Step 1: Writing the VBA code

First, let’s create the VBA code that opens an Excel workbook. VBA, or Visual Basic for Applications, is a programming language built into Excel that allows you to automate repetitive tasks. Below is a simple VBA script to open a workbook from a specified path:

Sub OpenWorkbook()
    Dim workbookPath As String
    Dim workbook As Workbook
    
    ' Specify the path to your workbook
    workbookPath = "C:\Path\To\Your\Workbook.xlsx"
    
    ' Open the workbook
    Set workbook = Workbooks.Open(workbookPath)
    
    ' Optional: Make the workbook visible
    workbook.Application.Visible = True
End Sub

Explanation:

• Dim workbookPath as string: This line declares a variable named workbookPath to save the file path of the workbook.
• Dim Workbook As Workbook: This declares a variable workbook that holds the workbook object after it is opened.
• workbookPath = “C:.xlsx”: Replace the temporary path with the actual path to your Excel file.
• Set Workbook = Workbooks.Open(workbookPath): This line opens the workbook and assigns it to the workbook variable.
• workbook.Application.Visible = True: This optional rule makes the Excel application visible after the workbook is opened.

Step 2: Testing the VBA code

Before proceeding with the R script, it is important to test the VBA code directly in Excel to ensure it works correctly.

1. Open Excel and press ALT + F11 to access the VBA editor.
2. Insert a new module by clicking Insert > Module.
3. Copy and paste the above VBA code into the module.
4. Enter the OpenWorkbook macro by pressing F5 or by selecting Run > Run Sub/UserForm.

Once the workbook opens successfully, you are ready to integrate it with R.

Step 3: Call the VBA code from R

Now that we have the VBA macro ready, we can call it from R using the RDCOMClient package. The following R code initializes Excel, runs the VBA macro to open the workbook, and then optionally closes Excel.

library(RDCOMClient)

# Initialize the COM object for Excel
excelApp 
Explanation:

• library(RDCOMClient): This loads the RDCOMClient package, which allows R to communicate with Excel via COM (Component Object Model).
• COMCreate(“Excel.Application”): This line creates a COM object representing the Excel application, which allows R to control Excel.
• fn : Replace this with the actual path to your Excel file. Note the double backslashes (\\) are needed to correctly format the path in R.
• xlWbk Open(fn): This line opens the specified Excel workbook using the path stored in fn.
• excelApp((“Visible”)): This optional line makes the Excel application visible, so you can see the workbook open.
• excelApp$Quit(): This line closes Excel after the script has run. If you would rather keep Excel open, you can leave this line out or comment it out.

Step 4: Execute the R script

Once the R script is ready, you can run it in your R environment to open the workbook using the VBA macro. This integration between R and Excel is powerful for automating tasks, especially when you need to process Excel files programmatically.