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()

                    {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 testNoRefreshAfterFileUpdate() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile, 0L);


    /* call a method to make sure the original file is loaded*/
    similarity.itemSimilarity(1L, 5L);


    /* change the underlying file,
     * we have to wait at least a second to see the change in the file's lastModified timestamp */
    Thread.sleep(2000L);
    writeLines(testFile, changedData);

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

     * we have to wait at least a second to see the change in the file's lastModified timestamp */
    Thread.sleep(2000L);
    writeLines(testFile, changedData);


    /* we shouldn't see any changes in the data as we have not yet refreshed */
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
  }


  @Test

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

    Thread.sleep(2000L);
    writeLines(testFile, changedData);


    /* we shouldn't see any changes in the data as we have not yet refreshed */
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
  }


  @Test
  public void testRefreshAfterFileUpdate() throws Exception {

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

    writeLines(testFile, changedData);


    /* we shouldn't see any changes in the data as we have not yet refreshed */
    assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
    assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
    assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
  }


  @Test
  public void testRefreshAfterFileUpdate() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile, 0L);

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

  @Test
  public void testRefreshAfterFileUpdate() throws Exception {
    ItemSimilarity similarity = new FileItemSimilarity(testFile, 0L);


    /* call a method to make sure the original file is loaded */
    similarity.itemSimilarity(1L, 5L);


    /* change the underlying file,
     * we have to wait at least a second to see the change in the file's lastModified timestamp */
    Thread.sleep(2000L);
    writeLines(testFile, changedData);

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

    writeLines(testFile, changedData);


    similarity.refresh(null);


    /* 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)));

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


    similarity.refresh(null);


    /* 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);

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

    similarity.refresh(null);


    /* 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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