org.apache.mahout.common.distance.EuclideanDistanceMeasure Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of mahout-mr Show documentation

Scalable machine learning libraries

There is a newer version: 0.13.0

/**
 * 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.common.distance;

import org.apache.mahout.math.Vector;

/**
 * This class implements a Euclidean distance metric by summing the square root of the squared differences
 * between each coordinate.
 * 
 * If you don't care about the true distance and only need the values for comparison, then the base class,
 * {@link SquaredEuclideanDistanceMeasure}, will be faster since it doesn't do the actual square root of the
 * squared differences.
 */
public class EuclideanDistanceMeasure extends SquaredEuclideanDistanceMeasure {
  
  @Override
  public double distance(Vector v1, Vector v2) {
    return Math.sqrt(super.distance(v1, v2));
  }
  
  @Override
  public double distance(double centroidLengthSquare, Vector centroid, Vector v) {
    return Math.sqrt(super.distance(centroidLengthSquare, centroid, v));
  }
}