[BUG] Padding.pad drops a data element, and the end padding is backwards about fsharp.stats

[bvenn]

Thanks for reporting!🚀
I've traced down the issue to the following two lines:

The Array.rev must be removed at:

FSharp.Stats/src/FSharp.Stats/Signal/Padding.fs

Lines 140 to 144 in 3d6a220

	Array.init borderpadding (fun i ->
	let paddX = addToXValue maxX ((float i + 1.) * minDistance)
	let paddY = 0.
	paddX,paddY)
	|> Array.rev

The last point has to be integrated here:

FSharp.Stats/src/FSharp.Stats/Signal/Padding.fs

Lines 164 to 167 in 3d6a220

	if i = n-1 then
	acc
	|> List.rev
	|> List.concat

After these modifications the result looks as follows:

//#r "nuget:FSharp.Stats"
#r @"C:\Users\bvenn\source\repos\FSharp.Stats\src\FSharp.Stats\bin\Release\netstandard2.0\FSharp.Stats.dll"
#r "nuget:Expecto"
#r "nuget: Plotly.NET"

open Plotly.NET

open System
open FSharp.Stats.Signal
open Expecto

let dataLength = 20
let padding = 10

let data =
    Array.init dataLength (
        fun i ->
            (3.0 + float i, 7.0 - float i)
    )


let expectLeadIn  = Array.init padding (fun i -> (3.0 - float (padding-i), 0.0))
let expectLeadOut = Array.init padding (fun i -> (3.0 + float (dataLength + i), 0.0))
let expectedPadded = Array.concat [expectLeadIn; data; expectLeadOut]

let padded = 
    Padding.pad data 1.0 Double.PositiveInfinity (-) (+) padding Padding.BorderPaddingMethod.Zero Padding.InternalPaddingMethod.NaN Padding.HugeGapPaddingMethod.NaN

let indices = Array.init padded.Length (fun x -> string x)

[
Chart.Point(data,Name="raw data")           |> Chart.withMarkerStyle (Size=10)
Chart.Point(expectedPadded,Name="expected") |> Chart.withMarkerStyle (Size=8)
Chart.Point(padded,Name="actual",MultiText=indices,TextPosition=StyleParam.TextPosition.TopRight)           |> Chart.withMarkerStyle (Size=6)
]
|> Chart.combine
|> Chart.show

@marklam, if it is ok for you I would integrate your tests into the test project. Of course you can add them yourself and file a PR if you want to.

[marklam]

@bvenn I'm more than happy for you to integrate those tests. Thanks for responding so quickly!

[bvenn]

closed by 153d95e