ScanByExtension.ScanBy<TSource, TKey, TState>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TKey, TState>, Func<TState, TKey, TSource, TState>, IEqualityComparer<TKey>) Method

Applies an accumulator function over sequence element keys, returning the keys along with intermediate accumulator states. An additional parameter specifies the comparer to use to compare keys.

Definition

Namespace: MoreLinq.Extensions
Assembly: MoreLinq (in MoreLinq.dll) Version: 3.4.0+b99a6a8cc504caf2d48372fe54a2f8116c59cd0c

C#
public static IEnumerable<KeyValuePair<TKey, TState>> ScanBy<TSource, TKey, TState>(
	this IEnumerable<TSource> source,
	Func<TSource, TKey> keySelector,
	Func<TKey, TState> seedSelector,
	Func<TState, TKey, TSource, TState> accumulator,
	IEqualityComparer<TKey>? comparer
)

VB
<ExtensionAttribute>
Public Shared Function ScanBy(Of TSource, TKey, TState) ( 
	source As IEnumerable(Of TSource),
	keySelector As Func(Of TSource, TKey),
	seedSelector As Func(Of TKey, TState),
	accumulator As Func(Of TState, TKey, TSource, TState),
	comparer As IEqualityComparer(Of TKey)
) As IEnumerable(Of KeyValuePair(Of TKey, TState))

C++
public:
[ExtensionAttribute]
generic<typename TSource, typename TKey, typename TState>
static IEnumerable<KeyValuePair<TKey, TState>>^ ScanBy(
	IEnumerable<TSource>^ source, 
	Func<TSource, TKey>^ keySelector, 
	Func<TKey, TState>^ seedSelector, 
	Func<TState, TKey, TSource, TState>^ accumulator, 
	IEqualityComparer<TKey>^ comparer
)

F#
[<ExtensionAttribute>]
static member ScanBy : 
        source : IEnumerable<'TSource> * 
        keySelector : Func<'TSource, 'TKey> * 
        seedSelector : Func<'TKey, 'TState> * 
        accumulator : Func<'TState, 'TKey, 'TSource, 'TState> * 
        comparer : IEqualityComparer<'TKey> -> IEnumerable<KeyValuePair<'TKey, 'TState>> 

Parameters

source IEnumerable<TSource>: The source sequence.
keySelector Func<TSource, TKey>: A function that returns the key given an element.
seedSelector Func<TKey, TState>: A function to determine the initial value for the accumulator that is invoked once per key encountered.
accumulator Func<TState, TKey, TSource, TState>: An accumulator function invoked for each element.
comparer IEqualityComparer<TKey>: The equality comparer to use to determine whether or not keys are equal. If null, the default equality comparer for TSource is used.

Type Parameters

TSource: Type of the elements of the source sequence.
TKey: The type of the key.
TState: Type of the state.

Return Value

IEnumerable<KeyValuePair<TKey, TState>>
A sequence of keys paired with intermediate accumulator states.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).