Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

examples/twoaxis/main.go

@@ -0,0 +1,45 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/wcharczuk/go-chart/v2"
+)
+
+func main() {
+
+	/*
+	   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{
+			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())
+			},
+		},
+		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},
+			},
+		},
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}