Add an example of pretty ticks on Y axis

_examples/pretty_ticks/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/wcharczuk/go-chart"
+)
+
+func drawChart(res http.ResponseWriter, req *http.Request) {
+	sbc := chart.BarChart{
+		Title:      "Test Bar Chart",
+		TitleStyle: chart.StyleShow(),
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 40,
+			},
+		},
+		Height:   512,
+		BarWidth: 60,
+		XAxis:    chart.StyleShow(),
+		YAxis: chart.YAxis{
+			Style:             chart.StyleShow(),
+			EnablePrettyTicks: true,
+		},
+		Bars: []chart.Value{
+			{Value: 5.25, Label: "Blue"},
+			{Value: 4.88, Label: "Green"},
+			{Value: 4.74, Label: "Gray"},
+			{Value: 3.22, Label: "Orange"},
+			{Value: 3, Label: "Test"},
+			{Value: 2.27, Label: "??"},
+			{Value: 1, Label: "!!"},
+		},
+	}
+
+	res.Header().Set("Content-Type", "image/png")
+	err := sbc.Render(chart.PNG, res)
+	if err != nil {
+		fmt.Printf("Error rendering chart: %v\n", err)
+	}
+}
+
+func port() string {
+	if len(os.Getenv("PORT")) > 0 {
+		return os.Getenv("PORT")
+	}
+	return "8080"
+}
+
+func main() {
+	listenPort := fmt.Sprintf(":%s", port())
+	fmt.Printf("Listening on %s\n", listenPort)
+	http.HandleFunc("/", drawChart)
+	log.Fatal(http.ListenAndServe(listenPort, nil))
+}