Enumerable.Average<TSource> Method (IEnumerable<TSource>, Func<TSource, Nullable<Int64>>)

July 28, 2014

Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

public static Nullable<double> Average<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, Nullable<long>> selector
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>
A sequence of values to calculate the average of.
selector
Type: System.Func<TSource, Nullable<Int64>>
A transform function to apply to each element.

Return Value

Type: System.Nullable<Double>
The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter.

In Visual Basic query expression syntax, an Aggregate Into Average() clause translates to an invocation of Enumerable.Average.

The following code example demonstrates how to use Average<TSource>(IEnumerable<TSource>, Func<TSource, Int64>) to calculate an average.

NoteNote:

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, change the body of the selector function.


      string[] numbers = { "10007", "37", "299846234235" };

      double average = numbers.Average(num => Convert.ToInt64(num));

      outputBlock.Text += String.Format("The average is {0}.", average) + "\n";

      // This code produces the following output:
      //
      // The average is 99948748093. 



Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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