Queryable::Aggregate<TSource, TAccumulate> Method (IQueryable<TSource>^, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>^>^)

 

Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.

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

public:
generic<typename TSource, typename TAccumulate>
[ExtensionAttribute]
static TAccumulate Aggregate(
	IQueryable<TSource>^ source,
	TAccumulate seed,
	Expression<Func<TAccumulate, TSource, TAccumulate>^>^ func
)

Parameters

source
Type: System.Linq::IQueryable<TSource>^

A sequence to aggregate over.

seed
Type: TAccumulate

The initial accumulator value.

func
Type: System.Linq.Expressions::Expression<Func<TAccumulate, TSource, TAccumulate>^>^

An accumulator function to invoke on each element.

Return Value

Type: TAccumulate

The final accumulator value.

Type Parameters

TSource

The type of the elements of source.

TAccumulate

The type of the accumulator value.

Exception Condition
ArgumentNullException

source or func is null.

This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T, TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

The Aggregate<TSource, TAccumulate>(IQueryable<TSource>^, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>^>^) method generates a MethodCallExpression that represents calling Aggregate<TSource, TAccumulate>(IQueryable<TSource>^, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>^>^) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression^) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Aggregate<TSource, TAccumulate>(IQueryable<TSource>^, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>^>^) depends on the implementation of the type of the source parameter. The expected behavior is that the specified function, func, is applied to each value in the source sequence and the accumulated value is returned. The seed parameter is used as the seed value for the accumulated value, which corresponds to the first parameter in func.

To simplify common aggregation operations, the set of standard query operators also includes two counting methods, Count<TSource> and LongCount<TSource>, and four numeric aggregation methods, namely Max<TSource>, Min<TSource>, Sum, and Average.

The following code example demonstrates how to use Aggregate<TSource, TAccumulate>(IQueryable<TSource>^, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>^>^) to apply an accumulator function when a seed value is provided to the function.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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