Observable.ToLookup<TSource, TKey> Method (IObservable<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)
Creates a lookup from an observable sequence according to a specified key selector function, and a comparer.
Namespace: System.Reactive.Linq
Assembly: System.Reactive (in System.Reactive.dll)
Syntax
'Declaration
<ExtensionAttribute> _
Public Shared Function ToLookup(Of TSource, TKey) ( _
source As IObservable(Of TSource), _
keySelector As Func(Of TSource, TKey), _
comparer As IEqualityComparer(Of TKey) _
) As IObservable(Of ILookup(Of TKey, TSource))
'Usage
Dim source As IObservable(Of TSource)
Dim keySelector As Func(Of TSource, TKey)
Dim comparer As IEqualityComparer(Of TKey)
Dim returnValue As IObservable(Of ILookup(Of TKey, TSource))
returnValue = source.ToLookup(keySelector, _
comparer)
public static IObservable<ILookup<TKey, TSource>> ToLookup<TSource, TKey>(
this IObservable<TSource> source,
Func<TSource, TKey> keySelector,
IEqualityComparer<TKey> comparer
)
[ExtensionAttribute]
public:
generic<typename TSource, typename TKey>
static IObservable<ILookup<TKey, TSource>^>^ ToLookup(
IObservable<TSource>^ source,
Func<TSource, TKey>^ keySelector,
IEqualityComparer<TKey>^ comparer
)
static member ToLookup :
source:IObservable<'TSource> *
keySelector:Func<'TSource, 'TKey> *
comparer:IEqualityComparer<'TKey> -> IObservable<ILookup<'TKey, 'TSource>>
JScript does not support generic types and methods.
Type Parameters
- TSource
The type of source.
- TKey
The type of key.
Parameters
- source
Type: System.IObservable<TSource>
An observable sequence to create a lookup for.
- keySelector
Type: System.Func<TSource, TKey>
A function to extract a key from each element.
- comparer
Type: System.Collections.Generic.IEqualityComparer<TKey>
An equality comparer to compare keys.
Return Value
Type: System.IObservable<ILookup<TKey, TSource>>
A lookup from an observable sequence according to a specified key selector function, and a comparer.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IObservable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see or .