Speed up checking every cell in a dynamic range - excel

Question

I need to speed up this macro & to avoid specifying a range as (A2:A2000) for example because my data is dynamic.
My macro checks every cell with the same value in some columns to merge it
Sub Merge_Duplicated_Cells()
'
Application.DisplayAlerts = False
Application.ScreenUpdating = False
Dim ws As Worksheet
Dim Cell As Range
' Merge Duplicated Cells
Application.DisplayAlerts = False
Sheets("1").Select
Set myrange = Range("A2:A2000, B2:B2000, L2:L2000, M2:M2000, N2:N2000, O2:O2000")
CheckAgain:
For Each Cell In myrange
If Cell.Value = Cell.Offset(1, 0).Value And Not IsEmpty(Cell) Then
Range(Cell, Cell.Offset(1, 0)).Merge
Cell.VerticalAlignment = xlCenter
GoTo CheckAgain
End If
Next
Sheets("2").Select
Set myrange = Range("A2:A2000, B2:B2000, L2:L2000, M2:M2000, N2:N2000, O2:O2000")
For Each Cell In myrange
If Cell.Value = Cell.Offset(1, 0).Value And Not IsEmpty(Cell) Then
Range(Cell, Cell.Offset(1, 0)).Merge
Cell.VerticalAlignment = xlCenter
GoTo CheckAgain
End If
Next
ActiveWorkbook.Save
MsgBox "Report is ready"
Application.DisplayAlerts = True
Application.ScreenUpdating = True
End Sub

Answer 1

For a quick fix add
Application.Calculation = xlManual
after your code
Application.DisplayAlerts = False
Application.ScreenUpdating = False
and
Application.Calculation = xlAutomatic
after your code
Application.DisplayAlerts = True
Application.ScreenUpdating = True
and to improve the macro not processing blank ranges,
dim ws as worksheet
dim lastrowA, lastrowB, lastrow C as long
'Instead of setting last row to 2000, can use the actual last row by eg:
'find last row of data in column A'
lastrowA = ws.Cells(Rows.Count, 1).End(xlUp).Row
'find last row of data in column B'
lastrowB = ws.Cells(Rows.Count, 2).End(xlUp).Row
'find last row of data in column C'
lastrowC = ws.Cells(Rows.Count, 3).End(xlUp).Row
and insert these into the macro instead of 2000 eg:
Set myrange = Range("A2:A" & lastrowA & ,

Answer 2

The slowdown in your code is primarily due to the presence of the GoTo CheckAgain transition, due to which the cycle of processing the same cells is repeated many times. In addition, multiple calls to the cells of the sheet are used, which is very time consuming. In the code below, unnecessary cycles are excluded, reading data from the sheet, merging and formatting cells are performed immediately for the entire processed subrange.
I ran the code on 2 sheets with 10000 rows each, it took 2.6 sec.
Option Explicit
Sub test1()
'Here we indicate only the starting cells in each column, because
'the size of the non-empty area in these columns is calculated
'automatically in the MergeCells() procedure
MergeCells Sheets("1").Range("A2,B2,L2,M2,N2,O2")
MergeCells Sheets("2").Range("A2,B2,L2,M2,N2,O2")
End Sub
Sub MergeCells(myrange As Range)
Dim v As Variant, col As Range, Cell As Range, toMerge(0 To 1) As Range, k As Long, index As Byte, area As Variant, arr As Variant, skip As Boolean
With Application
.DisplayAlerts = False
.ScreenUpdating = False
.Calculation = xlCalculationManual
For Each col In myrange
' next line reads all the data from sheet's column at once
arr = col.Resize(myrange.Parent.Cells(Rows.Count, col.Column).End(xlUp).Row - col.Row + 1)
For k = LBound(arr, 1) To UBound(arr, 1) - 1 'loop through all rows of an array
If Not skip And arr(k, 1) = arr(k + 1, 1) And Not IsEmpty(arr(k, 1)) Then
'to prevent "gluing" adjacent sub-ranges within the same range,
'two ranges are used in the toMerge array, all odd sub-ranges are collected
'in the element with index 0, all even ranges are collected in the element
'with index 1, and Index switches from 0 to 1 and vice versa after each array subrange
If toMerge(index) Is Nothing Then
Set toMerge(index) = col.Offset(k - col.Row + 1).Resize(2)
Else
Set toMerge(index) = Union(col.Offset(k - col.Row + 1).Resize(2), toMerge(index))
End If
index = 1 - index
skip = True ' if merged, skip next cell
Else
skip = False
End If
Next
' if the ranges for merge are non-empty, we merge and format simultaneously for all subranges
For Each area In toMerge
If Not area Is Nothing Then
area.Merge
area.VerticalAlignment = XlVAlign.xlVAlignCenter
End If
Next
Set toMerge(0) = Nothing
Set toMerge(1) = Nothing
Next
.DisplayAlerts = True
.ScreenUpdating = True
.Calculation = xlCalculationAutomatic
End With
End Sub

Answer 3

If I understand you correctly .... besides the already existing answer, another way (which is not meant to be better) maybe something like this :
Before and after running the sub (please ignore the yellow fill and the border, as it is used just to be easier to see the result) like image below :
===>
Sub test()
Dim LR As Integer: Dim cnt As Integer
Dim i As Integer: Dim c As Range
Application.DisplayAlerts = False
With ActiveSheet.UsedRange
LR = .Rows(.Rows.Count).Row
cnt = .Columns.Count
End With
For i = 1 To cnt
Set c = Cells(1, i)
Do
If c.Value <> "" And c.Value = c.Offset(1, 0).Value _
Then Range(c, c.Offset(1, 0)).Merge _
Else Set c = c.Offset(1, 0)
Loop Until c.Row > LR
Next
End Sub
LR is the last row of the used range of the active sheet.
cnt is the column count of the used range of the active sheet.
Then it loop from 1 to as many as the cnt as i variable.
Inside this loop, it create the starting cell as c variable, then do the inner loop, by checking each c within the looped column (the i in cnt) if the row below c has the same value then it merge this c and the c.offset(1,0). The inner loop stop when the c.row is larger than the LR, then it goes to the next i (the next column).
Please note, the data should start from column A ... because the outer loop assume that the column to be in the inner loop will start from column 1 (column A). And also, the code doesn't do any fancy things, such as alignment, font size, border, etc.