Histogram using Golang

histogram.go

// Cleuton Sampaio
package main

import (
	"fmt"
	"math"
	"math/rand"

	"github.com/emirpasic/gods/utils"
	"gonum.org/v1/plot"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/plotutil"
	"gonum.org/v1/plot/vg"

	"github.com/emirpasic/gods/maps/treemap"
)

func randomArray(len int) []float64 {
	a := make([]float64, len)
	for i := 0; i <= len-1; i++ {
		a[i] = math.Round(rand.Float64()*1000) / 100
	}
	return a
}

func main() {
	rand.Seed(42)
	m := treemap.NewWith(utils.Float64Comparator)
	m.Put(0.0, 0)
	m.Put(2.0, 0)
	m.Put(4.0, 0)
	m.Put(6.0, 0)
	m.Put(8.0, 0)
	averages := randomArray(100)
	for _, element := range averages {
		key, value := m.Floor(element)
		v := 1 + value.(int)
		fmt.Println(" Element ", element, " Key ", key, " value ", value)
		m.Put(key, v)
	}
	fmt.Println(m)
	orig := m.Values()
	floatV := []float64{}
	for _, v := range orig {
		floatV = append(floatV, float64(v.(int)))
	}
	groupA := plotter.Values(floatV)
	p, err := plot.New()
	if err != nil {
		panic(err)
	}
	p.Title.Text = "Histogram"
	p.Y.Label.Text = "Count"

	w := vg.Points(20)
	barsA, err := plotter.NewBarChart(groupA, w)
	if err != nil {
		panic(err)
	}
	barsA.LineStyle.Width = vg.Length(0)
	barsA.Color = plotutil.Color(0)
	barsA.Offset = -w
	p.Add(barsA)
	p.Legend.Top = true
	p.NominalX("<=2", "<=4", "<=6", "<=8", ">8")

	if err := p.Save(5*vg.Inch, 3*vg.Inch, "./histogram.png"); err != nil {
		panic(err)
	}

}