Created
November 26, 2015 09:37
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A couple of Levenshtein Calculations implementations. Useful for finding the distance between two strings. The distance is how many edits are required to make the strings the same
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public static int Compute(string s, string t) | |
{ | |
int n = s.Length; | |
int m = t.Length; | |
int[,] d = new int[n + 1, m + 1]; | |
// Step 1 | |
if (n == 0) | |
{ | |
return m; | |
} | |
if (m == 0) | |
{ | |
return n; | |
} | |
// Step 2 | |
for (int i = 0; i <= n; d[i, 0] = i++) | |
{ | |
} | |
for (int j = 0; j <= m; d[0, j] = j++) | |
{ | |
} | |
// Step 3 | |
for (int i = 1; i <= n; i++) | |
{ | |
//Step 4 | |
for (int j = 1; j <= m; j++) | |
{ | |
// Step 5 | |
int cost = (t[j - 1] == s[i - 1]) ? 0 : 1; | |
// Step 6 | |
d[i, j] = Math.Min(Math.Min(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 CalcLevenshteinDistance(string a, string b) | |
{ | |
if (String.IsNullOrEmpty(a) || String.IsNullOrEmpty(b)) return 0; | |
int lengthA = a.Length; | |
int lengthB = b.Length; | |
var distances = new int[lengthA + 1, lengthB + 1]; | |
for (int i = 0; i <= lengthA; distances[i, 0] = i++) ; | |
for (int j = 0; j <= lengthB; distances[0, j] = j++) ; | |
for (int i = 1; i <= lengthA; i++) | |
for (int j = 1; j <= lengthB; j++) | |
{ | |
int cost = b[j - 1] == a[i - 1] ? 0 : 1; | |
distances[i, j] = Math.Min | |
( | |
Math.Min(distances[i - 1, j] + 1, distances[i, j - 1] + 1), | |
distances[i - 1, j - 1] + cost | |
); | |
} | |
return distances[lengthA, lengthB]; | |
} |
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