/*
* 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.math;
import org.apache.mahout.math.function.Functions;
import org.apache.mahout.math.random.MultiNormal;
import org.junit.Test;
public class CentroidTest extends AbstractVectorTest<Centroid> {
@Test
public void testUpdate() {
MultiNormal f = new MultiNormal(20);
Vector a = f.sample();
Vector b = f.sample();
Vector c = f.sample();
DenseVector x = new DenseVector(a);
Centroid x1 = new Centroid(1, x);
x1.update(new Centroid(2, new DenseVector(b)));
Centroid x2 = new Centroid(x1);
x1.update(c);
// check for correct value
Vector mean = a.plus(b).plus(c).assign(Functions.div(3));
assertEquals(0, x1.getVector().minus(mean).norm(1), 1.0e-8);
assertEquals(3, x1.getWeight(), 0);
assertEquals(0, x2.minus(a.plus(b).divide(2)).norm(1), 1.0e-8);
assertEquals(2, x2.getWeight(), 0);
assertEquals(0, new Centroid(x1.getIndex(), x1, x1.getWeight()).minus(x1).norm(1), 1.0e-8);
// and verify shared storage
assertEquals(0, x.minus(x1).norm(1), 0);
assertEquals(3, x1.getWeight(), 1.0e-8);
assertEquals(1, x1.getIndex());
}
@Override
public Centroid vectorToTest(int size) {
return new Centroid(new WeightedVector(new DenseVector(size), 3.15, 51));
}
@Override
public void testSize() {
assertEquals("size", 3, getTestVector().getNumNonZeroElements());
}
@Override
Vector generateTestVector(int cardinality) {
return new Centroid(new WeightedVector(new DenseVector(cardinality), 3.14, 53));
}
}