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copied!<pre class="lang-cs prettyprint-override"><code>public static class JaroWinklerDistance { /* The Winkler modification will not be applied unless the * percent match was at or above the mWeightThreshold percent * without the modification. * Winkler's paper used a default value of 0.7 */ private static readonly double mWeightThreshold = 0.7; /* Size of the prefix to be concidered by the Winkler modification. * Winkler's paper used a default value of 4 */ private static readonly int mNumChars = 4; /// <summary> /// Returns the Jaro-Winkler distance between the specified /// strings. The distance is symmetric and will fall in the /// range 0 (perfect match) to 1 (no match). /// </summary> /// <param name="aString1">First String</param> /// <param name="aString2">Second String</param> /// <returns></returns> public static double distance(string aString1, string aString2) { return 1.0 - proximity(aString1,aString2); } /// <summary> /// Returns the Jaro-Winkler distance between the specified /// strings. The distance is symmetric and will fall in the /// range 0 (no match) to 1 (perfect match). /// </summary> /// <param name="aString1">First String</param> /// <param name="aString2">Second String</param> /// <returns></returns> public static double proximity(string aString1, string aString2) { int lLen1 = aString1.Length; int lLen2 = aString2.Length; if (lLen1 == 0) return lLen2 == 0 ? 1.0 : 0.0; int lSearchRange = Math.Max(0,Math.Max(lLen1,lLen2)/2 - 1); // default initialized to false bool[] lMatched1 = new bool[lLen1]; bool[] lMatched2 = new bool[lLen2]; int lNumCommon = 0; for (int i = 0; i < lLen1; ++i) { int lStart = Math.Max(0,i-lSearchRange); int lEnd = Math.Min(i+lSearchRange+1,lLen2); for (int j = lStart; j < lEnd; ++j) { if (lMatched2[j]) continue; if (aString1[i] != aString2[j]) continue; lMatched1[i] = true; lMatched2[j] = true; ++lNumCommon; break; } } if (lNumCommon == 0) return 0.0; int lNumHalfTransposed = 0; int k = 0; for (int i = 0; i < lLen1; ++i) { if (!lMatched1[i]) continue; while (!lMatched2[k]) ++k; if (aString1[i] != aString2[k]) ++lNumHalfTransposed; ++k; } // System.Diagnostics.Debug.WriteLine("numHalfTransposed=" + numHalfTransposed); int lNumTransposed = lNumHalfTransposed/2; // System.Diagnostics.Debug.WriteLine("numCommon=" + numCommon + " numTransposed=" + numTransposed); double lNumCommonD = lNumCommon; double lWeight = (lNumCommonD/lLen1 + lNumCommonD/lLen2 + (lNumCommon - lNumTransposed)/lNumCommonD)/3.0; if (lWeight <= mWeightThreshold) return lWeight; int lMax = Math.Min(mNumChars,Math.Min(aString1.Length,aString2.Length)); int lPos = 0; while (lPos < lMax && aString1[lPos] == aString2[lPos]) ++lPos; if (lPos == 0) return lWeight; return lWeight + 0.1 * lPos * (1.0 - lWeight); } } </code></pre>

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