Java String Levenshtein Distance levenshteinDistance(String s, String t)

Description

Computes the Levensthein distance between two given strings.

License

Open Source License

Parameter

Parameter	Description
s	- the first string
t	- the second string

Return

the Levensthein distance between s and t

Declaration

public static int levenshteinDistance(String s, String t) 

Method Source Code

//package com.java2s;
/**//from  w  w  w .  j a  v  a2 s .co  m
 * Copyright 2016 
 * Ivan Cantador
 * Information Retrieval Group at Universidad Autonoma de Madrid
 *
 * This is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * This software is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with 
 * the current software. If not, see <http://www.gnu.org/licenses/>.
 */

public class Main {
    /**
     * Computes the Levensthein distance between two given strings.
     *
     * @param s - the first string
     * @param t - the second string
     *
     * @return the Levensthein distance between s and t
     */
    public static int levenshteinDistance(String s, String t) {
        int d[][]; // matrix
        int n; // length of s
        int m; // length of t
        int i; // iterates through s
        int j; // iterates through t
        char s_i; // ith character of s
        char t_j; // jth character of t
        int cost; // cost

        // Step 1    
        n = s.length();
        m = t.length();
        if (n == 0) {
            return m;
        }
        if (m == 0) {
            return n;
        }
        d = new int[n + 1][m + 1];

        // Step 2
        for (i = 0; i <= n; i++) {
            d[i][0] = i;
        }

        for (j = 0; j <= m; j++) {
            d[0][j] = j;
        }

        // Step 3
        for (i = 1; i <= n; i++) {
            s_i = s.charAt(i - 1);

            // Step 4
            for (j = 1; j <= m; j++) {
                t_j = t.charAt(j - 1);

                // Step 5
                if (s_i == t_j) {
                    cost = 0;
                } else {
                    cost = 1;
                }

                // Step 6
                d[i][j] = minimum(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + cost);
            }
        }

        // Step 7
        return d[n][m];
    }

    private static int minimum(int a, int b, int c) {
        int mi;

        mi = a;
        if (b < mi) {
            mi = b;
        }
        if (c < mi) {
            mi = c;
        }

        return mi;
    }
}

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