very wide horizontal svg render is missing the time axis with a variable set width

[jeffwillette]

sorry for the confusing title, but I have a strange situation where I am setting the width by the number of data points I have...

graph.Width = (len(data.Time) / 30) * 4

I have 30 reading from an accelerometer every second so I am making each second of data 4 pixels wide (I believe)

Here is the code that I am using:

func main() {
	fileName := os.Args[1]
	readFile := fmt.Sprintf("./%s", fileName)
	outFile := fmt.Sprintf("./%s.svg", strings.Split(fileName, ".")[0])
	fmt.Println(readFile, outFile)
	data, err := readAccelerometerFile(readFile)
	var x []float64
	for i := range data.Time {
		//fmt.Println(data.Time[i], data.Time[i].Unix())
		x = append(x, float64(data.Time[i].UnixNano()))
	}
	fmt.Println(len(data.X), len(data.Time))

	graph := chart.Chart{
		XAxis: chart.XAxis{
			Style: chart.Style{
				Show: true,
			},
			ValueFormatter: func(v interface{}) string {
				typed := v.(float64)
				typedDate := util.Time.FromFloat64(typed)
				return fmt.Sprintf("%d:%d:%d", typedDate.Hour(), typedDate.Minute(), typedDate.Second())
			},
		},
		YAxis: chart.YAxis{
			Style: chart.Style{
				Show: true,
			},
			GridMajorStyle: chart.Style{
				Show:        true,
				StrokeColor: chart.ColorAlternateLightGray,
				StrokeWidth: 1.0,
			},
			GridLines: []chart.GridLine{
				chart.GridLine{Value: -6.0},
				chart.GridLine{Value: -4.0},
				chart.GridLine{Value: -2.0},
				chart.GridLine{Value: 2.0},
				chart.GridLine{Value: 4.0},
				chart.GridLine{Value: 6.0},
			},
		},
		Series: []chart.Series{
			chart.ContinuousSeries{ // x axis acceleration
				XValues: x,
				YValues: data.Z,
			},
			chart.ContinuousSeries{ // x axis acceleration
				XValues: x,
				YValues: data.X,
			},
			chart.ContinuousSeries{ // x axis acceleration
				XValues: x,
				YValues: data.Y,
			},
		},
	}

	graph.Width = (len(data.Time) / 30) * 4
	buffer := bytes.NewBuffer([]byte{})
	err = graph.Render(chart.SVG, buffer)
	if err != nil {
		fmt.Println(err)
	}

	err = ioutil.WriteFile(outFile, buffer.Bytes(), 0644)
	if err != nil {
		fmt.Println(err)
	}
}

If youll notice, I have printed the length to verify that the length of the Y-axis data is the same as the X(time) axis data. it prints 482980 482980 so they are the same.

If I use a pixel width per second of 4 (like in the example above) everything comes out ok, like this example file: (sorry, GH will not accept the file, and it is about 15mb)

http://s000.tinyupload.com/index.php?file_id=25360982963139220109

but if I change the number to 8 or 16 which is where I want it, the time axis stops at a certain point.

http://s000.tinyupload.com/index.php?file_id=02149796522295593801

[jeffwillette]

this is width set to 4 pixels per second

this is set to 8 pixels per second

the end of the 8 pixels per second chart still has the correct end time

[jeffwillette]

The fix doesn't fix the underlying issue, but it would have been much easier for me to find the cause if the proper variable was used from defaults.go

[wcharczuk]

ack, good catch