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()


    /* we should now see the changes in the data */
    assertEquals(0.9, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.9, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);


    assertFalse(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
    assertEquals(0.112, similarity.itemSimilarity(7L, 8L), EPSILON);
    assertEquals(0.112, similarity.itemSimilarity(8L, 7L), EPSILON);
  }

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

    assertEquals(0.9, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.9, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);


    assertFalse(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
    assertEquals(0.112, similarity.itemSimilarity(7L, 8L), EPSILON);
    assertEquals(0.112, similarity.itemSimilarity(8L, 7L), EPSILON);
  }


  @Test(expected = IllegalArgumentException.class)

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

    assertEquals(0.9, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
    assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);


    assertFalse(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
    assertEquals(0.112, similarity.itemSimilarity(7L, 8L), EPSILON);
    assertEquals(0.112, similarity.itemSimilarity(8L, 7L), EPSILON);
  }


  @Test(expected = IllegalArgumentException.class)
  public void testFileNotFoundExceptionForNonExistingFile() throws Exception {

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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);


    assertFalse(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
    assertEquals(0.112, similarity.itemSimilarity(7L, 8L), EPSILON);
    assertEquals(0.112, similarity.itemSimilarity(8L, 7L), EPSILON);
  }


  @Test(expected = IllegalArgumentException.class)
  public void testFileNotFoundExceptionForNonExistingFile() throws Exception {
    new FileItemSimilarity(new File("xKsdfksdfsdf"));

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

    User user1 = getUser("test1", 1.0, 2.0);
    User user2 = getUser("test2", 2.0, 5.0);
    User user3 = getUser("test3", 3.0, 6.0);
    DataModel dataModel = getDataModel(user1, user2, user3);
    ItemSimilarity itemSimilarity = new EuclideanDistanceSimilarity(dataModel, Weighting.WEIGHTED);
    double correlation = itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("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()

    User user1 = getUser("test1", 1.0, 2.0);
    User user2 = getUser("test2", 2.0, 5.0);
    User user3 = getUser("test3", 3.0, 6.0);
    DataModel dataModel = getDataModel(user1, user2, user3);
    ItemSimilarity itemSimilarity = new PearsonCorrelationSimilarity(dataModel, Weighting.WEIGHTED);
    double correlation = itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("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()

    User user3 = getUser("test3", 3.0, 6.0);
    DataModel dataModel = getDataModel(user1, user2, user3);
    ItemSimilarity otherSimilarity = new PearsonCorrelationSimilarity(dataModel);
    ItemSimilarity itemSimilarity = new GenericItemSimilarity(otherSimilarity, dataModel);
    assertCorrelationEquals(1.0,
                            itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("0")));
    assertCorrelationEquals(0.960768922830523,
                            itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("1")));
  }


}

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

    ItemSimilarity otherSimilarity = new PearsonCorrelationSimilarity(dataModel);
    ItemSimilarity itemSimilarity = new GenericItemSimilarity(otherSimilarity, dataModel);
    assertCorrelationEquals(1.0,
                            itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("0")));
    assertCorrelationEquals(0.960768922830523,
                            itemSimilarity.itemSimilarity(dataModel.getItem("0"), dataModel.getItem("1")));
  }


}

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


    EasyMock.replay(dataSource, connection, statement, resultSet);


    ItemSimilarity similarity = new MySQLJDBCInMemoryItemSimilarity(dataSource);


    assertEquals(0.5, similarity.itemSimilarity(1L, 2L), EPSILON);
    assertEquals(0.4, similarity.itemSimilarity(1L, 3L), EPSILON);
    assertEquals(0.1, similarity.itemSimilarity(3L, 4L), EPSILON);
    assertTrue(Double.isNaN(similarity.itemSimilarity(1L, 4L)));


    EasyMock.verify(dataSource, connection, statement, resultSet);

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

    EasyMock.replay(dataSource, connection, statement, resultSet);


    ItemSimilarity similarity = new MySQLJDBCInMemoryItemSimilarity(dataSource);


    assertEquals(0.5, similarity.itemSimilarity(1L, 2L), EPSILON);
    assertEquals(0.4, similarity.itemSimilarity(1L, 3L), EPSILON);
    assertEquals(0.1, similarity.itemSimilarity(3L, 4L), EPSILON);
    assertTrue(Double.isNaN(similarity.itemSimilarity(1L, 4L)));


    EasyMock.verify(dataSource, connection, statement, resultSet);
  }

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