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

Computes the average of a sequence of 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 double Average<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, long> selector

Type Parameters


The type of the elements of source.


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

Return Value

Type: System.Double
The average of the sequence of values.

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.


source or selector is null.


source contains no elements.


The sum of the elements in the sequence is larger than MaxValue.

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

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

      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. 


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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