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SweetSpotSimilarityTest.javaAPI DocApache Lucene 2.0.05574Fri May 26 09:53:50 BST 2006org.apache.lucene.misc

SweetSpotSimilarityTest

public class SweetSpotSimilarityTest extends TestCase
Test of the SweetSpotSimilarity

Fields Summary
Constructors Summary
Methods Summary
public voidtestHyperbolicSweetSpot()

  
    SweetSpotSimilarity ss = new SweetSpotSimilarity() {
        public float tf(int freq) {
          return hyperbolicTf(freq);
        }
      };
    ss.setHyperbolicTfFactors(3.3f, 7.7f, Math.E, 5.0f);
    
    Similarity 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);
    
  
public voidtestSweetSpotLengthNorm()

  
    SweetSpotSimilarity ss = new SweetSpotSimilarity();
    ss.setLengthNormFactors(1,1,0.5f);

    Similarity d = new DefaultSimilarity();
    Similarity s = ss;


    // base case, should degrade
  
    for (int i = 1; i < 1000; i++) {
      assertEquals("base case: i="+i,
                   d.lengthNorm("foo",i), s.lengthNorm("foo",i),
                   0.0f);
    }

    // make a sweet spot
  
    ss.setLengthNormFactors(3,10,0.5f);
  
    for (int i = 3; i <=10; i++) {
      assertEquals("3,10: spot i="+i,
                   1.0f, s.lengthNorm("foo",i),
                   0.0f);
    }
  
    for (int i = 10; i < 1000; i++) {
      assertEquals("3,10: 10<x : i="+i,
                   d.lengthNorm("foo",i-9), s.lengthNorm("foo",i),
                   0.0f);
    }


    // seperate sweet spot for certain fields

    ss.setLengthNormFactors("bar",8,13, 0.5f);
    ss.setLengthNormFactors("yak",6,9, 0.5f);

  
    for (int i = 3; i <=10; i++) {
      assertEquals("f: 3,10: spot i="+i,
                   1.0f, s.lengthNorm("foo",i),
                   0.0f);
    }
    for (int i = 10; i < 1000; i++) {
      assertEquals("f: 3,10: 10<x : i="+i,
                   d.lengthNorm("foo",i-9), s.lengthNorm("foo",i),
                   0.0f);
    }
    for (int i = 8; i <=13; i++) {
      assertEquals("f: 8,13: spot i="+i,
                   1.0f, s.lengthNorm("bar",i),
                   0.0f);
    }
    for (int i = 6; i <=9; i++) {
      assertEquals("f: 6,9: spot i="+i,
                   1.0f, s.lengthNorm("yak",i),
                   0.0f);
    }
    for (int i = 13; i < 1000; i++) {
      assertEquals("f: 8,13: 13<x : i="+i,
                   d.lengthNorm("foo",i-12), s.lengthNorm("bar",i),
                   0.0f);
    }
    for (int i = 9; i < 1000; i++) {
      assertEquals("f: 6,9: 9<x : i="+i,
                   d.lengthNorm("foo",i-8), s.lengthNorm("yak",i),
                   0.0f);
    }


    // steepness

    ss.setLengthNormFactors("a",5,8,0.5f);
    ss.setLengthNormFactors("b",5,8,0.1f);

    for (int i = 9; i < 1000; i++) {
      assertTrue("s: i="+i+" : a="+ss.lengthNorm("a",i)+
                 " < b="+ss.lengthNorm("b",i),
                 ss.lengthNorm("a",i) < s.lengthNorm("b",i));
    }

  
public voidtestSweetSpotTf()

  
    SweetSpotSimilarity ss = new SweetSpotSimilarity();

    Similarity d = new DefaultSimilarity();
    Similarity 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);