LagExtensionLagTSource, TResult(IEnumerableTSource, Int32, FuncTSource, TSource, TResult) Method

public static IEnumerable<TResult> Lag<TSource, TResult>(
	this IEnumerable<TSource> source,
	int offset,
	Func<TSource, TSource, TResult> resultSelector
)

<ExtensionAttribute>
Public Shared Function Lag(Of TSource, TResult) ( 
	source As IEnumerable(Of TSource),
	offset As Integer,
	resultSelector As Func(Of TSource, TSource, TResult)
) As IEnumerable(Of TResult)

public:
[ExtensionAttribute]
generic<typename TSource, typename TResult>
static IEnumerable<TResult>^ Lag(
	IEnumerable<TSource>^ source, 
	int offset, 
	Func<TSource, TSource, TResult>^ resultSelector
)

[<ExtensionAttribute>]
static member Lag : 
        source : IEnumerable<'TSource> * 
        offset : int * 
        resultSelector : Func<'TSource, 'TSource, 'TResult> -> IEnumerable<'TResult> 

Parameters

source  IEnumerableTSource

The sequence over which to evaluate lag.

offset  Int32

The offset (expressed as a positive number) by which to lag each value of the sequence.

resultSelector  FuncTSource, TSource, TResult

A projection function which accepts the current and lagged items (in that order) and returns a result.

Type Parameters

TSource

The type of the elements of the source sequence.

TResult

The type of the elements of the result sequence.

Return Value

Usage Note

This operator evaluates in a deferred and streaming manner.

For elements prior to the lag offset, default(T) is used as the lagged value.

Reference