RBF Network Diagrams

main.go

package main

import (
	"image"
	"image/color"
	"image/png"
	"math"
	"os"
	"strconv"
)

const (
	Width  = 886
	Height = 687

	C1X = 181
	C1Y = 172

	C2X = 570
	C2Y = 360

	Radius = 140
)

func main() {
	diagrams := []image.Image{rbfDiagram(), rbfSqrtDiagram(), invLinDiagram(), invSquareDiagram(),
		sharpDiagram()}
	for i, dig := range diagrams {
		outFile, _ := os.Create("diagram" + strconv.Itoa(i) + ".png")
		png.Encode(outFile, dig)
		outFile.Close()
	}
}

func rbfDiagram() image.Image {
	return diagram(func(d1, d2 float64) float64 {
		return math.Min(1, (math.Exp(-d1*d1/(Radius*Radius)) + math.Exp(-d2*d2/(Radius*Radius))))
	})
}

func rbfSqrtDiagram() image.Image {
	return diagram(func(d1, d2 float64) float64 {
		return math.Min(1, 1.5*(math.Exp(-d1/Radius)+math.Exp(-d2/Radius)))
	})
}

func invLinDiagram() image.Image {
	return diagram(func(d1, d2 float64) float64 {
		return math.Min(1, 0.5*(Radius/d1+Radius/d2))
	})
}

func invSquareDiagram() image.Image {
	return diagram(func(d1, d2 float64) float64 {
		return math.Min(1, 0.5*(Radius*Radius/(d1*d1)+Radius*Radius/(d2*d2)))
	})
}

func sharpDiagram() image.Image {
	return diagram(func(d1, d2 float64) float64 {
		if d1 < Radius || d2 < Radius {
			return 1
		}
		return 0
	})
}

func diagram(intensityFunc func(d1, d2 float64) float64) image.Image {
	res := image.NewRGBA(image.Rect(0, 0, Width, Height))
	for y := 0; y < Height; y++ {
		for x := 0; x < Width; x++ {
			d1 := dist(C1X, C1Y, x, y)
			d2 := dist(C2X, C2Y, x, y)
			intensity := intensityFunc(d1, d2)
			color := color.RGBA{
				R: uint8(intensity * 0xcc),
				G: uint8((1 - intensity) * 0xcc),
				B: 0x10,
				A: 0xff,
			}
			res.Set(x, y, color)
		}
	}
	return res
}

func dist(x1, y1, x2, y2 int) float64 {
	return math.Sqrt(math.Pow(float64(x1-x2), 2) + math.Pow(float64(y1-y2), 2))
}