Day 29: Review and Gonum Plot

[mchirico]

Video https://github.com/gonum/plot

For answer, see PR. https://github.com/mchirico/zDaily/blob/c387da94e077e99412fa5d727e59f1dd232b1e58/main.go#L11

Note: go-echarts might be a better package

[tacomonkautobot[bot]]

mchirico, Thanks for opening this issue!

[ZoeChiri]

what do I submit??

[mchirico]

@ZoeChiri I was looking for a general solution for plotting graphs for multiple size and number of vectors. As it turns out, it's not that easy... kind of interesting... Ref: https://github.com/mchirico/gplot

package plot

import (
    "fmt"
    "gonum.org/v1/plot"
    "gonum.org/v1/plot/plotter"
    "gonum.org/v1/plot/plotutil"
    "gonum.org/v1/plot/vg"
    "image/color"
)

func Convert(v []float64) plotter.Values {
    c := make(plotter.Values, len(v))
    c = v
    return c
}

func Bar(group plotter.Values, w vg.Length, i int) *plotter.BarChart {
    bar, err := plotter.NewBarChart(group, vg.Points(10))
    if err != nil {
        panic(err)
    }
    bar.LineStyle.Width = vg.Length(0)
    bar.Color = plotutil.Color(i)
    bar.Offset = w
    return bar
}

func CalcOffset(n int)  []vg.Length {
    spread := vg.Length(25)
    steps := spread/vg.Length(n)

    v := []vg.Length{}
    for  i := -spread;i <= spread; i+= 2*steps {
        v = append(v,i)
    }
    return v
}

func Draw(v ...[]float64) {

    group := []plotter.Values{}
    for i,_ := range v {
        group = append(group,v[i])
    }

    p, err := plot.New()
    if err != nil {
        panic(err)
    }

    p.BackgroundColor = color.RGBA{R: 25, B: 20, G: 25, A: 40}

    p.Title.Text = "Bar chart"
    p.Y.Label.Text = "Heights"

    offset := CalcOffset(len(group))
    bars := []plot.Plotter{}

    for i,_ := range group {
        bars = append(bars,Bar(group[i],offset[i],i ))

    }

    p.Add(bars...)
    names := []string{}
    names2 := []string{}
    for i,_ := range bars {
        names = append(names,fmt.Sprintf("Group %d",i) )
        names2 = append(names2,fmt.Sprintf("Set %d",i) )
        p.Legend.Add(names[i], bars[i].(plot.Thumbnailer))
    }

    p.Legend.Top = true
    p.NominalX(names2...)

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