ThenByDescending(TSource, TKey) Method (OrderedParallelQuery(TSource), Func(TSource, TKey))

Task Parallel System.Threading

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Performs in parallel a subsequent ordering of the elements in a sequence in descending order, according to a key.

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

Syntax

Visual Basic (Declaration)
Public Shared Function ThenByDescending(Of TSource, TKey) ( _ source As OrderedParallelQuery(Of TSource), _ keySelector As Func(Of TSource, TKey) _ ) As OrderedParallelQuery(Of TSource)

C#
public static OrderedParallelQuery<TSource> ThenByDescending<TSource, TKey>( OrderedParallelQuery<TSource> source, Func<TSource, TKey> keySelector )

Parameters

source: Type: System.Linq..::.OrderedParallelQuery<(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.

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.

Remarks

In contrast to the sequential implementation, this is not a stable sort. See the remarks for OrderBy(ParallelQuery{TSource}, Func{TSource,TKey}) for an approach to implementing a stable sort.

Exceptions

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