Find near-duplicates of comma-separated lists using Levenshtein distance [duplicate]

Question

This question already has an answer here:

Potential Duplicates Detection, with 3 Severity Level (1 answer)

Closed 8 years ago.

This question based on the answer of my question yesterday.

To solve my problem, Jean-François Corbett suggested a Levenshtein distance approach. Then I found this code somewhere to get Levenshtein distance percentage.

Public Function GetLevenshteinPercentMatch( _
    ByVal string1 As String, ByVal string2 As String, _
    Optional Normalised As Boolean = False) As Single
Dim iLen As Integer
    If Normalised = False Then
        string1 = UCase$(WorksheetFunction.Trim(string1))
        string2 = UCase$(WorksheetFunction.Trim(string2))
    End If
    iLen = WorksheetFunction.Max(Len(string1), Len(string2))
    GetLevenshteinPercentMatch = (iLen - LevenshteinDistance(string1, string2)) / iLen
End Function

'********************************
'*** Compute Levenshtein Distance
'********************************

Public Function LevenshteinDistance(ByVal s As String, ByVal t As String) As Integer
Dim d() As Integer ' matrix
Dim m As Integer ' length of t
Dim N As Integer ' length of s
Dim i As Integer ' iterates through s
Dim j As Integer ' iterates through t
Dim s_i As String ' ith character of s
Dim t_j As String ' jth character of t
Dim cost As Integer ' cost

  ' Step 1
  N = Len(s)
  m = Len(t)
  If N = 0 Then
    LevenshteinDistance = m
    Exit Function
  End If
  If m = 0 Then
    LevenshteinDistance = N
    Exit Function
  End If
  ReDim d(0 To N, 0 To m) As Integer

  ' Step 2
  For i = 0 To N
    d(i, 0) = i
  Next i

  For j = 0 To m
    d(0, j) = j
  Next j

  ' Step 3

  For i = 1 To N
    s_i = Mid$(s, i, 1)
    ' Step 4
    For j = 1 To m
      t_j = Mid$(t, j, 1)
      ' Step 5
      If s_i = t_j Then
        cost = 0
      Else
        cost = 1
      End If
      ' Step 6
      d(i, j) = WorksheetFunction.Min( _
          d(i - 1, j) + 1, d(i, j - 1) + 1, d(i - 1, j - 1) + cost)

    Next j
  Next i

  ' Step 7
  LevenshteinDistance = d(N, m)

End Function

What I have now is a code that finds exact duplicates in one column,

 Dim duplicate(), i As Long
    Dim delrange As Range, cell As Long
    Dim shtIn As Worksheet, Shtout As Worksheet
    Dim numofrows1
    dim numofrows2
    dim j as long

    Set shtIn = ThisWorkbook.Sheets("process")
    Set Shtout = ThisWorkbook.Sheets("output")

    x = 2
    y = 1

    Set delrange = shtIn.Range("h1:h30000")  'set your range here

    ReDim duplicate(0)
    'search duplicates in 2nd column
    For cell = 1 To delrange.Cells.Count
         If Application.CountIf(delrange, delrange(cell)) > 1 Then
             ReDim Preserve duplicate(i)
             duplicate(i) = delrange(cell).Address
             i = i + 1
         End If
    Next

    'print duplicates
    For i = UBound(duplicate) To LBound(duplicate) Step -1
    Shtout.Cells(x, 1).EntireRow.Value = shtIn.Range(duplicate(i)).EntireRow.Value
    x = x + 1
Next i

numofrows2 = Shtout.Cells(Shtout.Rows.Count, 1).End(xlUp).Row - 1

If Shtout.Cells(2, 1).Value = "" Then
    MsgBox ("No Duplicates Found!")
Else
    MsgBox (numofrows1 & " " & "Potential Duplicates Found")
End If

End Sub

I think that it will be nice if I can combine this two code, but Levenshtein distance is to compare 2 strings. So it can't work together.

I stuck here because I have no idea at all, every reference that I read all tell about comparing two string.

if the parameter this simple : detected as duplicate if the Levenshtein distance percentage is above 90%.

What I must change in this code?

Answer 1

I'm glad my earlier answer was useful to you. You didn't like having to represent each of your possible attributes by one-character symbols...

Ok, as I try to signal to you in the comments there, it is possible to adapt the Levenshtein Distance algorithm to look not at each character in a string, but at each element of an array instead, and do comparisons based on that. In fact it's quite straightforward to make this change:

Before 'Step 1, convert your comma-separated strings into arrays like this:

Dim sSplit() As String
Dim tSplit() As String
sSplit = Split(s, ",")
tSplit = Split(t, ",")

Then replace these four lines of code

N = Len(s)
m = Len(t)
s_i = Mid$(s, i, 1)
t_j = Mid$(t, j, 1)

with these

N = UBound(sSplit) + 1
m = UBound(tSplit) + 1
s_i = sSplit(i - 1)
t_j = tSplit(j - 1)

The + 1 and - 1 are there because Split returns a zero-based array.

