Example #1
0
func LogisticRegression(c *gopark.Context) {
	type dataPoint struct {
		x gopark.Vector
		y float64
	}

	points := c.TextFile("points.txt").Map(func(line interface{}) interface{} {
		vs := strings.Fields(line.(string))
		vector := make(gopark.Vector, len(vs)-1)
		for i := 0; i < len(vs)-1; i++ {
			vector[i], _ = strconv.ParseFloat(vs[i], 64)
		}
		y, _ := strconv.ParseFloat(vs[len(vs)-1], 64)
		return &dataPoint{vector, y}
	}).Cache()

	hx := func(w, x gopark.Vector, y float64) float64 {
		return 1/(1+math.Exp(-1*w.Dot(x))) - y
	}
	var w gopark.Vector = []float64{1, -10}[:]
	for i := 0; i < 10; i++ {
		gradient := points.Map(func(x interface{}) interface{} {
			p := x.(*dataPoint)
			return p.x.Multiply(-1 * hx(w, p.x, p.y))
		}).Reduce(func(x, y interface{}) interface{} {
			return x.(gopark.Vector).Plus(y.(gopark.Vector))
		}).(gopark.Vector)
		w = w.Minus(gradient)
	}
	fmt.Println("Final Weights:", w)
}
Example #2
0
func CloseCenter(p gopark.Vector, centers []gopark.Vector) int {
	minDist := p.EulaDistance(centers[0])
	minIndex := 0
	for i := 1; i < len(centers); i++ {
		dist := p.EulaDistance(centers[i])
		if dist < minDist {
			minDist = dist
			minIndex = i
		}
	}
	return minIndex
}