normal.go

package main

import (
	"fmt"
	"math"
	"math/rand"
	"time"
)

type Series []float64

func main() {

	// s := Series{23.6, 76.1, 89.0, 12.8}
	// sample := Series{206.0, 76.0, -224.0, 36.0, -94.0}
	// sample := Series{26.0, 33.0, 65.0, 28.0, 34.0, 55.0, 25.0, 44.0, 50.0, 36.0, 26.0, 37.0, 43.0, 62.0, 35.0, 38.0, 45.0, 32.0, 28.0, 34.0}

	// fmt.Println(sample.Mean())
	// fmt.Println(sample.Len())
	// fmt.Println(sample.StdDev())
	// fmt.Println(sample.Z(65))

	scores := Series{}
	rand.Seed(time.Now().Unix())
	for i := 0; i < 100000; i++ {
		scores = append(scores, Round(rand.NormFloat64(), 1))
	}

	// freq := map[float64]int{}
	// for _, z := range scores {
	// 	freq[z] += 1
	// }

	// fmt.Println(scores.Freq())

	// z := Round((rand.Float64()*6.)-3., 1)
	z := Round(rand.NormFloat64(), 1)
	fmt.Println(z)

	hist := scores.Freq()
	for x := -3.0; x <= 3.0; x += 0.1 {
		v := int(hist[Round(x, 1)] / 100)
		v2 := int(hist[Round(x+0.1, 1)] / 100)

		s := ""

		for j := 0; j < v; j++ {
			if Round(x, 1) <= z {
				s += "|_"
			} else {
				s += "  "
			}
		}
		fmt.Printf("\t%0.1f\t%s|\n", x, s)

		s = ""
		for j := 0; j < v2; j++ {
			if Round(x, 1) < z {
				s += " _"
			} else {
				s += " "
			}
		}

		fmt.Printf("\t   \t%s\n", s)

		// if Round(x, 1) == z {
		// 	fmt.Printf("\t%0.1f\t%sO\n", x, s)

		// } else {

		// }

	}

}

func (s Series) Mean() float64 {
	return s.Sum() / s.Len()
}

func (s Series) Sum() (total float64) {
	for _, f := range s {
		total += f
	}
	return
}

func (s Series) Len() float64 {
	return float64(len(s))
}

func (s Series) SumSquares() (total float64) {
	mean := s.Mean()
	for _, f := range s {
		total += math.Pow((f - mean), 2)
	}
	return
}

func (s Series) StdDev() float64 {
	return math.Sqrt(s.SumSquares() / (s.Len()))
}

func (s Series) Z(x float64) float64 {
	return (x - s.Mean()) / s.StdDev()
}

func Round(f float64, places int) float64 {
	shift := math.Pow(10, float64(places))
	f = f * shift
	return math.Floor(f+.5) / shift
}

func (s Series) Freq() map[float64]int {
	freq := map[float64]int{}
	for _, z := range s {
		freq[z] += 1
	}

	return freq
}