How to move UsedRange into Array for processing tasks and then copy back to the sheet? - excel

Question

Regarding this question “combine or merge cells with the same values vertically and horizontally” Link,
the provided answer (edited one) it works ,but with big range (e.g. 30 thousands rows) the macro takes a very long time to finish (no error raised but excel is not responding).
so, instead of putting only the first column on array,
Is it possible to move all the usedRange into array and processing all the tasks on memory and then copy back to the sheet?
I do not care about any lost format at all (fonts, rows height,..).
In advance, grateful for your helps.
Sub DeleteSimilarRows_AppendLastColuns()
Dim LastRow As Long, ws As Worksheet, arrWork, rngDel As Range, i As Long, j As Long, k As Long
Dim strVal As String, m As Long, boolNoFilter As Boolean
Set ws = ActiveSheet: LastRow = ws.Cells(ws.Rows.Count, 1).End(xlUp).Row
arrWork = ws.Range("A1:A" & LastRow).Value2 'Place the range in an array to make iteration faster
Application.DisplayAlerts = False: Application.ScreenUpdating = False
For i = 2 To UBound(arrWork) - 1 'Iterate between the array elements:
If arrWork(i, 1) = arrWork(i + 1, 1) Then
'Determine how many consecutive similar rows exist:__________________
For k = 1 To LastRow
If i + k + 1 >= UBound(arrWork) Then Exit For
If arrWork(i, 1) <> arrWork(i + k + 1, 1) Then Exit For
Next k '___________________________________________
For j = 14 To 14 'Build the concatenated string of cells in range "N":
strVal = ws.Cells(i, j).Value
For m = 1 To k
strVal = strVal & vbLf & ws.Cells(i + m, j).Value
Next m
ws.Cells(i, j).Value = strVal: strVal = ""
Next j
For m = 1 To k 'Place the cells for rows to be deleted in a Union range, to delete at the end, at once
If rngDel Is Nothing Then
Set rngDel = ws.Range("A" & i + m)
Else
Set rngDel = Union(rngDel, ws.Range("A" & i + m))
End If
Next m
i = i + k: If i >= UBound(arrWork) - 1 Then Exit For 'Increment the i variable and exiting if the resulted value exits the array size
End If
Next i
If Not rngDel Is Nothing Then rngDel.EntireRow.Delete 'Delete the not necessary rows
Application.DisplayAlerts = True: Application.ScreenUpdating = True
End Sub

Answer 1

It is not only possible, but preferable. The speed increase is insane. This is how I do it:
Data from the spread sheet gets saved into a variable from type Variant -- the result is a 2-dimensional array (even if there is only one row/column in the range).
' Read data into Array
Dim data as Variant ' Important: has to be type Variant.
Set data = ActiveSheet.UsedRange.Value2 ' .Value or .Value2, as needed
When saving data back into the sheet, this code automatically selects a range of the appropriate size.
' Write array into cells
Dim target as Range
Set target = ActiveSheet.Cells(1,1) ' Start at A1 / R1C1; Change as appropriate
target.Resize(UBound(data, 1), UBound(data, 2)).Value = data