java Levenshtein距离

Posted 2021-05-08

def levenshteinDistance(str1, str2):
    m = len(str1)
    n = len(str2)
    lensum = float(m + n)
    d = []           
    for i in range(m+1):
        d.append([i])        
    del d[0][0]    
    for j in range(n+1):
        d[0].append(j)       
    for j in range(1,n+1):
        for i in range(1,m+1):
            if str1[i-1] == str2[j-1]:
                d[i].insert(j,d[i-1][j-1])           
            else:
                minimum = min(d[i-1][j]+1, d[i][j-1]+1, d[i-1][j-1]+2)         
                d[i].insert(j, minimum)
    ldist = d[-1][-1]
    ratio = (lensum - ldist)/lensum
    return {'distance':ldist, 'ratio':ratio}
 
print(levenshteinDistance("kitten","sitting"))   
print(levenshteinDistance("rosettacode","raisethysword"))

function levenshtein(str1, str2) {
    var m = str1.length,
        n = str2.length,
        d = [],
        i, j;
 
    if (!m) return n;
    if (!n) return m;
 
    for (i = 0; i <= m; i++) d[i] = [i];
    for (j = 0; j <= n; j++) d[0][j] = j;
 
    for (j = 1; j <= n; j++) {
        for (i = 1; i <= m; i++) {
            if (str1[i-1] == str2[j-1]) d[i][j] = d[i - 1][j - 1];
            else d[i][j] = Math.min(d[i-1][j], d[i][j-1], d[i-1][j-1]) + 1;
        }
    }
    return d[m][n];
}
 
console.log(levenshtein("kitten", "sitting"));
console.log(levenshtein("stop", "tops"));
console.log(levenshtein("rosettacode", "raisethysword"));

public class Levenshtein {
 
    public static int distance(String a, String b) {
        a = a.toLowerCase();
        b = b.toLowerCase();
        // i == 0
        int [] costs = new int [b.length() + 1];
        for (int j = 0; j < costs.length; j++)
            costs[j] = j;
        for (int i = 1; i <= a.length(); i++) {
            // j == 0; nw = lev(i - 1, j)
            costs[0] = i;
            int nw = i - 1;
            for (int j = 1; j <= b.length(); j++) {
                int cj = Math.min(1 + Math.min(costs[j], costs[j - 1]), a.charAt(i - 1) == b.charAt(j - 1) ? nw : nw + 1);
                nw = costs[j];
                costs[j] = cj;
            }
        }
        return costs[b.length()];
    }
 
    public static void main(String [] args) {
        String [] data = { "kitten", "sitting", "saturday", "sunday", "rosettacode", "raisethysword" };
        for (int i = 0; i < data.length; i += 2)
            System.out.println("distance(" + data[i] + ", " + data[i+1] + ") = " + distance(data[i], data[i+1]));
    }
}