Creating your own LINQ extension methods

In Chapter 6, Implementing Interfaces and Inheriting Classes, you learned how to create your own extension methods. To create LINQ extension methods, all you must do is extend the IEnumerable<T> type.

Good Practice: Put your own extension methods in a separate class library so that they can be easily deployed as their own assembly or NuGet package.

We will look at the Average extension method as an example. A well-educated school child will tell you that average can mean one of three things:

• Mean: Sum the numbers and divide by the count.
• Mode: The most common number.
• Median: The number in the middle of the numbers when ordered.

Microsoft's implementation of the Average extension method calculates the mean. We might want to define our own extension methods for Mode and Median.

1. In the LinqWithEFCore project, add a new class file named MyLinqExtensions.cs.
2. Modify the...