Observable.ToLookup<TSource, TKey, TElement> Method (IObservable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)
Creates a lookup from an observable sequence according to a specified key selector function, and an element selector function.
Namespace: System.Reactive.Linq
Assembly: System.Reactive (in System.Reactive.dll)
Syntax
'Declaration
<ExtensionAttribute> _
Public Shared Function ToLookup(Of TSource, TKey, TElement) ( _
source As IObservable(Of TSource), _
keySelector As Func(Of TSource, TKey), _
elementSelector As Func(Of TSource, TElement) _
) As IObservable(Of ILookup(Of TKey, TElement))
'Usage
Dim source As IObservable(Of TSource)
Dim keySelector As Func(Of TSource, TKey)
Dim elementSelector As Func(Of TSource, TElement)
Dim returnValue As IObservable(Of ILookup(Of TKey, TElement))
returnValue = source.ToLookup(keySelector, _
elementSelector)
public static IObservable<ILookup<TKey, TElement>> ToLookup<TSource, TKey, TElement>(
this IObservable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TSource, TElement> elementSelector
)
[ExtensionAttribute]
public:
generic<typename TSource, typename TKey, typename TElement>
static IObservable<ILookup<TKey, TElement>^>^ ToLookup(
IObservable<TSource>^ source,
Func<TSource, TKey>^ keySelector,
Func<TSource, TElement>^ elementSelector
)
static member ToLookup :
source:IObservable<'TSource> *
keySelector:Func<'TSource, 'TKey> *
elementSelector:Func<'TSource, 'TElement> -> IObservable<ILookup<'TKey, 'TElement>>
JScript does not support generic types and methods.
Type Parameters
- TSource
The type of source.
- TKey
The type of key.
- TElement
The type of element.
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.
- elementSelector
Type: System.Func<TSource, TElement>
A transform function to produce a result element value from each element.
Return Value
Type: System.IObservable<ILookup<TKey, TElement>>
A lookup from an observable sequence according to a specified key selector function, and an element selector function.
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 .