@Test
public void testPlus() {

    NewComponentStatisticsAggregator agg1 = new NewComponentStatisticsAggregator();
    NewComponentStatisticsAggregator agg2 = new NewComponentStatisticsAggregator();
    int rowCount = 10;
    for (int i = 0; i < rowCount; i++)
        agg1.add(VectorUtils.of(0, 1, 2), i % 2 == 0);
    for (int i = 0; i < rowCount; i++)
        agg2.add(VectorUtils.of(2, 1, 0), i % 2 == 1);
    NewComponentStatisticsAggregator sum = agg1.plus(agg2);
    assertEquals(rowCount, sum.rowCountForNewCluster());
    assertEquals(rowCount * 2, sum.totalRowCount());
    assertArrayEquals(new double[] {1, 1, 1}, sum.mean().asArray(), 1e-4);
}