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


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


Type: System.Collections.Generic.IEnumerable<TSource>

A sequence of values to calculate the average of.

Type: System.Func<TSource, Single>

A transform function to apply to each element.

Return Value

Type: System.Single

The average of the sequence of values.

Type Parameters


The type of the elements of source.

Exception Condition

source or selector is null.


source contains no elements.

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, Int32>) to calculate an average.


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[] fruits = { "apple", "banana", "mango", "orange", "passionfruit", "grape" };

double average = fruits.Average(s => s.Length);

Console.WriteLine("The average string length is {0}.", average);

// This code produces the following output:
// The average string length is 6.5. 

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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