List of itemSimilarity() Examples

Examples of itemSimilarity()

org.apache.mahout.cf.taste.impl.similarity.GenericItemSimilarity.itemSimilarity()

Returns the similarity between two items. Note that similarity is assumed to be symmetric, that itemSimilarity(item1, item2) == itemSimilarity(item2, item1), and that itemSimilarity(item1, item1) == 1.0 for all items.
@param itemID1 first item @param itemID2 second item @return similarity between the two
org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

Returns the degree of similarity, of two items, based on the preferences that users have expressed for the items.
@param itemID1 first item ID @param itemID2 second item ID @return similarity between the items, in [-1,1] @throws TasteException if an error occurs while accessing the data

Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

                    {1.0, 2.0},
                    {2.0, 5.0},
                    {3.0, 6.0},
            });
    ItemSimilarity itemSimilarity = new PearsonCorrelationSimilarity(dataModel, Weighting.WEIGHTED);
    double correlation = itemSimilarity.itemSimilarity(0, 1);
    assertCorrelationEquals(0.9901922307076306, correlation);
  }


  public void testRefresh() throws Exception {
    // Make sure this doesn't throw an exception

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

                    {1.0, 2.0},
                    {2.0, 5.0},
                    {3.0, 6.0},
            });
    ItemSimilarity itemSimilarity = new EuclideanDistanceSimilarity(dataModel, Weighting.WEIGHTED);
    double correlation = itemSimilarity.itemSimilarity(0, 1);
    assertCorrelationEquals(0.8974062142054332, correlation);
  }


  public void testRefresh() throws TasteException {
    // Make sure this doesn't throw an exception

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

                    {2.0, 5.0},
                    {3.0, 6.0},
            });
    ItemSimilarity otherSimilarity = new PearsonCorrelationSimilarity(dataModel);
    ItemSimilarity itemSimilarity = new GenericItemSimilarity(otherSimilarity, dataModel);
    assertCorrelationEquals(1.0, itemSimilarity.itemSimilarity(0, 0));
    assertCorrelationEquals(0.960768922830523, itemSimilarity.itemSimilarity(0, 1));
  }


}

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

                    {3.0, 6.0},
            });
    ItemSimilarity otherSimilarity = new PearsonCorrelationSimilarity(dataModel);
    ItemSimilarity itemSimilarity = new GenericItemSimilarity(otherSimilarity, dataModel);
    assertCorrelationEquals(1.0, itemSimilarity.itemSimilarity(0, 0));
    assertCorrelationEquals(0.960768922830523, itemSimilarity.itemSimilarity(0, 1));
  }


}

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()


  @Test
  public void testLoadFromFile() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile);


    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);


    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

                    {1.0, 2.0},
                    {2.0, 5.0},
                    {3.0, 6.0},
            });
    ItemSimilarity itemSimilarity = new EuclideanDistanceSimilarity(dataModel, Weighting.WEIGHTED);
    double correlation = itemSimilarity.itemSimilarity(0, 1);
    assertCorrelationEquals(0.889954122647528, correlation);
  }


  @Test
  public void testRefresh() throws TasteException {

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

  @Test
  public void testLoadFromFile() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile);


    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);


    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

  public void testLoadFromFile() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile);


    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);


    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));


    double[] valuesForOne = similarity.itemSimilarities(1L, new long[] { 5L, 7L });

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

    ItemSimilarity similarity = new FileItemSimilarity(testFile);


    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);


    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));


    double[] valuesForOne = similarity.itemSimilarities(1L, new long[] { 5L, 7L });
    assertNotNull(valuesForOne);

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Examples of org.apache.mahout.cf.taste.similarity.ItemSimilarity.itemSimilarity()

    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);


    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));


    double[] valuesForOne = similarity.itemSimilarities(1L, new long[] { 5L, 7L });
    assertNotNull(valuesForOne);
    assertEquals(2, valuesForOne.length);
    assertEquals(0.125, valuesForOne[0], EPSILON);

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