VBA - Search and remove duplicates

Question

I'm looking for an algorithm for which I do not have the VBA knowledge to script myself. So I'm stuck. It isn't through lack of effort trying because I have given it a go (plus, this bit of code is the last remaining piece of my bigger VBA code) I simply lack the knowledge/experience/skill...

Basically, I have an Excel file. In this file is a sheet, "sheet1". Sheet1 contains many rows of data. The number of rows contained in sheet1 can vary from 1 to n. Sometimes, I may have 50 while other times I may have 30, etc. What is consistent is the layout of the book, i.e. I have codes in column A which identify a product in my database.

What I want to do is this:

1. Scan the sheet for empty rows (due to the way the workbook is generated, I sometimes have blank rows) and remove them. These blank rows are sometimes in-between rows with data while at other times may be trailing at the end of the sheet.

2. After removing the blank rows find the last used row. Store that to a variable. I have found this piece of code useful for doing that:

mylastrow = myBook.Sheets("Results").Cells.Find(what:="*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row

3. Starting from the row determined in (2), I want to take the product code in A(x where x = mylastrow) and find any other occurrences of it (in column A). If any are found, delete that entire row corresponding to it. Importantly, this loop must go in reverse. For example let's say mylastrow = 40, the loop will need to begin at A40 and on the next iteration do A39 (or 38 if a row has been removed?). This is because with any of the product numbers the corresponding data in the row contains more data further down the column (because of the way the sheet was generated). Essentially the entry closest to the last row is the most recent.

Hopefully I've been able to explain the situ properly. But if not and you're willing to take the challenge (my burden?) off me I would be very grateful.

QF

Answer 1

The only way to develop that knowledge and skill is to get in there and code! I'm sure someone may come in and write you the entire procedure, but in the meantime these resources should give you the tools to do it yourself.

First, check out the method here to delete blank rows. It relies on "Selection" for the range, so you can either manually select all the cells of the sheet, then run the macro, or replace it with the following:

Dim r as range
set r = Sheet1.Cells 'now use r instead of Selection

OR (even better) use your code for finding the last used row and set the range from row 1 to "mylastrow".

Next, beginning from "mylastrow", start adding the values in Column A to a Dictionary object (example here). You can use a row counter to decrement from "mylastrow" to 1. Here's an example of how it would work. The key is assumed to be in the 1st column ("A").

Dim dict As Object
Dim rowCount As Long
Dim strVal As String

Set dict = CreateObject("Scripting.Dictionary")

rowCount = Sheet1.Range("A1").CurrentRegion.Rows.Count

Do While rowCount > 1
  strVal = Sheet1.Cells(rowCount, 1).Value2

  If dict.exists(strVal) Then
    Sheet1.Rows(rowCount).EntireRow.Delete
  Else
    dict.Add strVal, 0
  End If

  rowCount = rowCount - 1
Loop

Set dict = Nothing

Before: After:

Note that the 1st row hasn't been touched since we stopped when rowCount is 1 (assumes there's a header).