ToLookup(TSource, TKey, TElement) Method (ParallelQuery(TSource), Func(TSource, TKey), Func(TSource, TElement))

ParallelEnumerable::ToLookup<TSource, TKey, TElement> Method (ParallelQuery<TSource>^, Func<TSource, TKey>^, Func<TSource, TElement>^)

.NET Framework (current version)
 

Creates an ILookup<TKey, TElement> from a ParallelQuery<TSource> according to specified key selector and element selector functions.

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

public:
generic<typename TSource, typename TKey, typename TElement>
[ExtensionAttribute]
static ILookup<TKey, TElement>^ ToLookup(
	ParallelQuery<TSource>^ source,
	Func<TSource, TKey>^ keySelector,
	Func<TSource, TElement>^ elementSelector
)

Parameters

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

The sequence to create a ILookup<TKey, TElement> from.

keySelector
Type: System::Func<TSource, TKey>^

A function to extract a key from each element.

elementSelector
Type: System::Func<TSource, TElement>^

A transform function to produce a result element value from each element.

Return Value

Type: System.Linq::ILookup<TKey, TElement>^

A ILookup<TKey, TElement> that contains values of type TElement selected from the input sequence.

Type Parameters

TSource

The type of elements of source.

TKey

The type of the key returned by keySelector.

TElement

The type of the value returned by elementSelector.

Exception Condition
OperationCanceledException

The query was canceled with the token passed in through WithCancellation.

ArgumentNullException

source or keySelector or elementSelector is a null reference (Nothing in Visual Basic).

AggregateException

One or more exceptions occurred during the evaluation of the query.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
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