/// <summary>
/// Longest Common Subsequence. A good value is greater than 0.33.
/// </summary>
/// <param name="input"></param>
/// <param name="comparedTo"></param>
/// <param name="caseSensitive"></param>
/// <returns>Returns a Tuple of the sub sequence string and the match coefficient.</returns>
public static Tuple <string, double> LongestCommonSubsequence(this string input, string comparedTo, bool caseSensitive = false)
{
if (string.IsNullOrWhiteSpace(input) || string.IsNullOrWhiteSpace(comparedTo))
{
return(new Tuple <string, double>(string.Empty, 0.0d));
}
if (!caseSensitive)
{
input = input.ToLower();
comparedTo = comparedTo.ToLower();
}
int inputLen = input.Length;
int comparedToLen = comparedTo.Length;
int[,] lcs = new int[inputLen + 1, comparedToLen + 1];
LcsDirection[,] tracks = new LcsDirection[inputLen + 1, comparedToLen + 1];
int[,] w = new int[inputLen + 1, comparedToLen + 1];
int i, j;
for (i = 0; i <= inputLen; ++i)
{
lcs[i, 0] = 0;
tracks[i, 0] = LcsDirection.North;
}
for (j = 0; j <= comparedToLen; ++j)
{
lcs[0, j] = 0;
tracks[0, j] = LcsDirection.West;
}
for (i = 1; i <= inputLen; ++i)
{
for (j = 1; j <= comparedToLen; ++j)
{
if (input[i - 1].Equals(comparedTo[j - 1]))
{
int k = w[i - 1, j - 1];
//lcs[i,j] = lcs[i-1,j-1] + 1;
lcs[i, j] = lcs[i - 1, j - 1] + Square(k + 1) - Square(k);
tracks[i, j] = LcsDirection.NorthWest;
w[i, j] = k + 1;
}
else
{
lcs[i, j] = lcs[i - 1, j - 1];
tracks[i, j] = LcsDirection.None;
}
if (lcs[i - 1, j] >= lcs[i, j])
{
lcs[i, j] = lcs[i - 1, j];
tracks[i, j] = LcsDirection.North;
w[i, j] = 0;
}
if (lcs[i, j - 1] >= lcs[i, j])
{
lcs[i, j] = lcs[i, j - 1];
tracks[i, j] = LcsDirection.West;
w[i, j] = 0;
}
}
}
i = inputLen;
j = comparedToLen;
string subseq = "";
double p = lcs[i, j];
//trace the backtracking matrix.
while (i > 0 || j > 0)
{
if (tracks[i, j] == LcsDirection.NorthWest)
{
i--;
j--;
subseq = input[i] + subseq;
//Trace.WriteLine(i + " " + input1[i] + " " + j);
}
else if (tracks[i, j] == LcsDirection.North)
{
i--;
}
else if (tracks[i, j] == LcsDirection.West)
{
j--;
}
}
double coef = p / (inputLen * comparedToLen);
Tuple <string, double> retval = new Tuple <string, double>(subseq, coef);
return(retval);
}
/// <summary>
/// Longest Common Subsequence. A good value is greater than 0.33.
/// </summary>
/// <param name="input"></param>
/// <param name="comparedTo"></param>
/// <param name="caseSensitive"></param>
/// <returns>Returns a Tuple of the sub sequence string and the match coeficient.</returns>
public static Tuple<string, double> LongestCommonSubsequence(this string input, string comparedTo, bool caseSensitive = false)
{
if (string.IsNullOrWhiteSpace(input) || string.IsNullOrWhiteSpace(comparedTo)) return new Tuple<string, double>(string.Empty, 0.0d);
if (!caseSensitive)
{
input = input.ToLower();
comparedTo = comparedTo.ToLower();
}
int inputLen = input.Length;
int comparedToLen = comparedTo.Length;
int[,] lcs = new int[inputLen + 1, comparedToLen + 1];
LcsDirection[,] tracks = new LcsDirection[inputLen + 1, comparedToLen + 1];
int[,] w = new int[inputLen + 1, comparedToLen + 1];
int i, j;
for (i = 0; i <= inputLen; ++i)
{
lcs[i, 0] = 0;
tracks[i, 0] = LcsDirection.North;
}
for (j = 0; j <= comparedToLen; ++j)
{
lcs[0, j] = 0;
tracks[0, j] = LcsDirection.West;
}
for (i = 1; i <= inputLen; ++i)
{
for (j = 1; j <= comparedToLen; ++j)
{
if (input[i - 1].Equals(comparedTo[j - 1]))
{
int k = w[i - 1, j - 1];
//lcs[i,j] = lcs[i-1,j-1] + 1;
lcs[i, j] = lcs[i - 1, j - 1] + Square(k + 1) - Square(k);
tracks[i, j] = LcsDirection.NorthWest;
w[i, j] = k + 1;
}
else
{
lcs[i, j] = lcs[i - 1, j - 1];
tracks[i, j] = LcsDirection.None;
}
if (lcs[i - 1, j] >= lcs[i, j])
{
lcs[i, j] = lcs[i - 1, j];
tracks[i, j] = LcsDirection.North;
w[i, j] = 0;
}
if (lcs[i, j - 1] >= lcs[i, j])
{
lcs[i, j] = lcs[i, j - 1];
tracks[i, j] = LcsDirection.West;
w[i, j] = 0;
}
}
}
i = inputLen;
j = comparedToLen;
string subseq = "";
double p = lcs[i, j];
//trace the backtracking matrix.
