/*
* 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 it.unimi.dsi.fastutil.longs.LongSortedSet;
import org.grouplens.lenskit.collections.LongUtils;
import org.grouplens.lenskit.vectors.MutableSparseVector;
import org.junit.Before;
import org.junit.Test;
import static java.lang.Math.sqrt;
import static org.hamcrest.CoreMatchers.sameInstance;
import static org.hamcrest.Matchers.closeTo;
import static org.hamcrest.Matchers.equalTo;
import static org.junit.Assert.assertThat;
public class UnitVectorNormalizerTest {
UnitVectorNormalizer norm = new UnitVectorNormalizer();
LongSortedSet keySet;
@Before
public void createKeySet() {
keySet = LongUtils.packedSet(1, 3, 4, 6);
}
@Test
public void testScale() {
MutableSparseVector v = MutableSparseVector.create(keySet);
v.set(1, 1);
v.set(4, 1);
assertThat(norm.normalize(v.immutable(), v), sameInstance(v));
assertThat(v.norm(), closeTo(1, 1.0e-6));
assertThat(v.size(), equalTo(2));
assertThat(v.get(1), closeTo(1 / sqrt(2), 1.0e-6));
assertThat(v.get(4), closeTo(1 / sqrt(2), 1.0e-6));
}
@Test
public void testScaleOther() {
MutableSparseVector v = MutableSparseVector.create(keySet);
v.set(1, 1);
v.set(4, 1);
MutableSparseVector ref = MutableSparseVector.create(keySet);
ref.set(1, 1);
ref.set(6, 1);
ref.set(3, 2);
VectorTransformation tx = norm.makeTransformation(ref.immutable());
assertThat(tx.apply(v), sameInstance(v));
assertThat(v.norm(), closeTo(sqrt(2.0 / 6), 1.0e-6));
assertThat(v.size(), equalTo(2));
assertThat(v.get(1), closeTo(1 / sqrt(6), 1.0e-6));
assertThat(v.get(4), closeTo(1 / sqrt(6), 1.0e-6));
assertThat(tx.unapply(v), sameInstance(v));
assertThat(v.size(), equalTo(2));
assertThat(v.get(1), closeTo(1, 1.0e-6));
assertThat(v.get(4), closeTo(1, 1.0e-6));
assertThat(v.sum(), closeTo(2, 1.0e-6));
assertThat(v.norm(), closeTo(sqrt(2), 1.0e-6));
}
}