ParallelEnumerable.ToLookup<TSource, TKey> Method (ParallelQuery<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)
.NET Framework (current version)
Creates an ILookup<TKey, TElement> from a ParallelQuery<TSource> according to a specified key selector function and key comparer.
Assembly: System.Core (in System.Core.dll)
public static ILookup<TKey, TSource> ToLookup<TSource, TKey>( this ParallelQuery<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer )
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.
- comparer
-
Type:
System.Collections.Generic.IEqualityComparer<TKey>
An IEqualityComparer<T> to compare keys.
Return Value
Type: System.Linq.ILookup<TKey, TSource>A ILookup<TKey, TElement> that contains keys and values.
Type Parameters
- TSource
The type of elements of source.
- TKey
The type of the key returned by keySelector.
| Exception | Condition |
|---|---|
| OperationCanceledException | The query was canceled with the token passed in through WithCancellation. |
| ArgumentNullException | source or keySelector or 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
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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