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levenshtein.bas
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levenshtein.bas
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Attribute VB_Name = "Module1"
Function Levenshtein(ByVal string1 As String, ByVal string2 As String) As Long
Dim i As Long, j As Long, bs1() As Byte, bs2() As Byte
Dim string1_length As Long
Dim string2_length As Long
Dim distance() As Long
Dim min1 As Long, min2 As Long, min3 As Long
string1_length = Len(string1)
string2_length = Len(string2)
ReDim distance(string1_length, string2_length)
bs1 = string1
bs2 = string2
For i = 0 To string1_length
distance(i, 0) = i
Next
For j = 0 To string2_length
distance(0, j) = j
Next
For i = 1 To string1_length
For j = 1 To string2_length
'slow way: If Mid$(string1, i, 1) = Mid$(string2, j, 1) Then
If bs1((i - 1) * 2) = bs2((j - 1) * 2) Then ' *2 because Unicode every 2nd byte is 0
distance(i, j) = distance(i - 1, j - 1)
Else
'distance(i, j) = Application.WorksheetFunction.Min _
(distance(i - 1, j) + 1, _
distance(i, j - 1) + 1, _
distance(i - 1, j - 1) + 1)
' spell it out, 50 times faster than worksheetfunction.min
min1 = distance(i - 1, j) + 1
min2 = distance(i, j - 1) + 1
min3 = distance(i - 1, j - 1) + 1
If min1 <= min2 And min1 <= min3 Then
distance(i, j) = min1
ElseIf min2 <= min1 And min2 <= min3 Then
distance(i, j) = min2
Else
distance(i, j) = min3
End If
End If
Next
Next
Levenshtein = distance(string1_length, string2_length)
End Function
Function LevenshteinVLookup(searchValue As String, searchRange As Range, colIndex As Integer, Optional maxDist As Integer = 2) As Variant
Dim i As Long, minDist As Integer, curDist As Integer
Dim matchRow As Long, matchFound As Boolean
matchFound = False
minDist = maxDist + 1
For i = 1 To searchRange.Rows.Count
curDist = Levenshtein(searchValue, searchRange.Cells(i, 1).Value)
If curDist <= maxDist And curDist < minDist Then
minDist = curDist
matchRow = i
matchFound = True
End If
Next i
If matchFound Then
LevenshteinVLookup = searchRange.Cells(matchRow, colIndex).Value
Else
LevenshteinVLookup = CVErr(xlErrNA)
End If
End Function