Qbservable.GroupBy(Of TSource, TKey, TElement) Method (IQbservable(Of TSource), Expression(Of Func(Of TSource, TKey)), Expression(Of Func(Of TSource, TElement)), IEqualityComparer(Of TKey))

Groups the elements of a queryable 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.Providers (in System.Reactive.Providers.dll)

<ExtensionAttribute> _
Public Shared Function GroupBy(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)), _
	comparer As IEqualityComparer(Of TKey) _
) As IQbservable(Of IGroupedObservable(Of TKey, TElement))
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 comparer As IEqualityComparer(Of TKey)
Dim returnValue As IQbservable(Of IGroupedObservable(Of TKey, TElement))

returnValue = source.GroupBy(keySelector, _
	elementSelector, comparer)

Type Parameters


The type source.


The type key.


The type element.


Type: System.Reactive.Linq.IQbservable(Of TSource)
A queryable observable sequence whose elements to group.
Type: System.Linq.Expressions.Expression(Of Func(Of TSource, TKey))
A function to extract the key for each element.
Type: System.Linq.Expressions.Expression(Of Func(Of TSource, TElement))
A function to map each source element to an element in an observable group.
Type: System.Collections.Generic.IEqualityComparer(Of TKey)
An equality comparer to compare keys with.

Return Value

Type: System.Reactive.Linq.IQbservable(Of IGroupedObservable(Of TKey, TElement))
A sequence of queryable 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 IQbservable(Of 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.