Optimize my search and copy code - excel

Question

I have an Excel project which has a few thousand rows containing strings which need sorting out.
Typically one cell in each row should have a six digit number 123456 but many are 123456/123456/234567 etc. which need to have the / deleted and then be separated onto individual rows. There is other information in the surrounding columns which needs to stay with these six digit numbers.
I decided to approach this by firstly making copies of the rows the appropriate number of times and then deleting the surplus information
This code below deals with the copying part and it works.. but it's really slow. Is there a quicker way to achieve what I'm trying to do?
Thanks for any help.
Chris
Sub Copy_extra_rows()
Application.ScreenUpdating = False
s = 2
Do Until s = Range("N20000").End(xlUp).Row
'checks for / in Mod list
If InStr(1, Range("N" & s), "/") Then
'determines number of /
x = Len(Range("N" & s)) - Len(Replace(Range("N" & s), "/", ""))
'loops x times and copies new row
For a = 1 To x
Range("J" & s & ":O" & s).Select
Selection.Copy
Range("J" & s + 1).Select
Selection.Insert Shift:=xlDown
s = s + 1
Next a
Else
End If
s = s + 1
Loop
End Sub

Answer 1

I would have approached this differently to optimize the process and improve the overall efficiency of code.
Firstly, I would load the entire column into an array. This way it's always faster to access the elements of that array rather then referring Cells() multiple times in loops. Working with objects in memory is much faster because your client doesn't need to for example update the UI. Generally, arrays big O is O(1) which means you instantly can access an object/data stored at a specific index.
Let's consider an SSCCE.
Then the code (*Note: I have added comments in the code in the right places, hopefully that helps you understand what is going on)
Sub Main()
Dim columnArray As Variant
' create an array from Range starting at L2 to the last row filled with data
columnArray = Range("N2:N" & Range("N" & Rows.Count).End(xlUp).Row)
Dim c As New Collection
' add separate 6 digit numbers to the collection as separate items
' iterate the columnArray array and split the contents
Dim element As Variant
For Each element In columnArray
If NeedSplitting(element) Then
Dim splittedElements As Variant
splittedElements = Split(element, "/")
Dim splittedElement As Variant
For Each splittedElement In splittedElements
c.Add splittedElement
Next
Else
c.Add element
End If
Next
' print the collection to column Q
PrintToColumn c, "Q"
End Sub
Private Sub PrintToColumn(c As Collection, ByVal toColumn As String)
Application.ScreenUpdating = False
' clear the column before printing
Columns(toColumn).ClearContents
' iterate collection and print each item on a new row in the specified column
Dim element As Variant
For Each element In c
Range(toColumn & Range(toColumn & Rows.Count).End(xlUp).Row + 1) = element
Next
Application.ScreenUpdating = True
End Sub
Private Function NeedSplitting(cell As Variant) As Boolean
' returns true if the cell needs splitting
If UBound(Split(cell, "/")) > 0 Then
NeedSplitting = True
End If
End Function
After running the code all your numbers should appear as separate elements in column Q
NOTE: Why use a Collection?
Collections in VBA are dynamic. It means you don't have to know the size of a collection in order to use it - unlike arrays. You can re-dim your array multiple times to increase its size but that's rather considered a bad practice. You can add nearly as many items to a Collection as you want with a simple Collection.Add method and you don't have to worry about increasing the size manually - it's all done for you automatically. In this scenario the processing happens in memory so it should be much quicker then replacing cells contents inside a loop.

Answer 2

Try this:
Dim s As Integer
Dim splitted_array() As String
s = 2 'Assuming data starts at row 2
Do Until Range("N" & s).Value = vbNullString Or s >= Rows.Count
'Split the array
splitted_array = Split(Range("N" & s).Value, "/")
If UBound(splitted_array) > 0 Then
'Set the first value on the first row
Range("N" & s).Value = splitted_array(0)
For i = 1 To UBound(splitted_array)
'Add subsequent rows
Rows(s + i).Insert xlDown
Range("J" & s + i & ":O" & s + i).Value = Range("J" & s & ":O" & s).Value
Range("N" & s + i).Value = splitted_array(i)
Next
End If
s = s + 1 + UBound(splitted_array)
Loop
This code turns this:
into this: