GroupBy(TSource, TKey) Method (ParallelQuery(TSource), Func(TSource, TKey), IEqualityComparer(TKey))

Task Parallel System.Threading

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Groups in parallel the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer.

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

Syntax

Visual Basic (Declaration)
Public Shared Function GroupBy(Of TSource, TKey) ( _ source As ParallelQuery(Of TSource), _ keySelector As Func(Of TSource, TKey), _ comparer As IEqualityComparer(Of TKey) _ ) As ParallelQuery(Of IGrouping(Of TKey, TSource))

Visual Basic (Declaration)

Public Shared Function GroupBy(Of TSource, TKey) ( _
	source As ParallelQuery(Of TSource), _
	keySelector As Func(Of TSource, TKey), _
	comparer As IEqualityComparer(Of TKey) _
) As ParallelQuery(Of IGrouping(Of TKey, TSource))

C#
public static ParallelQuery<IGrouping<TKey, TSource>> GroupBy<TSource, TKey>( ParallelQuery<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer )

Parameters

source: Type: System.Linq..::.ParallelQuery<(Of <(TSource>)>)
An OrderedParallelQuery{TSource} than contains elements to sort.

keySelector: Type: System..::.Func<(Of <(TSource, TKey>)>)
A function to extract a key from an element.

comparer: Type: System.Collections.Generic..::.IEqualityComparer<(Of <(TKey>)>)
An IComparer{TSource} to compare keys.

Type Parameters

TSource: The type of elements of source.
TKey: The type of the key returned by keySelector>.

Return Value

An OrderedParallelQuery{TSource} whose elements are sorted descending according to a key.

Exceptions

Exception	Condition
System..::.ArgumentNullException	source or keySelector is a null reference (Nothing in Visual Basic).