    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
    021/**
    022 * Measures the Jaro-Winkler distance of two character sequences.
    023 * It is the complementary of Jaro-Winkler similarity.
    024 *
    025 * @since 1.0
    026 */
    027public class JaroWinklerDistance implements EditDistance<Double> {
    028
    029    /**
    030     * @deprecated Deprecated as of 1.7. This constant will be removed in 2.0.
    031     */
    032    @Deprecated
    033    public static final int INDEX_NOT_FOUND = -1;
    034
    035    /**
    036     * Computes the Jaro Winkler Distance between two character sequences.
    037     *
    038     * <pre>
    039     * distance.apply(null, null)          = IllegalArgumentException
    040     * distance.apply("foo", null)         = IllegalArgumentException
    041     * distance.apply(null, "foo")         = IllegalArgumentException
    042     * distance.apply("", "")              = 0.0
    043     * distance.apply("foo", "foo")        = 0.0
    044     * distance.apply("foo", "foo ")       = 0.06
    045     * distance.apply("foo", "foo  ")      = 0.09
    046     * distance.apply("foo", " foo ")      = 0.13
    047     * distance.apply("foo", "  foo")      = 0.49
    048     * distance.apply("", "a")             = 1.0
    049     * distance.apply("aaapppp", "")       = 1.0
    050     * distance.apply("frog", "fog")       = 0.07
    051     * distance.apply("fly", "ant")        = 1.0
    052     * distance.apply("elephant", "hippo") = 0.56
    053     * distance.apply("hippo", "elephant") = 0.56
    054     * distance.apply("hippo", "zzzzzzzz") = 1.0
    055     * distance.apply("hello", "hallo")    = 0.12
    056     * distance.apply("ABC Corporation", "ABC Corp") = 0.09
    057     * distance.apply("D N H Enterprises Inc", "D &amp; H Enterprises, Inc.") = 0.05
    058     * distance.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.08
    059     * distance.apply("PENNSYLVANIA", "PENNCISYLVNIA") = 0.12
    060     * </pre>
    061     *
    062     * @param left the first CharSequence, must not be null
    063     * @param right the second CharSequence, must not be null
    064     * @return result distance
    065     * @throws IllegalArgumentException if either CharSequence input is {@code null}
    066     */
    067    @Override
    068    public Double apply(final CharSequence left, final CharSequence right) {
    069
    070        if (left == null || right == null) {
    071            throw new IllegalArgumentException("CharSequences must not be null");
    072        }
    073
    074        // TODO: replace the rest of the code by this in 2.0, see TEXT-104
    075        //
    076        // JaroWinklerSimilarity similarity = new JaroWinklerSimilarity();
    077        // return 1 - similarity.apply(left, right);
    078
    079        final double defaultScalingFactor = 0.1;
    080        final int[] mtp = matches(left, right);
    081        final double m = mtp[0];
    082        if (m == 0) {
    083            return 0D;
    084        }
    085        final double j = ((m / left.length() + m / right.length() + (m - (double) mtp[1] / 2) / m)) / 3;
    086        final double jw = j < 0.7D ? j : j + defaultScalingFactor * mtp[2] * (1D - j);
    087        return jw;
    088    }
    089
    090    // TODO: remove this method in 2.0, see TEXT-104
    091    /**
    092     * This method returns the Jaro-Winkler string matches, half transpositions, prefix array.
    093     *
    094     * @param first the first string to be matched
    095     * @param second the second string to be matched
    096     * @return mtp array containing: matches, half transpositions, and prefix
    097     * @deprecated Deprecated as of 1.7. This method will be removed in 2.0, and moved to a Jaro Winkler similarity
    098     *             class.
    099     */
    100    @Deprecated
    101    protected static int[] matches(final CharSequence first, final CharSequence second) {
    102        CharSequence max, min;
    103        if (first.length() > second.length()) {
    104            max = first;
    105            min = second;
    106        } else {
    107            max = second;
    108            min = first;
    109        }
    110        final int range = Math.max(max.length() / 2 - 1, 0);
    111        final int[] matchIndexes = new int[min.length()];
    112        Arrays.fill(matchIndexes, -1);
    113        final boolean[] matchFlags = new boolean[max.length()];
    114        int matches = 0;
    115        for (int mi = 0; mi < min.length(); mi++) {
    116            final char c1 = min.charAt(mi);
    117            for (int xi = Math.max(mi - range, 0), xn = Math.min(mi + range + 1, max.length()); xi < xn; xi++) {
    118                if (!matchFlags[xi] && c1 == max.charAt(xi)) {
    119                    matchIndexes[mi] = xi;
    120                    matchFlags[xi] = true;
    121                    matches++;
    122                    break;
    123                }
    124            }
    125        }
    126        final char[] ms1 = new char[matches];
    127        final char[] ms2 = new char[matches];
    128        for (int i = 0, si = 0; i < min.length(); i++) {
    129            if (matchIndexes[i] != -1) {
    130                ms1[si] = min.charAt(i);
    131                si++;
    132            }
    133        }
    134        for (int i = 0, si = 0; i < max.length(); i++) {
    135            if (matchFlags[i]) {
    136                ms2[si] = max.charAt(i);
    137                si++;
    138            }
    139        }
    140        int halfTranspositions = 0;
    141        for (int mi = 0; mi < ms1.length; mi++) {
    142            if (ms1[mi] != ms2[mi]) {
    143                halfTranspositions++;
    144            }
    145        }
    146        int prefix = 0;
    147        for (int mi = 0; mi < Math.min(4, min.length()); mi++) {
    148            if (first.charAt(mi) == second.charAt(mi)) {
    149                prefix++;
    150            } else {
    151                break;
    152            }
    153        }
    154        return new int[] {matches, halfTranspositions, prefix};
    155    }
    156}