Example usage:

?LevenshteinDistance("valros,helmet,42","valros,helmet,42")
 0 
?LevenshteinDistance("valros,helmet,42","knight,helmet")
 2 
?LevenshteinDistance("helmet,iron,knight","plain,helmet")
 3 

Note that 0 means the two strings are identical. You don't need separate code to deal with this.

With the above you should be able to complete your task.

One more note: the Damerau–Levenshtein distance may be a more relevant algorithm for you than the Levenshtein distance. The difference is that in addition to insertion/deletion/substitution, the D-M distance also considers transposition of two adjacent characters. Up to you to decide.

Answer 2

SOLVED!!!

Sub duplicate_separation()
Dim duplicate As Variant, I As Long
Dim vaData As Variant
Dim vadata2 As Variant
Dim delrange As Range, lRow As Long
Dim delrange2 As Range
Dim shtIn As Worksheet, Shtout As Worksheet
Dim numofrows1

Dim j As Long

    Set shtIn = ThisWorkbook.Sheets("process")
    Set Shtout = ThisWorkbook.Sheets("output")


    With shtIn.UsedRange 'set your range here
        Set delrange = shtIn.Range("b1").Resize(.Row + .Rows.Count - 1)


    End With

    vaData = delrange.Value
   ReDim duplicate(1 To 1, 1 To 1)
'search duplicates in 2nd column
    For lRow = 1 To UBound(vaData, 1)
    'choose the parameter
    '1. detect potential duplicate data for similiarity above 70%
   If FuzzyCount(LookupValue:=CStr(vaData(lRow, 1)), TableArray:=delrange, NFPercent:=0.7, Algorithm:=4) > 1 Then

              I = I + 1
            ReDim Preserve duplicate(1 To 1, 1 To I)
            duplicate(1, I) = delrange(lRow).Address
        End If
    Next lRow


        Shtout.Cells(1, 1).Resize(1, 7).Value = _
      Array("Material Number", "Short Description", "Manufacturer", "Material Part Number", "Old Material Number", "Long Description", "sorted ShortDesc")


    If I = 0 Then
        MsgBox ("No Duplicates Found!")
    Else
        'print duplicates
        MsgBox (I & " " & "Potential Duplicates Found")
        Shtout.Cells(2, 1).Resize(I, 6).EntireRow.Value = shtIn.Range(duplicate(1, 1)).Resize(I, 6).EntireRow.Value
    End If




End Sub

Fuzzy v lookup function. by Alan

Private Function NormaliseKey(ByVal String1 As String) As String
NormaliseKey = Replace(UCase$(String1), " ", "")
End Function



Function FuzzyCount(ByVal LookupValue As String, _
                      ByVal TableArray As Range, _
                      Optional NFPercent As Single = 0.05, _
                      Optional Algorithm As Variant = 3) As Long
'**********************************************************************
'** Simple count of (Fuzzy) Matching strings >= NFPercent threshold  **
'**********************************************************************
Dim lMatchCount As Long

Dim rCur As Range

Dim sString1 As String
Dim sString2 As String

'** Normalise lookup value **
sString1 = LCase$(Application.Trim(LookupValue))

For Each rCur In Intersect(TableArray.Resize(, 1), Sheets(TableArray.Parent.Name).UsedRange)

    '** Normalise current Table entry **
    sString2 = LCase$(Application.Trim(CStr(rCur)))

    If sString2 <> "" Then
        If FuzzyPercent(String1:=sString1, _
                        String2:=sString2, _
                        Algorithm:=Algorithm, _
                        Normalised:=False) >= NFPercent Then
            lMatchCount = lMatchCount + 1
        End If
    End If
Next rCur

FuzzyCount = lMatchCount

End Function

Function FuzzyPercent(ByVal String1 As String, _
                      ByVal String2 As String, _
                      Optional Algorithm As Variant = 3, _
                      Optional Normalised As Boolean = False) As Single
'*************************************
'** Return a % match on two strings **
'*************************************
Dim bSoundex As Boolean
Dim bBasicMetaphone As Boolean
Dim intLen1 As Integer, intLen2 As Integer
Dim intCurLen As Integer
Dim intTo As Integer
Dim intPos As Integer
Dim intPtr As Integer
Dim intScore As Integer
Dim intTotScore As Integer
Dim intStartPos As Integer
Dim lngAlgorithm As Long
Dim sngScore As Single
Dim strWork As String

bSoundex = LCase$(CStr(Algorithm)) = "soundex"
bBasicMetaphone = LCase$(CStr(Algorithm)) = "metaphone"

