chart

chart -- chart package using the fync canvas library

The chart library works by reading data into a ChartBox structure, and then composing elements as needed. Elements (chart types: linechart, bar, column, scatter, attributes: axes, titles, and frames) are arranged within a scalable area defined by a top, bottom, left, right.

	// Open data files
	sr, err := os.Open("sin.d")
	if err != nil {
		return err
	}
	cr, err := os.Open("cos.d")
	if err != nil {
		return err
	}

	// Read in the data
	sine, err := chart.DataRead(sr)
	if err != nil {
		return err
	}
	cosine, err := chart.DataRead(cr)
	if err != nil {
		return err
	}
	sr.Close()
	cr.Close()


	// Compose elements
	sine.Zerobased, cosine.Zerobased = false, false

	// composite two charts
	cosine.Frame(canvas, 5)
	cosine.Label(canvas, 1.5, 10)
	cosine.YAxis(canvas, 1.2, -1.0, 1.0, 1.0, "%0.2f", true)
	cosine.Color = color.RGBA{0, 128, 0, 255}
	sine.Color = color.RGBA{128, 0, 0, 255}
	cosine.Scatter(canvas, 0.75)
	sine.Scatter(canvas, 0.75)

	// two charts side by side
	sine.Left = 10
	sine.Right = sine.Left + 40
	sine.Top, cosine.Top = 30, 30
	sine.Bottom, cosine.Bottom = 10, 10

	sine.CTitle(canvas, 2, 2)
	sine.Frame(canvas, 5)
	sine.Scatter(canvas, 0.5)

	offset := 45.0
	cosine.Left = sine.Left + offset
	cosine.Right = sine.Right + offset

	cosine.CTitle(canvas, 2, 2)
	cosine.Frame(canvas, 5)
	cosine.Scatter(canvas, 0.5)