Update snippet 'Heatmap Color generation for RGB Colors'

Title

Description

Source code

open System.Drawing

let scaler (sMin,sMax) (vMin,vMax) (v:float) =
    if v < vMin then failwith "out of min range for scaling"
    if v > vMax then failwith "out of max range for scaling"
    (v - vMin) / (vMax - vMin) * (sMax - sMin) + sMin

let createColor (r,g,b) = Color.FromArgb(255, min r 255, min g 255, min b 255)

let interpolate (c1:Color) (c2:Color) (m:float) =
    createColor(
        (1. - m) * float c1.R + float c2.R * m |> int,
        (1. - m) * float c1.G + float c2.G * m |> int,
        (1. - m) * float c1.B + float c2.B * m |> int
    )

let cI (v:float) mn mx (colorRange:Color[]) =
    if v < mn || v > mx then failwithf "value %0.3f should be between min (%0.3f) and max (%0.3f)" v mn mx
    let cindex = scaler (0., float (colorRange.Length - 1)) (mn,mx) v
    let c1 = colorRange.[floor cindex |> int]
    let c2 = colorRange.[ceil cindex |> int]
    let prop = cindex - (floor cindex)
    interpolate c1 c2 prop

//usage:
// cI 0.3 0. 1. [|Color.Blue; Color.Yellow; Color.Red|]