/** jelinek-mercer with parameters */
public void testParameters() throws Exception {
  Similarity sim = getSimilarity("text_params");
  assertEquals(LMJelinekMercerSimilarity.class, sim.getClass());
  LMJelinekMercerSimilarity lm = (LMJelinekMercerSimilarity) sim;
  assertEquals(0.4f, lm.getLambda(), 0.01f);
}
 

@Before
public void setupIndex() throws IOException {
    dirUnderTest = newDirectory();
    List<Similarity> sims = Arrays.asList(
            new ClassicSimilarity(),
            new SweetSpotSimilarity(), // extends Classic
            new BM25Similarity(),
            new LMDirichletSimilarity(),
            new BooleanSimilarity(),
            new LMJelinekMercerSimilarity(0.2F),
            new AxiomaticF3LOG(0.5F, 10),
            new DFISimilarity(new IndependenceChiSquared()),
            new DFRSimilarity(new BasicModelG(), new AfterEffectB(), new NormalizationH1()),
            new IBSimilarity(new DistributionLL(), new LambdaDF(), new NormalizationH3())
        );
    similarity = sims.get(random().nextInt(sims.size()));

    indexWriterUnderTest = new RandomIndexWriter(random(), dirUnderTest, newIndexWriterConfig().setSimilarity(similarity));
    for (int i = 0; i < docs.length; i++) {
        Document doc = new Document();
        doc.add(newStringField("id", "" + i, Field.Store.YES));
        doc.add(newField("field", docs[i], Store.YES));
        indexWriterUnderTest.addDocument(doc);
    }
    indexWriterUnderTest.commit();
    indexWriterUnderTest.forceMerge(1);
    indexWriterUnderTest.flush();


    indexReaderUnderTest = indexWriterUnderTest.getReader();
    searcherUnderTest = newSearcher(indexReaderUnderTest);
    searcherUnderTest.setSimilarity(similarity);
}
 

@Inject
public LMJelinekMercerSimilarityProvider(@Assisted String name, @Assisted Settings settings) {
    super(name);
    float lambda = settings.getAsFloat("lambda", 0.1f);
    this.similarity = new LMJelinekMercerSimilarity(lambda);
}
 

@Override
public Similarity getSimilarity() {
  LMJelinekMercerSimilarity sim = new LMJelinekMercerSimilarity(lambda);
  sim.setDiscountOverlaps(discountOverlaps);
  return sim;
}
 

/** jelinek-mercer with default parameters */
public void test() throws Exception {
  assertEquals(LMJelinekMercerSimilarity.class, getSimilarity("text").getClass());
}