446,7 +446,7 @@
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 813416)
+++ 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 {