'-------------------------------------------------------
'-- If strings havent been normalised, normalise them --
'-------------------------------------------------------
If Normalised = False Then
    If bSoundex Or bBasicMetaphone Then
       String1 = NormaliseStringAtoZ(String1)
       String2 = NormaliseStringAtoZ(String2)
    Else
        String1 = LCase$(Application.Trim(String1))
        String2 = LCase$(Application.Trim(String2))
    End If
End If

'----------------------------------------------
'-- Give 100% match if strings exactly equal --
'----------------------------------------------
If String1 = String2 Then
    FuzzyPercent = 1
    Exit Function
End If

'If bSoundex Then
'    String1 = Soundex(Replace(String1, " ", ""))
'    String2 = Soundex(Replace(String2, " ", ""))
'    If String1 = String2 Then
'        FuzzyPercent = msngSoundexMatchPercent
'    Else
'        FuzzyPercent = 0
'    End If
'    Exit Function
'ElseIf bBasicMetaphone Then
'    String1 = Metaphone1(String1)
'    String2 = Metaphone1(String2)
'    If String1 = String2 Then
'        FuzzyPercent = msngMetaphoneMatchPercent
'    Else
'        FuzzyPercent = 0
'    End If
'    Exit Function
'End If

intLen1 = Len(String1)
intLen2 = Len(String2)

If intLen1 = 0 Or intLen2 = 0 Then
    FuzzyPercent = 0
    Exit Function
End If

'----------------------------------------
'-- Give 0% match if string length < 2 --
'----------------------------------------
If intLen1 < 2 Then
    FuzzyPercent = 0
    Exit Function
End If

intTotScore = 0                   'initialise total possible score
intScore = 0                      'initialise current score

lngAlgorithm = Val(Algorithm)

'--------------------------------------------------------
'-- If Algorithm = 1 or 3, Search for single characters --
'--------------------------------------------------------
If (lngAlgorithm And 1) <> 0 Then
    If intLen1 < intLen2 Then
        FuzzyAlg1 String1, String2, intScore, intTotScore
    Else
        FuzzyAlg1 String2, String1, intScore, intTotScore
    End If
End If

'-----------------------------------------------------------
'-- If Algorithm = 2 or 3, Search for pairs, triplets etc. --
'-----------------------------------------------------------
If (lngAlgorithm And 2) <> 0 Then
    If intLen1 < intLen2 Then
        FuzzyAlg2 String1, String2, intScore, intTotScore
    Else
        FuzzyAlg2 String2, String1, intScore, intTotScore
    End If
End If

'-------------------------------------------------------------
'-- If Algorithm = 4,5,6,7, use Levenstein Distance method  --
'-- (Algorithm 4 was Dan Ostrander's code)                  --
'-------------------------------------------------------------
If (lngAlgorithm And 4) <> 0 Then
    If intLen1 < intLen2 Then
'        sngScore = FuzzyAlg4(String1, String1)
        sngScore = GetLevenshteinPercentMatch(String1:=String1, _
                                              String2:=String2, _
                                              Normalised:=True)
    Else
'        sngScore = FuzzyAlg4(String2, String1)
        sngScore = GetLevenshteinPercentMatch(String1:=String2, _
                                              String2:=String1, _
                                              Normalised:=True)
    End If
    intScore = intScore + (sngScore * 100)
    intTotScore = intTotScore + 100
End If

FuzzyPercent = intScore / intTotScore

End Function

Private Sub FuzzyAlg1(ByVal String1 As String, _
                      ByVal String2 As String, _
                      ByRef Score As Integer, _
                      ByRef TotScore As Integer)
Dim intLen1 As Integer, intPos As Integer, intPtr As Integer, intStartPos As Integer

intLen1 = Len(String1)
TotScore = TotScore + intLen1              'update total possible score
intPos = 0
For intPtr = 1 To intLen1
    intStartPos = intPos + 1
    intPos = InStr(intStartPos, String2, Mid$(String1, intPtr, 1))
    If intPos > 0 Then
        If intPos > intStartPos + 3 Then     'No match if char is > 3 bytes away
            intPos = intStartPos
        Else
            Score = Score + 1          'Update current score
        End If
    Else
        intPos = intStartPos
    End If
Next intPtr
End Sub
Private Sub FuzzyAlg2(ByVal String1 As String, _
                        ByVal String2 As String, _
                        ByRef Score As Integer, _
                        ByRef TotScore As Integer)
Dim intCurLen As Integer, intLen1 As Integer, intTo As Integer, intPtr As Integer, intPos As Integer
Dim strWork As String

intLen1 = Len(String1)
For intCurLen = 1 To intLen1
    strWork = String2                          'Get a copy of String2
    intTo = intLen1 - intCurLen + 1
    TotScore = TotScore + Int(intLen1 / intCurLen)  'Update total possible score
    For intPtr = 1 To intTo Step intCurLen
        intPos = InStr(strWork, Mid$(String1, intPtr, intCurLen))
        If intPos > 0 Then
            Mid$(strWork, intPos, intCurLen) = String$(intCurLen, &H0) 'corrupt found string
            Score = Score + 1     'Update current score
        End If
    Next intPtr
Next intCurLen