while (i > 0 || j > 0)
{
if (tracks[i, j] == LcsDirection.NorthWest)
{
i--;
j--;
subseq = input[i] + subseq;
//Trace.WriteLine(i + " " + input1[i] + " " + j);
}
else if (tracks[i, j] == LcsDirection.North)
{
i--;
}
else if (tracks[i, j] == LcsDirection.West)
{
j--;
}
}
double coef = p / (inputLen * comparedToLen);
Tuple<string, double> retval = new Tuple<string, double>(subseq, coef);
return retval;
}
/// <summary>
/// Longest Common Subsequence.
/// </summary>
/// <param name="input"></param>
/// <param name="comparedTo"></param>
/// <param name="caseSensitive"></param>
/// <returns>Returns a Tuple of the sub sequence string and the match coefficient.</returns>
public static Tuple<string, double> LongestCommonSubsequence(
this string input,
string comparedTo,
bool caseSensitive = false)
{
if (string.IsNullOrWhiteSpace(input) || string.IsNullOrWhiteSpace(comparedTo))
{
return new Tuple<string, double>(string.Empty, 0.0d);
}
if (!caseSensitive)
{
input = input.ToLower();
comparedTo = comparedTo.ToLower();
}
var inputLen = input.Length;
var comparedToLen = comparedTo.Length;
var lcs = new int[inputLen + 1, comparedToLen + 1];
var tracks = new LcsDirection[inputLen + 1, comparedToLen + 1];
var w = new int[inputLen + 1, comparedToLen + 1];
int i, j;
for (i = 0; i <= inputLen; ++i)
{
lcs[i, 0] = 0;
tracks[i, 0] = LcsDirection.North;
}
for (j = 0; j <= comparedToLen; ++j)
{
lcs[0, j] = 0;
tracks[0, j] = LcsDirection.West;
}
for (i = 1; i <= inputLen; ++i)
{
for (j = 1; j <= comparedToLen; ++j)
{
if (input[i - 1].Equals(comparedTo[j - 1]))
{
var k = w[i - 1, j - 1];
lcs[i, j] = lcs[i - 1, j - 1] + Square(k + 1) - Square(k);
tracks[i, j] = LcsDirection.NorthWest;
w[i, j] = k + 1;
}
else
{
lcs[i, j] = lcs[i - 1, j - 1];
tracks[i, j] = LcsDirection.None;
}
if (lcs[i - 1, j] >= lcs[i, j])
{
lcs[i, j] = lcs[i - 1, j];
tracks[i, j] = LcsDirection.North;
w[i, j] = 0;
}
if (lcs[i, j - 1] >= lcs[i, j])
{
lcs[i, j] = lcs[i, j - 1];
tracks[i, j] = LcsDirection.West;
w[i, j] = 0;
}
}
}
i = inputLen;
j = comparedToLen;
var subseq = string.Empty;
double p = lcs[i, j];
while (i > 0 || j > 0)
{
switch (tracks[i, j])
{
case LcsDirection.NorthWest:
i--;
j--;
subseq = input[i] + subseq;
break;
case LcsDirection.North:
i--;
break;
case LcsDirection.West:
j--;
break;
case LcsDirection.None:
break;
default:
throw new ArgumentOutOfRangeException();
}
}
var coef = p / (inputLen * comparedToLen);
return new Tuple<string, double>(subseq, coef);
}
