Java String Levenshtein Distance levenshteinSimilarity(String string1, String string2)

Description

Copyright (c) 2011, Regents of the University of Colorado
All rights reserved.

License

Open Source License

Declaration

public static float levenshteinSimilarity(String string1, String string2) 

Method Source Code

//package com.java2s;

public class Main {
    /**//www  .  java  2s  . co m
     * <br>
     * Copyright (c) 2011, Regents of the University of Colorado <br>
     * All rights reserved.
     *
     * @author Philip Ogren
     * <p/>
     * <p/>
     * Portions of this code were derived from pseudocode located at
     * http://en.wikipedia.org/wiki/Levenshtein_distance
     */

    public static float levenshteinSimilarity(String string1, String string2) {
        if (string1.length() == 0 && string2.length() == 0) {
            return 1.0f;
        }
        int editDistance = editDistance(string1, string2);

        float similarity = (float) editDistance / (string1.length() + string2.length());
        return 1 - Math.min(similarity, 1.0f);
    }

    public static int editDistance(String string1, String string2) {
        int rowCount = string1.length() + 1;
        int columnCount = string2.length() + 1;

        int[][] matrix = new int[rowCount][columnCount];

        for (int rowIndex = 0; rowIndex < rowCount; rowIndex++) {
            matrix[rowIndex][0] = rowIndex;
        }

        for (int columnIndex = 0; columnIndex < columnCount; columnIndex++) {
            matrix[0][columnIndex] = columnIndex;
        }

        for (int rowIndex = 1; rowIndex < matrix.length; rowIndex++) {
            for (int columnIndex = 1; columnIndex < matrix[0].length; columnIndex++) {
                char char1 = string1.charAt(rowIndex - 1);
                char char2 = string2.charAt(columnIndex - 1);
                if (char1 == char2) {
                    matrix[rowIndex][columnIndex] = matrix[rowIndex - 1][columnIndex - 1];
                } else {
                    int left = matrix[rowIndex][columnIndex - 1];
                    int up = matrix[rowIndex - 1][columnIndex];
                    int leftUp = matrix[rowIndex - 1][columnIndex - 1];
                    int distance = Math.min(left, up);
                    distance = Math.min(distance, leftUp);
                    matrix[rowIndex][columnIndex] = distance + 1;
                }
            }
        }

        return matrix[rowCount - 1][columnCount - 1];
    }
}

Related

1. levenshteinDistance(String wordForm, String lemma)
2. levenshteinDistance(String x, String y)
3. levenshteinDistance(String[] a, String[] b)
4. levenshteinDistanceRatio(CharSequence lhs, CharSequence rhs)
5. levenshteinEquals(double threshold, String dom1, String dom2)