Skip to content

Instantly share code, notes, and snippets.

@tonyjoanes
Created November 26, 2015 09:37
Show Gist options
  • Save tonyjoanes/3aa4b4299913d23cab0f to your computer and use it in GitHub Desktop.
Save tonyjoanes/3aa4b4299913d23cab0f to your computer and use it in GitHub Desktop.
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
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];
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment