fixing an issue with forcing the secondary y axis on when there were no series mapped to it.

examples/stock_analysis.go/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/wcharczuk/go-chart"
+)
+
+func drawChart(res http.ResponseWriter, req *http.Request) {
+	xvalues, yvalues := getMockChartData()
+
+	priceSeries := chart.TimeSeries{
+		XValues: xvalues,
+		YValues: yvalues,
+	}
+
+	graph := chart.Chart{
+		Series: []chart.Series{
+			priceSeries,
+		},
+	}
+
+	res.Header().Set("Content-Type", "image/svg+xml")
+	graph.Render(chart.SVG, res)
+}
+
+func main() {
+	http.HandleFunc("/", drawChart)
+	http.ListenAndServe(":8080", nil)
+}