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Simple linear regression with plot in go with gonum

Very simple linear regression

curl -s //www.lauradhamilton.com/data_files/cricket_chirps_versus_temperature.txt | go run main.go > output.svg
2018/06/13 19:57:59 3.3057614388773593*x+24.966014428303183
package main
import (
"encoding/csv"
"log"
"os"
"strconv"
"gonum.org/v1/gonum/stat"
"gonum.org/v1/plot"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
)
type xy struct {
x []float64
y []float64
}
func (d xy) Len() int {
return len(d.x)
}
func (d xy) XY(i int) (x, y float64) {
x = d.x[i]
y = d.y[i]
return
}
func main() {
r := csv.NewReader(os.Stdin)
records, err := r.ReadAll()
if err != nil {
log.Fatal(err)
}
size := len(records)
data := xy{
x: make([]float64, size),
y: make([]float64, size),
}
for i, v := range records {
if len(v) != 2 {
log.Fatal("Expected two elements")
}
if s, err := strconv.ParseFloat(v[0], 64); err == nil {
data.y[i] = s
}
if s, err := strconv.ParseFloat(v[1], 64); err == nil {
data.x[i] = s
}
}
b, a := stat.LinearRegression(data.x, data.y, nil, false)
log.Printf("%v*x+%v", a, b)
line := plotter.NewFunction(func(x float64) float64 { return a*x + b })
p, err := plot.New()
if err != nil {
log.Panic(err)
}
plotter.DefaultLineStyle.Width = vg.Points(1)
plotter.DefaultGlyphStyle.Radius = vg.Points(2)
scatter, err := plotter.NewScatter(data)
if err != nil {
log.Panic(err)
}
p.Add(scatter, line)
w, err := p.WriterTo(300, 300, "svg")
if err != nil {
log.Panic(err)
}
_, err = w.WriteTo(os.Stdout)
if err != nil {
log.Panic(err)
}
}
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