Here you can find the source of vectorDistance(double[] vec1, double[] vec2, double power)
| Parameter | Description |
|---|---|
| vec1 | The first vector |
| vec2 | The second vector |
| power | The power (2 for cartesian distance, 1 for manhattan, etc.) |
The length. <p/> See http://en.wikipedia.org/wiki/Lp_space
public static double vectorDistance(double[] vec1, double[] vec2, double power)
//package com.java2s; /*/* w w w .j a v a2s . com*/ * 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. */ public class Main { /** * Calculate the p-norm (i.e. length) between two vectors * * @param vec1 The first vector * @param vec2 The second vector * @param power The power (2 for cartesian distance, 1 for manhattan, etc.) * @return The length. * <p/> * See http://en.wikipedia.org/wiki/Lp_space * @see #vectorDistance(double[], double[], double, double) */ public static double vectorDistance(double[] vec1, double[] vec2, double power) { return vectorDistance(vec1, vec2, power, 1.0 / power); } /** * Calculate the p-norm (i.e. length) between two vectors * * @param vec1 The first vector * @param vec2 The second vector * @param power The power (2 for cartesian distance, 1 for manhattan, etc.) * @param oneOverPower If you've precalculated oneOverPower and cached it, use this method to save one division operation over {@link #vectorDistance(double[], double[], double)}. * @return The length. */ public static double vectorDistance(double[] vec1, double[] vec2, double power, double oneOverPower) { double result = 0; if (power == 0) { for (int i = 0; i < vec1.length; i++) { result += vec1[i] - vec2[i] == 0 ? 0 : 1; } } else if (power == 1.0) { for (int i = 0; i < vec1.length; i++) { result += vec1[i] - vec2[i]; } } else if (power == 2.0) { result = Math.sqrt(distSquaredCartesian(vec1, vec2)); } else if (power == Integer.MAX_VALUE || Double.isInfinite(power)) {//infinite norm? for (int i = 0; i < vec1.length; i++) { result = Math.max(result, Math.max(vec1[i], vec2[i])); } } else { for (int i = 0; i < vec1.length; i++) { result += Math.pow(vec1[i] - vec2[i], power); } result = Math.pow(result, oneOverPower); } return result; } /** * The square of the cartesian Distance. Not really a distance, but useful if all that matters is * comparing the result to another one. * * @param vec1 The first point * @param vec2 The second point * @return The squared cartesian distance */ public static double distSquaredCartesian(double[] vec1, double[] vec2) { double result = 0; for (int i = 0; i < vec1.length; i++) { double v = vec1[i] - vec2[i]; result += v * v; } return result; } }