How to Remove Duplicates from VBA Array in 3 Minutes (Excel)

Written by Kasper Langmann

Excel is a powerful tool that can be used for a myriad of tasks. One of these tasks includes managing and manipulating arrays using Visual Basic for Applications (VBA). One common issue that arises when dealing with arrays is the presence of duplicate values. This article will guide you through the process of removing duplicates from a VBA array in Excel in just three minutes.

Understanding VBA Arrays

Before diving into the process of removing duplicates, it’s crucial to understand what VBA arrays are. In Excel, an array is a data structure that stores a collection of values. These values can be of any data type, including numbers, strings, dates, and objects. Arrays are incredibly useful when you need to perform operations on a large number of values at once.

VBA arrays are dynamic, meaning they can change in size during the runtime of a program. This makes them incredibly flexible and powerful. However, this flexibility also means that they can become cluttered with duplicate values, especially when dealing with large datasets.

Why Remove Duplicates?

Duplicate values in an array can lead to inaccurate results when performing calculations or analyses. For example, if you’re calculating the average value of an array and there are duplicates, the average will be skewed. Similarly, if you’re performing a unique count of values in an array, duplicates will inflate the count.

Removing duplicates from an array ensures that your data is accurate and reliable, leading to more accurate results and analyses. It’s a crucial step in data cleaning and preparation, especially when dealing with large datasets.

Removing Duplicates from VBA Array

Now that we understand what VBA arrays are and why it’s important to remove duplicates, let’s dive into the process. The method we’ll be using involves the use of a Collection object, which is a special type of object in VBA that can hold a set of related items.

The Collection object has a unique property: when you try to add an item to a Collection that already exists in it, VBA will throw an error. We can use this property to our advantage to remove duplicates from an array.

Step 1: Create a New Collection

The first step in removing duplicates from an array is to create a new Collection. This can be done using the New keyword, like so:

Dim coll As New Collection

This line of code creates a new Collection object that we’ll use to store the unique values from our array.

Step 2: Loop Through the Array

The next step is to loop through the array and add each value to the Collection. We’ll use a For Each loop for this, which is a type of loop that iterates over each item in a collection (in this case, our array).

For Each item In array
    coll.Add item
Next item

This code will attempt to add each item in the array to the Collection. If the item already exists in the Collection, VBA will throw an error.

Step 3: Handle Errors

To prevent our program from crashing when an error occurs, we’ll use error handling. This involves using the On Error Resume Next statement, which tells VBA to continue with the next line of code when an error occurs.

On Error Resume Next

With this line of code, if VBA encounters an error when trying to add an item to the Collection (which will happen if the item is a duplicate), it will simply skip that item and continue with the next one.

Step 4: Convert the Collection Back to an Array

The final step is to convert the Collection back to an array. This can be done using the ToArray method of the Collection object.

array = coll.ToArray()

This line of code converts the Collection back to an array, effectively removing all duplicates.

Conclusion

Removing duplicates from a VBA array in Excel is a straightforward process that can be accomplished in just three minutes. By understanding the nature of VBA arrays and using the unique properties of the Collection object, you can ensure that your data is accurate and reliable.

Remember, data cleaning and preparation is a crucial step in any data analysis process. By removing duplicates from your arrays, you’re ensuring that your analyses and calculations are based on accurate data, leading to more reliable results.