Find matches in 2 cols using Collection vs Dictionary

[GS]

I made a few changes that seem to improve performance so that 2 cols x
500000 rows processes in 6 to 8 secs on my machine now...


Function FilterMatches(Matches As Long, Criteria() As Variant) As
Boolean
' Compares 2 user-specified cols and filters matches found.
' User can also specific target col to receive resulting list.
' Optionally supports returning a unique list or allow duplicates.
' Optionally supports returning matches or non-matches.
'
' Args In: Matches: ByRef var to return number of matches found to
the caller.
'
' vCriteria(): A variant array containing the filtering
parameters.
' Criteria(0) - Address of the values to be filtered
' Criteria(1) - Address of the values to check
' Criteria(2) - Label of the column to put the filtered
list
' Criteria(3) - Numeric value to determine if we return
matches or non-matches
' Criteria(4) - Numeric value to determine if we return a
unique list or allow dupes
'
' Returns: True if matches found and no error occurs;
' False if a: matches not found --OR-- error occurs;

Dim i&, j& 'as long
Dim vFilterRng, vCheckRng, vResult, vaMatches(), vaNoMatches(),
vaDataOut() 'as variant
Dim bReturnMatches As Boolean, bMatch As Boolean, bDupesAllowed As
Boolean
Dim cItemsToCheck As New Collection, sMsg$, sRngOut$ 'as string

'Load the filtering criteria
vFilterRng = Range(Criteria(0)): vCheckRng = Range(Criteria(1)):
sRngOut = Criteria(2)
bReturnMatches = (Criteria(3) = 1): bDupesAllowed = (Criteria(4) = 1)
ReDim vaMatches(UBound(vFilterRng)): ReDim
vaNoMatches(UBound(vFilterRng)): j = 0

'Load the Collection with the values to be checked.
'Collections only allow unique keys so use OERN (no need to check if
they already exist)
Set cItemsToCheck = New Collection: On Error Resume Next
For i = LBound(vCheckRng) To UBound(vCheckRng)
cItemsToCheck.Add Key:=CStr(vCheckRng(i, 1)), Item:=vbNullString
Next 'i
Err.Clear

Debug.Print Now()
'Check the Collection for matches
On Error GoTo MatchFound
For i = LBound(vFilterRng) To UBound(vFilterRng)
bMatch = False '..reset
cItemsToCheck.Add Key:=CStr(vFilterRng(i, 1)), Item:=vbNullString
If bMatch Then
If bReturnMatches Then vaMatches(j) = vFilterRng(i, 1): j = j + 1
Else
vaNoMatches(j) = vFilterRng(i, 1): j = j + 1
cItemsToCheck.Remove CStr(vFilterRng(i, 1)) '..so dupes of it
don't get counted
End If 'bMatch
Next 'i

'Initialize the return list
If bReturnMatches Then vResult = vaMatches Else vResult = vaNoMatches

'Return a list of unique values?
If Not bDupesAllowed Then
On Error GoTo UniqueList
Dim cUniqueList As New Collection
For i = LBound(vResult) To UBound(vResult)
cUniqueList.Add Key:=CStr(vResult(i)), Item:=vbNullString
Next 'i
ReDim vaDataOut(cUniqueList.Count - 1, 0): j = 0
Else
ReDim vaDataOut(UBound(vResult), 0): j = 0
End If 'Not bDupesAllowed
Err.Clear: On Error GoTo ErrExit

'Make the list to return contiguous.
For i = LBound(vaDataOut) To UBound(vaDataOut)
If Not vResult(i) = Empty Then vaDataOut(j, 0) = vResult(i): j = j
+ 1
Next 'i

If Matches > 0 Then '..only write if Matches > 0
Columns(sRngOut).ClearContents
With Range(sRngOut & "1").Resize(UBound(vaDataOut) + 1, 1)
.Value = vaDataOut
.NumberFormat = "0000000000000" '..optional
.EntireColumn.AutoFit '..optional
End With
End If 'Matches > 0
Debug.Print Now()


ErrExit:
' If bReturnMatches Then Matches = UBound(vResult) ' + 1
FilterMatches = (Err = 0): Exit Function

MatchFound:
bMatch = True: Matches = Matches + 1: Resume Next

UniqueList:
vResult(i) = Empty: Matches = Matches + 1: Resume Next

End Function 'FilterMatches()