/// <summary>
/// Calculates the Levenshtein minimum edit distance from one string to another -> optionally uses a MemoryStructure for the algo of your choice
/// </summary>
/// <param name="s"></param>
/// <param name="t"></param>
/// <param name="substitutionCost">int the cost of substituting one letter for another. Typically 1 or 2</param>
/// <param name="d"></param>
/// <returns></returns>
public static int CalculateDistance(string s, string t, int substitutionCost, MemoryStructure d)
{
//guard against nulls and empties
if (string.IsNullOrEmpty(s))
{
if (string.IsNullOrEmpty(t))
return 0;
return t.Length;
}
if (string.IsNullOrEmpty(t))
{
if (string.IsNullOrEmpty(s))
return 0;
return s.Length;
}
var m = s.Length + 1;
var n = t.Length + 1;
// map empties to each other
for (int i = 0; i < m; i++)
{
d[i, 0] = i;
}
for (int i = 0; i < n; i++)
{
d[0, i] = i;
}
for (int i = 1; i < m; i++)
{
for (int j = 1; j < n; j++)
{
if (s[i - 1] == t[j - 1])
{
d[i, j] = d[i - 1, j - 1]; //no cost, letters the same
}
else
{
var delete = d[i - 1, j] + 1;
var insert = d[i, j - 1] + 1;
var substitution = d[i - 1, j - 1] + substitutionCost;
d[i, j] = Math.Min(delete, Math.Min(insert, substitution));
}
}
}
return d[m - 1, n - 1];
}
/// <summary>
/// Calculates the Levenshtein minimum edit distance from one string to another -> optionally uses a MemoryStructure for the algo of your choice
/// </summary>
/// <param name="s"></param>
/// <param name="t"></param>
/// <param name="substitutionCost">int the cost of substituting one letter for another. Typically 1 or 2</param>
/// <param name="d"></param>
/// <returns></returns>
public static int CalculateDistance(string s, string t, int substitutionCost, MemoryStructure d)
{
//guard against nulls and empties
if (string.IsNullOrEmpty(s))
{
if (string.IsNullOrEmpty(t))
{
return(0);
}
return(t.Length);
}
if (string.IsNullOrEmpty(t))
{
if (string.IsNullOrEmpty(s))
{
return(0);
}
return(s.Length);
}
var m = s.Length + 1;
var n = t.Length + 1;
// map empties to each other
for (int i = 0; i < m; i++)
{
d[i, 0] = i;
}
for (int i = 0; i < n; i++)
{
d[0, i] = i;
}
for (int i = 1; i < m; i++)
{
for (int j = 1; j < n; j++)
{
if (s[i - 1] == t[j - 1])
{
d[i, j] = d[i - 1, j - 1]; //no cost, letters the same
}
else
{
var delete = d[i - 1, j] + 1;
var insert = d[i, j - 1] + 1;
var substitution = d[i - 1, j - 1] + substitutionCost;
d[i, j] = Math.Min(delete, Math.Min(insert, substitution));
}
}
}
return(d[m - 1, n - 1]);
}
