001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.text.similarity; 018 019import java.util.Arrays; 020 021import org.apache.commons.lang3.StringUtils; 022 023/** 024 * A similarity algorithm indicating the percentage of matched characters between two character sequences. 025 * 026 * <p> 027 * The Jaro measure is the weighted sum of percentage of matched characters 028 * from each file and transposed characters. Winkler increased this measure 029 * for matching initial characters. 030 * </p> 031 * 032 * <p> 033 * This implementation is based on the Jaro Winkler similarity algorithm 034 * from <a href="http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance"> 035 * http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance</a>. 036 * </p> 037 * 038 * <p> 039 * This code has been adapted from Apache Commons Lang 3.3. 040 * </p> 041 * 042 * @since 1.7 043 */ 044public class JaroWinklerSimilarity implements SimilarityScore<Double> { 045 046 /** 047 * Computes the Jaro Winkler Similarity between two character sequences. 048 * 049 * <pre> 050 * sim.apply(null, null) = IllegalArgumentException 051 * sim.apply("foo", null) = IllegalArgumentException 052 * sim.apply(null, "foo") = IllegalArgumentException 053 * sim.apply("", "") = 1.0 054 * sim.apply("foo", "foo") = 1.0 055 * sim.apply("foo", "foo ") = 0.94 056 * sim.apply("foo", "foo ") = 0.91 057 * sim.apply("foo", " foo ") = 0.87 058 * sim.apply("foo", " foo") = 0.51 059 * sim.apply("", "a") = 0.0 060 * sim.apply("aaapppp", "") = 0.0 061 * sim.apply("frog", "fog") = 0.93 062 * sim.apply("fly", "ant") = 0.0 063 * sim.apply("elephant", "hippo") = 0.44 064 * sim.apply("hippo", "elephant") = 0.44 065 * sim.apply("hippo", "zzzzzzzz") = 0.0 066 * sim.apply("hello", "hallo") = 0.88 067 * sim.apply("ABC Corporation", "ABC Corp") = 0.91 068 * sim.apply("D N H Enterprises Inc", "D & H Enterprises, Inc.") = 0.95 069 * sim.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.92 070 * sim.apply("PENNSYLVANIA", "PENNCISYLVNIA") = 0.88 071 * </pre> 072 * 073 * @param left the first CharSequence, must not be null 074 * @param right the second CharSequence, must not be null 075 * @return result similarity 076 * @throws IllegalArgumentException if either CharSequence input is {@code null} 077 */ 078 @Override 079 public Double apply(final CharSequence left, final CharSequence right) { 080 final double defaultScalingFactor = 0.1; 081 082 if (left == null || right == null) { 083 throw new IllegalArgumentException("CharSequences must not be null"); 084 } 085 086 if (StringUtils.equals(left, right)) { 087 return 1d; 088 } 089 090 final int[] mtp = matches(left, right); 091 final double m = mtp[0]; 092 if (m == 0) { 093 return 0d; 094 } 095 final double j = ((m / left.length() + m / right.length() + (m - (double) mtp[1] / 2) / m)) / 3; 096 final double jw = j < 0.7d ? j : j + defaultScalingFactor * mtp[2] * (1d - j); 097 return jw; 098 } 099 100 /** 101 * This method returns the Jaro-Winkler string matches, half transpositions, prefix array. 102 * 103 * @param first the first string to be matched 104 * @param second the second string to be matched 105 * @return mtp array containing: matches, half transpositions, and prefix 106 */ 107 protected static int[] matches(final CharSequence first, final CharSequence second) { 108 CharSequence max, min; 109 if (first.length() > second.length()) { 110 max = first; 111 min = second; 112 } else { 113 max = second; 114 min = first; 115 } 116 final int range = Math.max(max.length() / 2 - 1, 0); 117 final int[] matchIndexes = new int[min.length()]; 118 Arrays.fill(matchIndexes, -1); 119 final boolean[] matchFlags = new boolean[max.length()]; 120 int matches = 0; 121 for (int mi = 0; mi < min.length(); mi++) { 122 final char c1 = min.charAt(mi); 123 for (int xi = Math.max(mi - range, 0), xn = Math.min(mi + range + 1, max.length()); xi < xn; xi++) { 124 if (!matchFlags[xi] && c1 == max.charAt(xi)) { 125 matchIndexes[mi] = xi; 126 matchFlags[xi] = true; 127 matches++; 128 break; 129 } 130 } 131 } 132 final char[] ms1 = new char[matches]; 133 final char[] ms2 = new char[matches]; 134 for (int i = 0, si = 0; i < min.length(); i++) { 135 if (matchIndexes[i] != -1) { 136 ms1[si] = min.charAt(i); 137 si++; 138 } 139 } 140 for (int i = 0, si = 0; i < max.length(); i++) { 141 if (matchFlags[i]) { 142 ms2[si] = max.charAt(i); 143 si++; 144 } 145 } 146 int halfTranspositions = 0; 147 for (int mi = 0; mi < ms1.length; mi++) { 148 if (ms1[mi] != ms2[mi]) { 149 halfTranspositions++; 150 } 151 } 152 int prefix = 0; 153 for (int mi = 0; mi < Math.min(4, min.length()); mi++) { 154 if (first.charAt(mi) == second.charAt(mi)) { 155 prefix++; 156 } else { 157 break; 158 } 159 } 160 return new int[] {matches, halfTranspositions, prefix}; 161 } 162 163}