Observable

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 .

See Also

Reference

Observable Class

ToLookup Overload

System.Reactive.Linq Namespace

Observable.ToLookup<TSource, TKey> Method (IObservable<TSource>, Func<TSource, TKey>)

Creates a lookup from an observable sequence according to a specified key selector function.

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) _
) As IObservable(Of ILookup(Of TKey, TSource))
'Usage
Dim source As IObservable(Of TSource)
Dim keySelector As Func(Of TSource, TKey)
Dim returnValue As IObservable(Of ILookup(Of TKey, TSource))

returnValue = source.ToLookup(keySelector)
public static IObservable<ILookup<TKey, TSource>> ToLookup<TSource, TKey>(
    this IObservable<TSource> source,
    Func<TSource, TKey> keySelector
)
[ExtensionAttribute]
public:
generic<typename TSource, typename TKey>
static IObservable<ILookup<TKey, TSource>^>^ ToLookup(
    IObservable<TSource>^ source, 
    Func<TSource, TKey>^ keySelector
)
static member ToLookup : 
        source:IObservable<'TSource> * 
        keySelector:Func<'TSource, '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.

Return Value

Type: System.IObservable<ILookup<TKey, TSource>>
A lookup from an observable sequence according to a specified key 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 .

See Also

Reference

Observable Class

ToLookup Overload

System.Reactive.Linq Namespace

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

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 .

See Also

Reference

Observable Class

ToLookup Overload

System.Reactive.Linq Namespace

Observable.ToLookup<TSource, TKey, TElement> Method (IObservable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)

Creates a lookup from an observable sequence according to a specified key selector function, a comparer, 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), _
    comparer As IEqualityComparer(Of TKey) _
) 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 comparer As IEqualityComparer(Of TKey)
Dim returnValue As IObservable(Of ILookup(Of TKey, TElement))

returnValue = source.ToLookup(keySelector, _
    elementSelector, comparer)
public static IObservable<ILookup<TKey, TElement>> ToLookup<TSource, TKey, TElement>(
    this IObservable<TSource> source,
    Func<TSource, TKey> keySelector,
    Func<TSource, TElement> elementSelector,
    IEqualityComparer<TKey> comparer
)
[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, 
    IEqualityComparer<TKey>^ comparer
)
static member ToLookup : 
        source:IObservable<'TSource> * 
        keySelector:Func<'TSource, 'TKey> * 
        elementSelector:Func<'TSource, 'TElement> * 
        comparer:IEqualityComparer<'TKey> -> 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

Return Value

Type: System.IObservable<ILookup<TKey, TElement>>
A lookup from an observable sequence according to a specified key selector function, a comparer, 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 .

See Also

Reference

Observable Class

ToLookup Overload

System.Reactive.Linq Namespace