RetroSearch Browse

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://morelinq.github.io/3.0/ref/api/html/M_MoreLinq_MoreEnumerable_PreScan__1.htm below:

MoreEnumerablePreScanTSource Method

Performs a pre-scan (exclusive prefix sum) on a sequence of elements.

Namespace: MoreLinq
Assembly:

MoreLinq (in MoreLinq.dll) Version: 3.0.0

Syntax

public static IEnumerable<TSource> PreScan<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, TSource, TSource> transformation,
	TSource identity
)

<ExtensionAttribute>
Public Shared Function PreScan(Of TSource) ( 
	source As IEnumerable(Of TSource),
	transformation As Func(Of TSource, TSource, TSource),
	identity As TSource
) As IEnumerable(Of TSource)

public:
[ExtensionAttribute]
generic<typename TSource>
static IEnumerable<TSource>^ PreScan(
	IEnumerable<TSource>^ source, 
	Func<TSource, TSource, TSource>^ transformation, 
	TSource identity
)

[<ExtensionAttribute>]
static member PreScan : 
        source : IEnumerable<'TSource> * 
        transformation : Func<'TSource, 'TSource, 'TSource> * 
        identity : 'TSource -> IEnumerable<'TSource>

Parameters

source: Type: System.Collections.GenericIEnumerableTSource
Source sequence
transformation: Type: SystemFuncTSource, TSource, TSource
Transformation operation
identity: Type: TSource
Identity element (see remarks)

Type Parameters

TSource: Type of elements in source sequence

Return Value

Type:

IEnumerableTSource

The scanned sequence

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type

IEnumerableTSource

. When you use instance method syntax to call this method, omit the first parameter. For more information, see

Extension Methods (Visual Basic)

Extension Methods (C# Programming Guide)

Remarks

An exclusive prefix sum returns an equal-length sequence where the N-th element is the sum of the first N-1 input elements (the first element is a special case, it is set to the identity). More generally, the pre-scan allows any commutative binary operation, not just a sum. The inclusive version of PreScan is

ScanTSource(IEnumerableTSource, FuncTSource, TSource, TSource)

. This operator uses deferred execution and streams its result.

Examples

int[] values = { 1, 2, 3, 4 };
var prescan = values.PreScan((a, b) => a + b, 0);
var scan = values.Scan((a, b) => a + b);
var result = values.EquiZip(prescan, ValueTuple.Create);

prescan

will yield

{ 0, 1, 3, 6 }

, while

scan

and

result

will both yield

{ 1, 3, 6, 10 }

. This shows the relationship between the inclusive and exclusive prefix sum.

See Also

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4