func plotTableSizes(sess *r.Session) {
sizes := []float64{}
for _, t := range tables {
sizes = append(sizes, float64(averageDocumentSize(sess, t)))
}
p, _ := plot.New()
p.Title.Text = "Average document sizes"
p.Y.Label.Text = "Size in bytes"
w := vg.Points(20)
bars, _ := plotter.NewBarChart(plotter.Values(sizes), w)
bars.Color = plotutil.Color(0)
bars.LineStyle.Width = vg.Length(0)
p.Add(bars)
p.NominalX(tables...)
p.Save(6*vg.Inch, 6*vg.Inch, "avg_doc_sizes.png")
}
func main() {
suppressWarnings := flag.Bool("suppress", false, "suppress warnings in the input data")
doPlot := flag.Bool("plot", false, "plot a histogram and the standard normal distribution")
flag.Parse()
c := csv.NewReader(bufio.NewReader(os.Stdin))
headers, err := c.Read()
if err != nil {
log.Fatalf("Could not read header: %v", err)
}
stats := make([]*columnStatistic, 0, len(headers))
for _, name := range headers {
stats = append(stats, &columnStatistic{
name: name,
})
}
line := 0
for {
line++
columns, err := c.Read()
if err != nil {
if err == io.EOF {
// Print statistics
w := tabwriter.NewWriter(os.Stdout, 5, 8, 1, '\t', tabwriter.AlignRight)
fmt.Fprint(w, "\n\tmin\tmax\tmean\tstddev\n")
for _, s := range stats {
mean, stddev := stat.MeanStdDev(s.obsv, nil)
fmt.Fprintf(w, "%s\t%f\t%f\t%f\t%f\n", s.name, s.min, s.max, mean, stddev)
}
w.Flush()
if *doPlot {
for _, s := range stats {
mean, stddev := stat.MeanStdDev(s.obsv, nil)
p, err := plot.New()
if err != nil {
panic(err)
}
p.X.Min = s.min - 1.5*stddev
p.X.Max = s.max + 1.5*stddev
p.Title.Text = fmt.Sprintf("Histogram for %s", s.name)
h, err := plotter.NewHist(plotter.Values(s.obsv), 16)
if err != nil {
panic(err)
}
h.Normalize(1)
p.Add(h)
norm := plotter.NewFunction(func(x float64) float64 {
return 1.0 / (stddev * math.Sqrt(2*math.Pi)) * math.Exp(-((x-mean)*(x-mean))/(2*stddev*stddev))
})
norm.Samples = int(p.X.Max-p.X.Min) + 100
norm.Color = color.RGBA{R: 255, A: 255}
norm.Width = vg.Points(2)
p.Add(norm)
// Save the plot to a PNG file.
if err := p.Save(4*vg.Inch, 4*vg.Inch, fmt.Sprintf("histogram-%s.png", s.name)); err != nil {
log.Fatal(err)
}
}
}
return
}
if !*suppressWarnings {
fmt.Fprintf(os.Stderr, "Could not parse line (line %d, '%s'): %v\n", line, columns, err)
}
continue
}
for i, data := range columns {
s := stats[i]
if s.typ == unknown {
// Determine the column's data type
_, err := strconv.ParseFloat(data, 64)
switch {
case err == nil:
// Is numeric
s.typ = numeric
case err != nil:
s.typ = text
}
}
var f float64
switch s.typ {
case numeric:
f, err = strconv.ParseFloat(data, 64)
if err != nil {
if !*suppressWarnings {
fmt.Fprintf(os.Stderr, "Could not parse numeric value (line %d, '%s'): %v\n", line, data, err)
}
continue
}
if math.IsNaN(f) {
if !*suppressWarnings {
fmt.Fprintf(os.Stderr, "Could not parse numeric value (line %d, '%s'): is not a number\n", line, data)
}
continue
}
if math.IsInf(f, 0) {
if !*suppressWarnings {
fmt.Fprintf(os.Stderr, "Could not parse numeric value (line %d, '%s'): infinity\n", line, data)
}
continue
}
case text:
// we take the text length as the according metric
f = float64(len(data))
default:
panic("unknown data type")
}
s.obsv = append(s.obsv, f)
if f < s.min {
s.min = f
}
if f > s.max {
s.max = f
}
}
}
}
