@Test
  public void exact() throws Exception {
    EvalFunc<DataBag> func = new FrequentStringsSketchToEstimates();
    ItemsSketch<String> sketch = new ItemsSketch<String>(8);
    sketch.update("a");
    sketch.update("a");
    sketch.update("b");
    Tuple inputTuple =
        PigUtil.objectsToTuple(new DataByteArray(sketch.toByteArray(new ArrayOfStringsSerDe())));
    DataBag bag = func.exec(inputTuple);
    Assert.assertNotNull(bag);
    Assert.assertEquals(bag.size(), 2);

    Iterator<Tuple> it = bag.iterator();
    Tuple tuple1 = it.next();
    Assert.assertEquals(tuple1.size(), 4);
    Assert.assertEquals((String) tuple1.get(0), "a");
    Assert.assertEquals((long) tuple1.get(1), 2L);
    Assert.assertEquals((long) tuple1.get(2), 2L);
    Assert.assertEquals((long) tuple1.get(3), 2L);

    Tuple tuple2 = it.next();
    Assert.assertEquals(tuple2.size(), 4);
    Assert.assertEquals((String) tuple2.get(0), "b");
    Assert.assertEquals((long) tuple2.get(1), 1L);
    Assert.assertEquals((long) tuple2.get(2), 1L);
    Assert.assertEquals((long) tuple2.get(3), 1L);
  }
  @Test
  public void estimation() throws Exception {
    ItemsSketch<String> sketch = new ItemsSketch<String>(8);
    sketch.update("1", 1000);
    sketch.update("2", 500);
    sketch.update("3", 200);
    sketch.update("4", 100);
    sketch.update("5", 50);
    sketch.update("6", 20);
    sketch.update("7", 10);
    sketch.update("8", 5);
    sketch.update("9", 2);
    sketch.update("10");
    Tuple inputTuple =
        PigUtil.objectsToTuple(new DataByteArray(sketch.toByteArray(new ArrayOfStringsSerDe())));

    EvalFunc<DataBag> func1 = new FrequentStringsSketchToEstimates("NO_FALSE_POSITIVES");
    DataBag bag1 = func1.exec(inputTuple);
    Assert.assertNotNull(bag1);
    Assert.assertTrue(bag1.size() < 10);

    EvalFunc<DataBag> func2 = new FrequentStringsSketchToEstimates("NO_FALSE_NEGATIVES");
    DataBag bag2 = func2.exec(inputTuple);
    Assert.assertNotNull(bag2);
    Assert.assertTrue(bag2.size() < 10);

    Assert.assertTrue(bag1.size() < bag2.size());
  }