VLOOKUP() Alternative using Arrays - arrays

Question

I’ve been experimenting with arrays to find a faster alternative to VLOOKUP(), which can take a long time to execute with very large data sets.
I searched SO and many other sites, grabbing snippets of code.
The data:
A1:A5 the list of values to lookup (1,2,3,4,5)
C1:C5 the range to ‘find’ the values (2,4,6,8,10)
D1:D5 the range of values to ‘return’ (a,b,c,d,e)
B1:B5 is where I’d like to paste the ‘looked-up’ values.
The code works up to a point, in that it does return correct values for the ‘looked-up’ value’s position in C1:C5 – and the correct values in the adjacent cells in D1:D5.
When I try to load the returned values to Arr4 (the array to be pasted back to the sheet) which is saying <Type mismatch> when I hover the mouse over it. It doesn’t stop the code from executing, but it doesn’t paste anything.
My questions are:
How do I populate the array Arr4 with the myVal2 values, and
How do I paste it back to the sheet?
Option Explicit
Sub testArray()
Dim ArrLookupValues As Variant
ArrLookupValues = Sheet1.Range("A1:A5") 'The Lookup Values
Dim ArrLookupRange As Variant
ArrLookupRange = Sheet1.Range("C1:C5") 'The Range to find the Value
Dim ArrReturnValues As Variant
ArrReturnValues = Sheet1.Range("D1:D5") 'The adjacent Range to return the Lookup Value
Dim ArrOutput As Variant 'output array
Dim UpperElement As Long
UpperElement = UBound(ArrLookupValues) 'Used purely for the ReDim statement
Dim i As Long
For i = LBound(ArrLookupValues) To UBound(ArrLookupValues)
Dim myVal As Variant
myVal = ArrLookupValues(i, 1)
Dim pos As Variant 'variant becaus it can return an error
pos = Application.Match(myVal, ArrLookupRange, 0) 'pos always returns the correct position
Dim myVal2 As Variant
If Not IsError(pos) Then
myVal2 = ArrReturnValues(pos, 1) 'myVal2 always returns the correct value
ReDim Preserve ArrOutput(1 To UpperElement, 1 To 1)
ArrOutput(i, 1) = myVal2
Else
ReDim Preserve ArrOutput(1 To UpperElement, 1 To 1)
myVal2 = "Not Found"
ArrOutput(i, 1) = myVal2
End If
Next i
Dim Destination As Range
Set Destination = Range("B1")
Destination.Resize(UBound(ArrOutput, 1), UBound(ArrOutput, 2)).Value =
ArrOutput
End Sub

Answer 1

According to #T.M 's answer, you can even do that without looping just by using VLookup instead of Match:
Public Sub testArraya()
With Sheet1
Dim ArrLookupValues() As Variant
ArrLookupValues = .Range("A1:A5").Value ' lookup values 1,2,3,4,5,6
Dim ArrLookupReturnRange() As Variant ' lookup range items 2,4,6,8,10
ArrLookupReturnRange = .Range("C1:D5").Value ' And return column D a,b,c,d,e
End With
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'[1] Match all values at once and return other values of column D
' (found position indices or Error 2042 if not found)
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dim ArrOutput() As Variant
ArrOutput = Application.VLookup(ArrLookupValues, ArrLookupReturnRange, 2, 0)
'[3] write results to any wanted target
Dim Destination As Range
Set Destination = Sheet1.Range("B1") ' ‹‹ change to your needs
Destination.Resize(UBound(ArrOutput, 1), UBound(ArrOutput, 2)).Value = ArrOutput
End Sub
Or even extremly shortened and almost a one liner:
Public Sub testArrayShort()
Const nRows As Long = 5 'amount of rows
With Sheet1
.Range("B1").Resize(nRows).Value = Application.VLookup(.Range("A1").Resize(nRows).Value, .Range("C1:D1").Resize(nRows).Value, 2, 0)
End With
End Sub

Answer 2

Use proper error handling and an If statement instead of On Error Resume Next.
Also your Arr4 needs to be 2 dimensional like your other arrays. Even if it is only one column it needs no be Arr4(1 To UpperElement, 1 To 1) and Arr4(i, 1) = myVal2. Ranges are always 2 dimensional (row, column) even if there is only one column.
And I highly recommend to rename your array variables. When ever you feel like you have to give your variable numbers, you can be sure you are doing it wrong.
Rename them like following for example:
Arr1 --› ArrLookupValues
Arr2 --› ArrLookupRange
Arr3 --› ArrReturnValues
Arr4 --› ArrOutput
This is only a simple modification but your code will extremely gain in human readability and maintainability. You even don't need comments to describe the arrays because their names are self descriptive now.
Finally your output array can be declared the same size as the input arrays. Using ReDim Preserve makes your code slow, so avoid using it.
So something like this should work:
Option Explicit
Public Sub testArray()
Dim ArrLookupValues() As Variant
ArrLookupValues = Sheet1.Range("A1:A5").Value
Dim ArrLookupRange() As Variant
ArrLookupRange = Sheet1.Range("C1:C5").Value
Dim ArrReturnValues() As Variant
ArrReturnValues = Sheet1.Range("D1:D5").Value
Dim UpperElement As Long
UpperElement = UBound(ArrLookupValues, 1)
'create an empty array (same row count as ArrLookupValues)
ReDim ArrOutput(1 To UpperElement, 1 To 1)
Dim i As Long
For i = LBound(ArrLookupValues, 1) To UBound(ArrLookupValues, 1)
Dim FoundAt As Variant 'variant because it can return an error
FoundAt = Application.Match(ArrLookupValues(i, 1), ArrLookupRange, 0) 'pos always returns the correct position
If Not IsError(FoundAt) Then
ArrOutput(i, 1) = ArrReturnValues(FoundAt, 1)
Else
ArrOutput(i, 1) = "Not Found"
End If
Next i
Dim Destination As Range
Set Destination = Range("B1") 'make sure to specify a sheet for that range!
Destination.Resize(UBound(ArrOutput, 1), UBound(ArrOutput, 2)).Value = ArrOutput
End Sub

Answer 3

Just for fun a slight modification of #PEH 's valid approach demonstrating a rather unknown way to excecute a single Match checking both arrays instead of repeated matches:
Public Sub testArray()
With Sheet1
Dim ArrLookupValues As Variant
ArrLookupValues = .Range("A1:A5").Value ' lookup values 1,2,3,4,5,6
Dim ArrLookupRange As Variant ' lookup range items 2,4,6,8,10
ArrLookupRange = .Range("C1:C5").Value
Dim ArrReturnValues As Variant ' return column D a,b,c,d,e
ArrReturnValues = .Range("D1:D5").Value
End With
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'[1] Match all item indices within ArrLookupRange at once
' (found position indices or Error 2042 if not found)
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dim ArrOutput
ArrOutput = Application.Match(ArrLookupValues, ArrLookupRange, 0)
'[2] change indices by return values
Dim i As Long
For i = 1 To UBound(ArrOutput)
If Not IsError(ArrOutput(i, 1)) Then
ArrOutput(i, 1) = ArrReturnValues(ArrOutput(i, 1), 1)
' Else
' ArrOutput(i, 1) = "Not Found" ' optional Not Found statement instead of #NV
End If
Next i
'[3] write results to any wanted target
Dim Destination As Range
Set Destination = Sheet1.Range("B1") '<< change to your needs
Destination.Resize(UBound(ArrOutput, 1), UBound(ArrOutput, 2)).Value = ArrOutput
End Sub