Enumerable.Aggregate(TSource, TAccumulate, TResult) Method (IEnumerable(TSource), TAccumulate, Func(TAccumulate, TSource, TAccumulate), Func(TAccumulate, TResult))
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.
Assembly: System.Core (in System.Core.dll)
static member Aggregate : source:IEnumerable<'TSource> * seed:'TAccumulate * func:Func<'TAccumulate, 'TSource, 'TAccumulate> * resultSelector:Func<'TAccumulate, 'TResult> -> 'TResult
Type Parameters
- TSource
The type of the elements of source.
- TAccumulate
The type of the accumulator value.
- TResult
The type of the resulting value.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(TSource)
An IEnumerable(T) to aggregate over.
- seed
- Type: TAccumulate
The initial accumulator value.
- func
- Type: System.Func(TAccumulate, TSource, TAccumulate)
An accumulator function to be invoked on each element.
- resultSelector
- Type: System.Func(TAccumulate, TResult)
A function to transform the final accumulator value into the result value.
Return Value
Type: TResultThe transformed final accumulator value.
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. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).| Exception | Condition |
|---|---|
| ArgumentNullException | source or func or resultSelector is a null reference (Nothing in Visual Basic). |
The Aggregate(TSource, TAccumulate, TResult)(IEnumerable(TSource), TAccumulate, Func(TAccumulate, TSource, TAccumulate), Func(TAccumulate, TResult)) method makes it simple to perform a calculation over a sequence of values. This method works by calling func one time for each element in source. Each time func is called, Aggregate(TSource, TAccumulate, TResult)(IEnumerable(TSource), TAccumulate, Func(TAccumulate, TSource, TAccumulate), Func(TAccumulate, TResult)) passes both the element from the sequence and an aggregated value (as the first argument to func). The value of the seed parameter is used as the initial aggregate value. The result of func replaces the previous aggregated value. The final result of func is passed to resultSelector to obtain the final result of Aggregate(TSource, TAccumulate, TResult)(IEnumerable(TSource), TAccumulate, Func(TAccumulate, TSource, TAccumulate), Func(TAccumulate, TResult)).
To simplify common aggregation operations, the standard query operators also include a general purpose count method, Count, and four numeric aggregation methods, namely Min, Max, Sum, and Average.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.