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

Returns an observable sequence that contains only distinct elements according to the keySelector.

Namespace:  System.Reactive.Linq
Assembly:  System.Reactive (in System.Reactive.dll)


<ExtensionAttribute> _
Public Shared Function Distinct(Of TSource, TKey) ( _
    source As IObservable(Of TSource), _
    keySelector As Func(Of TSource, TKey), _
    comparer As IEqualityComparer(Of TKey) _
) As IObservable(Of TSource)
Dim source As IObservable(Of TSource)
Dim keySelector As Func(Of TSource, TKey)
Dim comparer As IEqualityComparer(Of TKey)
Dim returnValue As IObservable(Of TSource)

returnValue = source.Distinct(keySelector, _
public static IObservable<TSource> Distinct<TSource, TKey>(
    this IObservable<TSource> source,
    Func<TSource, TKey> keySelector,
    IEqualityComparer<TKey> comparer
generic<typename TSource, typename TKey>
static IObservable<TSource>^ Distinct(
    IObservable<TSource>^ source, 
    Func<TSource, TKey>^ keySelector, 
    IEqualityComparer<TKey>^ comparer
static member Distinct : 
        source:IObservable<'TSource> * 
        keySelector:Func<'TSource, 'TKey> * 
        comparer:IEqualityComparer<'TKey> -> IObservable<'TSource> 
JScript does not support generic types and methods.

Type Parameters

  • TSource
    The type of source.
  • TKey
    The type of key.


  • source
    Type: System.IObservable<TSource>
    An observable sequence to retain distinct elements for.
  • keySelector
    Type: System.Func<TSource, TKey>
    A function to compute the comparison key for each element.

Return Value

Type: System.IObservable<TSource>
An observable sequence only containing the distinct elements, based on a computed key value, from the source sequence.

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


Observable Class

Distinct Overload

System.Reactive.Linq Namespace