@Test
public void testAdd() {

    assertArrayEquals(new double[] {0.781, 0.468}, aggregator1.mean().asArray(), 1e-2);
    assertArrayEquals(new double[] {0.5, 0.5}, aggregator2.mean().asArray(), 1e-2);
    assertEquals(0.4, aggregator1.clusterProb(), 1e-4);
    assertEquals(1.0, aggregator2.clusterProb(), 1e-4);
}