# Levenshtein Distance During Load

**Steve Nase**Dec 4, 2015 12:04 PM

I have a question regarding data manipulations and calculations during the load script. I read some other discussions on the forum that talk about Levenshtein distance, which I'd like to use during my load. Here is what I'm trying to do - You may want to just read this description and refrain from looking at my script as I'm fairly certain it's far off what I actually want to do.

I have a list of invoices: (It will be much longer than this, I'm just starting simple)

LOAD * INLINE [ Invoice 1228357-0 1228382-0 1228356-0 1228355-0 ];

I want to get the average levenshtein distance of each invoice number from all the other invoice numbers. The entries with the lowest average numbers will be the most similar to each other. The problem I'm having is that the levenshtein function that I'm using takes two arguments and I can't figure out how to write my script to do what I want:

' Source: ' http://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Levenshtein_distance#VBScript Function levenshtein( a, b ) Dim i,j,cost,d,min1,min2,min3 ' Avoid calculations where there there are empty words If Len( a ) = 0 Then levenshtein = Len( b ): Exit Function If Len( b ) = 0 Then levenshtein = Len( a ): Exit Function ' Array initialization ReDim d( Len( a ), Len( b ) ) For i = 0 To Len( a ): d( i, 0 ) = i: Next For j = 0 To Len( b ): d( 0, j ) = j: Next ' Actual calculation For i = 1 To Len( a ) For j = 1 To Len( b ) If Mid(a, i, 1) = Mid(b, j, 1) Then cost = 0 Else cost = 1 End If ' Since min() function is not a part of VBScript, we'll "emulate" it below min1 = ( d( i - 1, j ) + 1 ) min2 = ( d( i, j - 1 ) + 1 ) min3 = ( d( i - 1, j - 1 ) + cost ) If min1 <= min2 And min1 <= min3 Then d( i, j ) = min1 ElseIf min2 <= min1 And min2 <= min3 Then d( i, j ) = min2 Else d( i, j ) = min3 End If Next Next levenshtein = d( Len( a ), Len( b ) ) End Function

This is my most recent attempt which gets me the distance of each of the invoices from the first invoice. It's a long way off from what I'm trying to accomplish:

LOAD RowNo() as Number, Invoice, levenshtein(Invoice, Peek(Invoice, 0)) as Distance, Peek(Invoice, 0) as Invoice2; LOAD * INLINE [ Invoice 1228357-0 1228382-0 1228356-0 1228355-0 ];

Any help to point me in the right direction would be appreciated.

Thanks in advance,

Steve