/*
* 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.common.RandomUtils;
import org.apache.mahout.math.function.DoubleFunction;
import org.junit.Test;
import java.util.Iterator;
import java.util.Random;
public class PermutedVectorViewTest extends MahoutTestCase {
@Test
public void testViewBasics() {
Vector v = randomVector();
int[] pivot = pivot();
Vector pvv = new PermutedVectorView(v, pivot);
// verify the view has the same contents
for (int i = 0; i < 20; i++) {
assertEquals("Element " + i, v.get(pivot[i]), pvv.get(i), 0);
}
// change a view element or two on each side
pvv.set(6, 321);
v.set(9, 512);
// verify again
for (int i = 0; i < 20; i++) {
assertEquals("Element " + i, v.get(pivot[i]), pvv.get(i), 0);
}
}
@Test
public void testIterators() {
int[] pivot = pivot();
int[] unpivot = unpivot();
Vector v = randomVector();
PermutedVectorView pvv = new PermutedVectorView(v, pivot);
// check a simple operation and thus an iterator
assertEquals(v.zSum(), pvv.zSum(), 0);
assertEquals(v.getNumNondefaultElements(), pvv.getNumNondefaultElements());
v.set(11, 0);
assertEquals(v.getNumNondefaultElements(), pvv.getNumNondefaultElements());
Iterator<Vector.Element> vi = pvv.iterator();
int i = 0;
while (vi.hasNext()) {
Vector.Element e = vi.next();
assertEquals("Index " + i, i, pivot[e.index()]);
assertEquals("Reverse Index " + i, unpivot[i], e.index());
assertEquals("Self-value " + i, e.get(), pvv.get(e.index()), 0);
// note that we iterate in the original vector order
assertEquals("Value " + i, v.get(i), e.get(), 0);
i++;
}
}
private static int[] pivot() {
return new int[]{11, 7, 10, 9, 8, 3, 17, 0, 19, 13, 12, 1, 5, 6, 16, 2, 4, 14, 18, 15};
}
private static int[] unpivot() {
int[] pivot = pivot();
int[] unpivot = new int[20];
for (int i = 0; i < 20; i++) {
unpivot[pivot[i]] = i;
}
return unpivot;
}
private static Vector randomVector() {
Vector v = new DenseVector(20);
v.assign(new DoubleFunction() {
private final Random gen = RandomUtils.getRandom();
@Override
public double apply(double arg1) {
return gen.nextDouble();
}
});
return v;
}
}