CoMomentTest.java

/**
 * Copyright (c) 2013, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. licenses this file to you under the Apache License,
 * Version 2.0 (the "License"). You may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for
 * the specific language governing permissions and limitations under the
 * License.
 */
package com.cloudera.science.ml.parallel.covariance;

import org.junit.Test;

import java.util.Random;

import static org.junit.Assert.assertEquals;

public class CoMomentTest {

  private Random r = new Random(1729L);

  @Test
  public void testMerge() throws Exception {
    CoMoment a = new CoMoment();
    CoMoment b = new CoMoment();
    CoMoment c = new CoMoment();
    for (int i = 0; i < 100; i++) {
      double r1 = r.nextDouble(), r2 = r.nextDouble();
      c.update(r1, r2);
      if (i % 2 == 0) {
        a.update(r1, r2);
      } else {
        b.update(r1, r2);
      }
    }
    assertEquals(c, a.merge(b));
    assertEquals(c, b.merge(a));
  }

  @Test
  public void testMergeZero() throws Exception {
    CoMoment cm = new CoMoment();
    for (int i = 0; i < 10; i++) {
      cm.update(r.nextDouble(), r.nextDouble());
    }
    assertEquals(cm, cm.merge(new CoMoment()));
    assertEquals(cm, new CoMoment().merge(cm));
  }
}