/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.transform.normalize;
import org.grouplens.lenskit.vectors.MutableSparseVector;
import org.grouplens.lenskit.vectors.SparseVector;
import org.junit.Test;
import static org.hamcrest.Matchers.closeTo;
import static org.junit.Assert.assertThat;
/**
* @author <a href="http://www.grouplens.org">GroupLens Research</a>
*/
public class MeanCenteringVectorNormalizerTest {
VectorNormalizer norm = new MeanCenteringVectorNormalizer();
@Test
public void testEmptyReference() {
MutableSparseVector msv = MutableSparseVector.create(4L);
msv.set(4, 3.5);
norm.normalize(SparseVector.empty(), msv);
assertThat(msv.get(4), closeTo(3.5, 1.0e-5));
}
@Test
public void testSameReference() {
MutableSparseVector msv = MutableSparseVector.create(4L);
msv.set(4, 3.5);
norm.normalize(msv, msv);
assertThat(msv.get(4), closeTo(0, 1.0e-5));
}
@Test
public void testTransform() {
MutableSparseVector reference = MutableSparseVector.create(4L, 5L);
reference.set(4, 3.5);
reference.set(5, 2.5);
VectorTransformation tx = norm.makeTransformation(reference);
MutableSparseVector msv = reference.mutableCopy();
tx.apply(msv);
assertThat(msv.get(4), closeTo(0.5, 1.0e-5));
assertThat(msv.get(5), closeTo(-0.5, 1.0e-5));
msv.set(4, 2);
tx.unapply(msv);
assertThat(msv.get(4), closeTo(5, 1.0e-5));
}
}