/**
* 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.utils;
import org.apache.mahout.matrix.Vector;
/**
* This class implements a "manhattan distance" metric by summing the absolute
* values of the difference between each coordinate, optionally with weights.
*/
public class WeightedManhattanDistanceMeasure extends WeightedDistanceMeasure {
@Override
public double distance(Vector p1, Vector p2) {
double result = 0;
Vector res = p2.minus(p1);
if (weights == null) {
for (int i = 0; i < res.cardinality(); i++) {
result += Math.abs(res.get(i));
}
}
else {
for (int i = 0; i < res.cardinality(); i++) {
result += Math.abs(res.get(i) * weights.get(i)); // todo this is where the weights goes, right?
}
}
return result;
}
}