Java tutorial
/** * 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.common.parameters.Parametered; import org.apache.mahout.math.Vector; /** This interface is used for objects which can determine a distance metric between two points */ public interface DistanceMeasure extends Parametered { /** * Returns the distance metric applied to the arguments * * @param v1 * a Vector defining a multidimensional point in some feature space * @param v2 * a Vector defining a multidimensional point in some feature space * @return a scalar doubles of the distance */ double distance(Vector v1, Vector v2); /** * Optimized version of distance metric for sparse vectors. This distance computation requires operations * proportional to the number of non-zero elements in the vector instead of the cardinality of the vector. * * @param centroidLengthSquare * Square of the length of centroid * @param centroid * Centroid vector */ double distance(double centroidLengthSquare, Vector centroid, Vector v); }