it's not exactly transposing (that was my first thought)
and the transpose formula is built in to both excel and libreoffice (no need for an addin)
FWIW here's a bit of VBA I found on the web that does what you want, though the output is to a delimited string (pretty sure you can work it out from there)
Function MYVLOOKUP(lookupval, lookuprange As Range, indexcol As Long)
Dim r As Range
Dim result As String
result = ""
For Each r In lookuprange
If r = lookupval Then
result = result & "," & r.Offset(0, indexcol - 1)
End If
Next r
MYVLOOKUP = Right(result, Len(result) - 1)
End Function
paste it into your (excel) personal macro workbook, then call it as a user defined function from the FX dialog box (syntax is the same as a normal VLOOKUP)
Working with excel row and columnscredit for the code goes here -
http://www.mrexcel.c...ell-concatenate.html