Loop to replicate values into an array - arrays

Question

I’m in a situation where I need to reproduce something in VBA and a bit stuck given my lack of understanding of object oriented language and VBA in general.
Problem:
I need to produce an array or vector based on a 2 column table.
The first range (column) contains unit counts.
The second range (column) contains numeric values.
I need to replicate the value based on the number of units.
For example,
if the first row contains 3 units with a value of $100
I need the array to contain $100, $100, $100.
This will need to be looped thru each row containing units.
So if row 2 contains 2 units with a value of $50
I need to complete array to be $100, $100, $100, $50, $50, and so on.
I understand this situation will require ReDim the array based on the total values. My struggle is I’ve been unable to figure out the nested for loops.
I get how to replicate the value based on the number of “units” like the below...
ReDim arr(0 To x - 1)
For i = 0 To x - 1
arr(i) = rng.Offset(0, 1).Value
Next
What is the best way to loop thru each row and replicate the values for each row in the range based on the unit count?
If anyone is familiar with R, I'm essentially looking for something that achieves the rep() function (e.g., rep(df$b, df$a)) and return the values in a single array.
Any help is greatly appreciated. Thanks

Answer 1

Or a one liner which uses the REPT function as you would have used in r :)
This assumes your data is in A1:B10 - the length can be made variable
s = Split(Join(Application.Transpose(Evaluate("=INDEx(REPT(B1:B10&"","",A1:A10),,1)"))), ",")
An an example, to dump the new to array to C1
s = Split(Join(Application.Transpose(Evaluate("=INDEx(REPT(B1:B10&"","",A1:A10),,1)"))), ",")
[c1].Resize(UBound(s), 1) = Application.Transpose(s)

Answer 2

When you say Row contains 3 units, do you mean the cell has value 3 or 3 Units? If it is 3 then you may not have to Redim the array in the loop. Simply find the sum of values in Col A which has units and Redim it in one go as shown below.
Sub Sample()
Dim ws As Worksheet
Dim Ar() As String
Dim n As Long, i As Long, lRow As Long
'~~> Change this to the relevant sheet
Set ws = Sheet6
With ws
n = Application.WorksheetFunction.Sum(.Columns(1))
ReDim Ar(t To n)
lRow = .Range("A" & .Rows.Count).End(xlUp).Row
n = 1
For i = 1 To lRow
If Len(Trim(.Range("A" & i).Value)) <> 0 Then
For j = 1 To .Range("A" & i).Value
Ar(n) = .Range("B" & i).Value
n = n + 1
Next j
End If
Next i
For i = LBound(Ar) To UBound(Ar)
Debug.Print Ar(i)
Next i
End With
End Sub
Screenshot
And if the cell has 3 Units then you will have to store the values of Col A in an array, do a replace on Unit/Units, find the sum and finally use the above code. Here is an example
Sub Sample()
Dim ws As Worksheet
Dim Ar() As String, tmpAr As Variant
Dim n As Long, i As Long, j As Long, k As Long, lRow As Long
'~~> Change this to the relevant sheet
Set ws = Sheet6
With ws
lRow = .Range("A" & .Rows.Count).End(xlUp).Row
tmpAr = .Range("A1:A" & lRow).Value
For i = LBound(tmpAr) To UBound(tmpAr)
tmpAr(i, 1) = Replace(tmpAr(i, 1), "Units", "")
tmpAr(i, 1) = Trim(Replace(tmpAr(i, 1), "Unit", ""))
n = n + Val(tmpAr(i, 1))
Next i
ReDim Ar(t To n)
n = 1
For i = 1 To lRow
If Len(Trim(.Range("A" & i).Value)) <> 0 Then
k = Val(Trim(Replace(Replace(.Range("A" & i).Value, "Units", ""), "Unit", "")))
For j = 1 To k
Ar(n) = .Range("B" & i).Value
n = n + 1
Next j
End If
Next i
For i = 1 To UBound(Ar)
Debug.Print Ar(i)
Next i
End With
End Sub
Screenshot

Answer 3

if your data is already in an array then ReDim'ing will delete it's contents. You can ReDim Preserve but it's an expensive operation, better to create a new array to put the results into.
I have assumed the data is contained within a Named Range called "Data" with Units being the first column and Values being the second column.
if your data changes regularly you can create a dynamic range using the OFFSET function i.e. =OFFSET(Sheet1!$A$1,0,0,COUNTA(Sheet1!$A:$A),2) assuming your data starts in cell A1 and there is no header row.
Sub ProcessData()
Dim DataArr() As Variant
Dim QtyColArr() As Variant
Dim ResultArr() As Variant
Dim TotalQty As Long
Dim i As Long, j As Long, k As Long
'store data into array
DataArr = Range("Data") 'assume data stored in named range called "Data"
'store Qty col into 1D array
QtyColArr = Range("Data").Resize(, 1)
'sum all qty vals
TotalQty = Application.Sum(QtyColArr)
're-size ResultsArray
ReDim ResultArr(1 To TotalQty)
'Initialize ResultsArr counter
k = LBound(ResultArr)
'loop DataArr
For i = LBound(DataArr) To UBound(DataArr)
'loop qty for current row
For j = 1 To DataArr(i, 1)
'copy value
ResultArr(k) = DataArr(i, 2)
'iterate ResultsArr counter
k = k + 1
Next j
Next i
'output to intermediate window
Debug.Print "{" & Join(ResultArr) & "}"
End Sub