/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License 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 org.apache.mahout.cf.taste.impl.common;
import org.apache.mahout.cf.taste.impl.TasteTestCase;
import org.junit.Test;
/**
* <p>Tests {@link WeightedRunningAverage} and {@link WeightedRunningAverageAndStdDev}.</p>
*/
public final class WeightedRunningAverageTest extends TasteTestCase {
@Test
public void testWeighted() {
WeightedRunningAverage runningAverage = new WeightedRunningAverage();
assertEquals(0, runningAverage.getCount());
assertTrue(Double.isNaN(runningAverage.getAverage()));
runningAverage.addDatum(1.0, 2.0);
assertEquals(1.0, runningAverage.getAverage(), EPSILON);
runningAverage.addDatum(1.0);
assertEquals(1.0, runningAverage.getAverage(), EPSILON);
runningAverage.addDatum(8.0, 0.5);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
runningAverage.addDatum(-4.0);
assertEquals(2.0/3.0, runningAverage.getAverage(), EPSILON);
runningAverage.removeDatum(-4.0);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
runningAverage.removeDatum(2.0, 2.0);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
runningAverage.changeDatum(0.0);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
runningAverage.changeDatum(4.0, 0.5);
assertEquals(5.0/1.5, runningAverage.getAverage(), EPSILON);
}
@Test
public void testWeightedAndStdDev() {
WeightedRunningAverageAndStdDev runningAverage = new WeightedRunningAverageAndStdDev();
assertEquals(0, runningAverage.getCount());
assertTrue(Double.isNaN(runningAverage.getAverage()));
assertTrue(Double.isNaN(runningAverage.getStandardDeviation()));
runningAverage.addDatum(1.0);
assertEquals(1.0, runningAverage.getAverage(), EPSILON);
assertTrue(Double.isNaN(runningAverage.getStandardDeviation()));
runningAverage.addDatum(1.0, 2.0);
assertEquals(1.0, runningAverage.getAverage(), EPSILON);
assertEquals(0.0, runningAverage.getStandardDeviation(), EPSILON);
runningAverage.addDatum(8.0, 0.5);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
assertEquals(Math.sqrt(10.5), runningAverage.getStandardDeviation(), EPSILON);
runningAverage.addDatum(-4.0);
assertEquals(2.0/3.0, runningAverage.getAverage(), EPSILON);
assertEquals(Math.sqrt(15.75), runningAverage.getStandardDeviation(), EPSILON);
runningAverage.removeDatum(-4.0);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
assertEquals(Math.sqrt(10.5), runningAverage.getStandardDeviation(), EPSILON);
runningAverage.removeDatum(2.0, 2.0);
assertEquals(2.0, runningAverage.getAverage(), EPSILON);
assertEquals(Math.sqrt(31.5), runningAverage.getStandardDeviation(), EPSILON);
}
}