/// <summary>
/// Calculate how well the given words match the string.
/// Uses case insensitive matching.
/// Specify custom costs for the operations.
/// </summary>
public static StrMatch WordMatch(string text, string[] words, int cReplace, int cInsert, int cDelete)
{
if (text == null || words == null || words.Length == 0)
{
throw new ArgumentException("Arguments cannot be null or empty");
}
string pattern = string.Join("", words);
// Find word borders
var slack = new HashSet <int>();
var index = 0;
foreach (var word in words)
{
index += word.Length;
slack.Add(index);
}
// Start node tracker
var startNode = new int[pattern.Length + 1, text.Length + 1];
for (int y = 0; y < startNode.GetLength(1); y++)
{
startNode[0, y] = y;
}
// Calculate custom edit distance
var matrix = new int[pattern.Length + 1, text.Length + 1];
for (int x = 0; x < matrix.GetLength(0); x++)
{
matrix[x, 0] = x * cDelete;
}
for (int y = 1; y < matrix.GetLength(1); y++)
{
matrix[0, y] = 0;
}
for (int y = 1; y <= text.Length; y++)
{
for (int x = 1; x <= pattern.Length; x++)
{
bool isMatch = char.ToLower(pattern[x - 1]) == char.ToLower(text[y - 1]);
int replace = matrix[x - 1, y - 1] + (isMatch ? 0 : cReplace);
int insert = matrix[x, y - 1] + (slack.Contains(x) ? 0 : cInsert);
int delete = matrix[x - 1, y] + cDelete;
if (replace <= insert && replace <= delete)
{
matrix[x, y] = replace;
startNode[x, y] = startNode[x - 1, y - 1];
}
else if (insert <= delete)
{
matrix[x, y] = insert;
startNode[x, y] = startNode[x, y - 1];
}
else
{
matrix[x, y] = delete;
startNode[x, y] = startNode[x - 1, y];
}
}
}
// Find best match distance and end position
int best = matrix[pattern.Length, 0];
int end = 0;
for (int i = 1; i <= text.Length; i++)
{
int value = matrix[pattern.Length, i];
if (value < best)
{
best = value;
end = i;
}
}
// Match failed
if (best == pattern.Length)
{
return(StrMatch.Fail());
}
// Final values
int start = startNode[pattern.Length, end];
int matchLength = end - start;
int middleInserts = matchLength - pattern.Length;
int startInserts = end - pattern.Length - middleInserts;
int distance = best * 100 + startInserts + middleInserts;
return(new StrMatch(text.Substring(start, matchLength), distance, start, matchLength, text.Length, 1 - best / (double)pattern.Length));
}
/// <summary>Find the best matching substring from a string. Substring version of Edit Distance.
/// Specify custom costs for the operations.</summary>
public static StrMatch Find(string text, string pattern, int cReplace, int cInsert, int cDelete)
{
if (text == null || pattern == null)
{
throw new ArgumentException("Strings can't be null");
}
int[,] matrix = new int[pattern.Length + 1, text.Length + 1];
for (int i = 0; i <= pattern.Length; i++)
{
matrix[i, 0] = i * cDelete;
}
for (int i = 1; i <= text.Length; i++)
{
matrix[0, i] = 0;
}
for (int y = 1; y <= text.Length; y++)
{
for (int x = 1; x <= pattern.Length; x++)
{
bool isMatch = pattern[x - 1] == text[y - 1];
var replace = matrix[x - 1, y - 1] + (isMatch ? 0 : cReplace);
var insert = matrix[x, y - 1] + cInsert;
var delete = matrix[x - 1, y] + cDelete;
matrix[x, y] = Math.Min(Math.Min(insert, delete), replace);
}
}
var best = matrix[pattern.Length, 0];
var start = 0;
var end = 0;
for (int i = 1; i <= text.Length; i++)
{
var value = matrix[pattern.Length, i];
if (value < best)
{
best = value;
end = i;
}
}
if (best == pattern.Length)
{
return(StrMatch.Fail());
}
int X = pattern.Length;
int Y = end;
while (X != 0)
{
var left = matrix[X - 1, Y];
var corner = matrix[X - 1, Y - 1];
var up = matrix[X, Y - 1];
if (left <= corner && left <= up)
{
X--;
}
else if (corner <= up)
{
X--;
Y--;
}
else
{
Y--;
}
start = Y;
}
start -= 1;
end -= 1;
var length = end - start + 1;
return(new StrMatch(text.Substring(start, length), best, start, length, text.Length, 1 - best / (double)pattern.Length));
}
