ParallelEnumerable::GroupBy<TSource, TKey, TElement> Method (ParallelQuery<TSource>^, Func<TSource, TKey>^, Func<TSource, TElement>^)
Groups in parallel the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function.
Assembly: System.Core (in System.Core.dll)
public: generic<typename TSource, typename TKey, typename TElement> [ExtensionAttribute] static ParallelQuery<IGrouping<TKey, TElement>^>^ GroupBy( ParallelQuery<TSource>^ source, Func<TSource, TKey>^ keySelector, Func<TSource, TElement>^ elementSelector )
Parameters
- source
-
Type:
System.Linq::ParallelQuery<TSource>^
An OrderedParallelQuery<TSource> that contains elements to sort.
- keySelector
-
Type:
System::Func<TSource, TKey>^
A function to extract a key from an element.
- elementSelector
-
Type:
System::Func<TSource, TElement>^
A function to map each source element to an element in an IGrouping<TKey, TElement>.
Return Value
Type: System.Linq::ParallelQuery<IGrouping<TKey, TElement>^>^A sequence of groups that are sorted descending according to TKey.
Type Parameters
- TSource
The type of elements of source.
- TKey
The type of the key returned by keySelector.
- TElement
The type of the elements in the IGrouping<TKey, TElement>.
| Exception | Condition |
|---|---|
| OperationCanceledException | The query was canceled with the token passed in through WithCancellation. |
| ArgumentNullException | source or action is a null reference (Nothing in Visual Basic). |
| AggregateException | One or more exceptions occurred during the evaluation of the query. |
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1