End Sub
'Private Function FuzzyAlg4(strIn1 As String, strIn2 As String) As Single
'
'Dim L1               As Integer
'Dim In1Mask(1 To 24) As Long     'strIn1 is 24 characters max
'Dim iCh              As Integer
'Dim N                As Long
'Dim strTry           As String
'Dim strTest          As String
'
'TopMatch = 0
'L1 = Len(strIn1)
'strTest = UCase(strIn1)
'strCompare = UCase(strIn2)
'For iCh = 1 To L1
'    In1Mask(iCh) = 2 ^ iCh
'Next iCh      'Loop thru all ordered combinations of characters in strIn1
'For N = 2 ^ (L1 + 1) - 1 To 1 Step -1
'    strTry = ""
'    For iCh = 1 To L1
'        If In1Mask(iCh) And N Then
'            strTry = strTry & Mid(strTest, iCh, 1)
'        End If
'    Next iCh
'    If Len(strTry) > TopMatch Then FuzzyAlg4Test strTry
'Next N
'FuzzyAlg4 = TopMatch / CSng(L1)
'End Function
'Sub FuzzyAlg4Test(strIn As String)
'
'Dim l          As Integer
'Dim strTry   As String
'Dim iCh        As Integer
'
'l = Len(strIn)
'If l <= TopMatch Then Exit Sub
'strTry = "*"
'For iCh = 1 To l
'    strTry = strTry & Mid(strIn, iCh, 1) & "*"
'Next iCh
'If strCompare Like strTry Then
'    If l > TopMatch Then TopMatch = l
'End If
'End Sub

Public Function GetLevenshteinPercentMatch(ByVal String1 As String, _
                                            ByVal String2 As String, _
                                            Optional Normalised As Boolean = False) As Single
Dim iLen As Integer
If Normalised = False Then
    String1 = UCase$(WorksheetFunction.Trim(String1))
    String2 = UCase$(WorksheetFunction.Trim(String2))
End If
iLen = WorksheetFunction.Max(Len(String1), Len(String2))
GetLevenshteinPercentMatch = (iLen - LevenshteinDistance(String1, String2)) / iLen
End Function

Private Function NormaliseStringAtoZ(ByVal String1 As String) As String
'---------------------------------------------------------
'-- Remove all but alpha chars and convert to lowercase --
'---------------------------------------------------------
Dim iPtr As Integer
Dim sChar As String
Dim sResult As String

sResult = ""
For iPtr = 1 To Len(String1)
    sChar = LCase$(Mid$(String1, iPtr, 1))
    If sChar <> UCase$(sChar) Then sResult = sResult & sChar
Next iPtr
NormaliseStringAtoZ = sResult
End Function

'********************************
'*** Compute Levenshtein Distance
'********************************

Public Function LevenshteinDistance(ByVal s As String, ByVal t As String) As Integer
Dim d() As Integer ' matrix
Dim m As Integer ' length of t
Dim N As Integer ' length of s
Dim I As Integer ' iterates through s
Dim j As Integer ' iterates through t
Dim s_i As String ' ith character of s
Dim t_j As String ' jth character of t
Dim cost As Integer ' cost

  ' Step 1

  N = Len(s)
  m = Len(t)
  If N = 0 Then
    LevenshteinDistance = m
    Exit Function
  End If
  If m = 0 Then
    LevenshteinDistance = N
    Exit Function
  End If
  ReDim d(0 To N, 0 To m) As Integer

  ' Step 2

  For I = 0 To N
    d(I, 0) = I
  Next I

  For j = 0 To m
    d(0, j) = j
  Next j

  ' Step 3

  For I = 1 To N

    s_i = Mid$(s, I, 1)

    ' Step 4

    For j = 1 To m

      t_j = Mid$(t, j, 1)

      ' Step 5

      If s_i = t_j Then
        cost = 0
      Else
        cost = 1
      End If

      ' Step 6

      d(I, j) = WorksheetFunction.Min(d(I - 1, j) + 1, d(I, j - 1) + 1, d(I - 1, j - 1) + cost)

    Next j

  Next I

  ' Step 7

  LevenshteinDistance = d(N, m)

End Function

evryone. thankyou for your help!!