go-chart/_examples/twoaxis/main.go

package main

import (
	"fmt"
	"net/http"

	chart "github.com/wcharczuk/go-chart"
)

func drawChart(res http.ResponseWriter, req *http.Request) {

	/*
	   In this example we add a second series, and assign it to the secondary y axis, giving that series it's own range.

	   We also enable all of the axes by setting the `Show` propery of their respective styles to `true`.
	*/

	graph := chart.Chart{
		XAxis: chart.XAxis{
			Style:        chart.StyleShow(), //enables / displays the x-axis
			TickPosition: chart.TickPositionBetweenTicks,
			ValueFormatter: func(v interface{}) string {
				typed := v.(float64)
				typedDate := chart.TimeFromFloat64(typed)
				return fmt.Sprintf("%d-%d\n%d", typedDate.Month(), typedDate.Day(), typedDate.Year())
			},
		},
		YAxis: chart.YAxis{
			Style: chart.StyleShow(), //enables / displays the y-axis
		},
		YAxisSecondary: chart.YAxis{
			Style: chart.StyleShow(), //enables / displays the secondary y-axis
		},
		Series: []chart.Series{
			chart.ContinuousSeries{
				XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
				YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
			},
			chart.ContinuousSeries{
				YAxis:   chart.YAxisSecondary,
				XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
				YValues: []float64{50.0, 40.0, 30.0, 20.0, 10.0},
			},
		},
	}

	res.Header().Set("Content-Type", "image/png")
	graph.Render(chart.PNG, res)
}

func main() {
	http.HandleFunc("/", drawChart)
	http.ListenAndServe(":8080", nil)
}