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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.misc;
import org.apache.lucene.search.similarities.DefaultSimilarity;
import org.apache.lucene.search.similarities.PerFieldSimilarityWrapper;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.search.similarities.TFIDFSimilarity;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.index.FieldInvertState;
/**
* Test of the SweetSpotSimilarity
*/
public class SweetSpotSimilarityTest extends LuceneTestCase {
public static float computeAndDecodeNorm(SweetSpotSimilarity decode, Similarity encode, FieldInvertState state) {
return decode.decodeNormValue(computeAndGetNorm(encode, state));
}
public static byte computeAndGetNorm(Similarity s, FieldInvertState state) {
return (byte) s.computeNorm(state);
}
public void testSweetSpotComputeNorm() {
final SweetSpotSimilarity ss = new SweetSpotSimilarity();
ss.setLengthNormFactors(1,1,0.5f,true);
Similarity d = new DefaultSimilarity();
Similarity s = ss;
// base case, should degrade
FieldInvertState invertState = new FieldInvertState("bogus");
invertState.setBoost(1.0f);
for (int i = 1; i < 1000; i++) {
invertState.setLength(i);
assertEquals("base case: i="+i,
computeAndGetNorm(d, invertState),
computeAndGetNorm(s, invertState),
0.0f);
}
// make a sweet spot
ss.setLengthNormFactors(3,10,0.5f,true);
for (int i = 3; i <=10; i++) {
invertState.setLength(i);
assertEquals("3,10: spot i="+i,
1.0f,
computeAndDecodeNorm(ss, ss, invertState),
0.0f);
}
for (int i = 10; i < 1000; i++) {
invertState.setLength(i-9);
final byte normD = computeAndGetNorm(d, invertState);
invertState.setLength(i);
final byte normS = computeAndGetNorm(s, invertState);
assertEquals("3,10: 10<x : i="+i,
normD,
normS,
0.0f);
}
// separate sweet spot for certain fields
final SweetSpotSimilarity ssBar = new SweetSpotSimilarity();
ssBar.setLengthNormFactors(8,13, 0.5f, false);
final SweetSpotSimilarity ssYak = new SweetSpotSimilarity();
ssYak.setLengthNormFactors(6,9, 0.5f, false);
final SweetSpotSimilarity ssA = new SweetSpotSimilarity();
ssA.setLengthNormFactors(5,8,0.5f, false);
final SweetSpotSimilarity ssB = new SweetSpotSimilarity();
ssB.setLengthNormFactors(5,8,0.1f, false);
Similarity sp = new PerFieldSimilarityWrapper() {
@Override
public Similarity get(String field) {
if (field.equals("bar"))
return ssBar;
else if (field.equals("yak"))
return ssYak;
else if (field.equals("a"))
return ssA;
else if (field.equals("b"))
return ssB;
else
return ss;
}
};
invertState = new FieldInvertState("foo");
invertState.setBoost(1.0f);
for (int i = 3; i <=10; i++) {
invertState.setLength(i);
assertEquals("f: 3,10: spot i="+i,
1.0f,
computeAndDecodeNorm(ss, sp, invertState),
0.0f);
}
for (int i = 10; i < 1000; i++) {
invertState.setLength(i-9);
final byte normD = computeAndGetNorm(d, invertState);
invertState.setLength(i);
final byte normS = computeAndGetNorm(sp, invertState);
assertEquals("f: 3,10: 10<x : i="+i,
normD,
normS,
0.0f);
}
invertState = new FieldInvertState("bar");
invertState.setBoost(1.0f);
for (int i = 8; i <=13; i++) {
invertState.setLength(i);
assertEquals("f: 8,13: spot i="+i,
1.0f,
computeAndDecodeNorm(ss, sp, invertState),
0.0f);
}
invertState = new FieldInvertState("yak");
invertState.setBoost(1.0f);
for (int i = 6; i <=9; i++) {
invertState.setLength(i);
assertEquals("f: 6,9: spot i="+i,
1.0f,
computeAndDecodeNorm(ss, sp, invertState),
0.0f);
}
invertState = new FieldInvertState("bar");
invertState.setBoost(1.0f);
for (int i = 13; i < 1000; i++) {
invertState.setLength(i-12);
final byte normD = computeAndGetNorm(d, invertState);
invertState.setLength(i);
final byte normS = computeAndGetNorm(sp, invertState);
assertEquals("f: 8,13: 13<x : i="+i,
normD,
normS,
0.0f);
}
invertState = new FieldInvertState("yak");
invertState.setBoost(1.0f);
for (int i = 9; i < 1000; i++) {
invertState.setLength(i-8);
final byte normD = computeAndGetNorm(d, invertState);
invertState.setLength(i);
final byte normS = computeAndGetNorm(sp, invertState);
assertEquals("f: 6,9: 9<x : i="+i,
normD,
normS,
0.0f);
}
// steepness
for (int i = 9; i < 1000; i++) {
invertState = new FieldInvertState("a");
invertState.setBoost(1.0f);
invertState.setLength(i);
final byte normSS = computeAndGetNorm(sp, invertState);
invertState = new FieldInvertState("b");
invertState.setBoost(1.0f);
invertState.setLength(i);
final byte normS = computeAndGetNorm(sp, invertState);
assertTrue("s: i="+i+" : a="+normSS+
" < b="+normS,
normSS < normS);
}
}
public void testSweetSpotTf() {
SweetSpotSimilarity ss = new SweetSpotSimilarity();
TFIDFSimilarity d = new DefaultSimilarity();
TFIDFSimilarity s = ss;
// tf equal
ss.setBaselineTfFactors(0.0f, 0.0f);
for (int i = 1; i < 1000; i++) {
assertEquals("tf: i="+i,
d.tf(i), s.tf(i), 0.0f);
}
// tf higher
ss.setBaselineTfFactors(1.0f, 0.0f);
for (int i = 1; i < 1000; i++) {
assertTrue("tf: i="+i+" : d="+d.tf(i)+
" < s="+s.tf(i),
d.tf(i) < s.tf(i));
}
// tf flat
ss.setBaselineTfFactors(1.0f, 6.0f);
for (int i = 1; i <=6; i++) {
assertEquals("tf flat1: i="+i, 1.0f, s.tf(i), 0.0f);
}
ss.setBaselineTfFactors(2.0f, 6.0f);
for (int i = 1; i <=6; i++) {
assertEquals("tf flat2: i="+i, 2.0f, s.tf(i), 0.0f);
}
for (int i = 6; i <=1000; i++) {
assertTrue("tf: i="+i+" : s="+s.tf(i)+
" < d="+d.tf(i),
s.tf(i) < d.tf(i));
}
// stupidity
assertEquals("tf zero", 0.0f, s.tf(0), 0.0f);
}
public void testHyperbolicSweetSpot() {
SweetSpotSimilarity ss = new SweetSpotSimilarity() {
@Override
public float tf(float freq) {
return hyperbolicTf(freq);
}
};
ss.setHyperbolicTfFactors(3.3f, 7.7f, Math.E, 5.0f);
TFIDFSimilarity s = ss;
for (int i = 1; i <=1000; i++) {
assertTrue("MIN tf: i="+i+" : s="+s.tf(i),
3.3f <= s.tf(i));
assertTrue("MAX tf: i="+i+" : s="+s.tf(i),
s.tf(i) <= 7.7f);
}
assertEquals("MID tf", 3.3f+(7.7f - 3.3f)/2.0f, s.tf(5), 0.00001f);
// stupidity
assertEquals("tf zero", 0.0f, s.tf(0), 0.0f);
}
}