Qbservable.ToLookup<TSource, TKey, TElement> Method (IQbservable<TSource>, Expression<Func<TSource, TKey>>, Expression<Func<TSource, TElement>>)
Creates a lookup from a queryable observable sequence according to a specified key selector function, and an element selector function.
Namespace: System.Reactive.Linq
Assembly: System.Reactive.Providers (in System.Reactive.Providers.dll)
Syntax
'Declaration
<ExtensionAttribute> _
Public Shared Function ToLookup(Of TSource, TKey, TElement) ( _
source As IQbservable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
elementSelector As Expression(Of Func(Of TSource, TElement)) _
) As IQbservable(Of ILookup(Of TKey, TElement))
'Usage
Dim source As IQbservable(Of TSource)
Dim keySelector As Expression(Of Func(Of TSource, TKey))
Dim elementSelector As Expression(Of Func(Of TSource, TElement))
Dim returnValue As IQbservable(Of ILookup(Of TKey, TElement))
returnValue = source.ToLookup(keySelector, _
elementSelector)
public static IQbservable<ILookup<TKey, TElement>> ToLookup<TSource, TKey, TElement>(
this IQbservable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TSource, TElement>> elementSelector
)
[ExtensionAttribute]
public:
generic<typename TSource, typename TKey, typename TElement>
static IQbservable<ILookup<TKey, TElement>^>^ ToLookup(
IQbservable<TSource>^ source,
Expression<Func<TSource, TKey>^>^ keySelector,
Expression<Func<TSource, TElement>^>^ elementSelector
)
static member ToLookup :
source:IQbservable<'TSource> *
keySelector:Expression<Func<'TSource, 'TKey>> *
elementSelector:Expression<Func<'TSource, 'TElement>> -> IQbservable<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.Reactive.Linq.IQbservable<TSource>
A queryable observable sequence to create a lookup for.
- keySelector
Type: System.Linq.Expressions.Expression<Func<TSource, TKey>>
A function to extract a key from each element.
- elementSelector
Type: System.Linq.Expressions.Expression<Func<TSource, TElement>>
A transform function to produce a result element value from each element.
Return Value
Type: System.Reactive.Linq.IQbservable<ILookup<TKey, TElement>>
A lookup from a queryable 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 IQbservable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see or .