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Observable.GroupBy(TSource, TKey, TElement) Method (IObservable(TSource), Func(TSource, TKey), Func(TSource, TElement), IEqualityComparer(TKey))

Groups the elements of an observable sequence according to a specified key selector function and comparer and selects the resulting elements by using a specified function.

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

static member GroupBy : 
        source:IObservable<'TSource> * 
        keySelector:Func<'TSource, 'TKey> * 
        elementSelector:Func<'TSource, 'TElement> * 
        comparer:IEqualityComparer<'TKey> -> IObservable<IGroupedObservable<'TKey, 'TElement>> 

Type Parameters

TSource

The type source.

TKey

The type key.

TElement

The type element.

Parameters

source
Type: System.IObservable(TSource)
An observable sequence whose elements to group.
keySelector
Type: System.Func(TSource, TKey)
A function to extract the key for each element.
elementSelector
Type: System.Func(TSource, TElement)
A function to map each source element to an element in an observable group.
comparer
Type: System.Collections.Generic.IEqualityComparer(TKey)
An equality comparer to compare keys with.

Return Value

Type: System.IObservable(IGroupedObservable(TKey, TElement))
A sequence of observable groups, each of which corresponds to a unique key value, containing all elements that share that same key value.

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 https://msdn.microsoft.com/en-us/library/bb384936(v=vs.103).aspx or https://msdn.microsoft.com/en-us/library/bb383977(v=vs.103).aspx.
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