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// Copyright ©2015 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package plotter_test
import (
"image/color"
"log"
"math"
"golang.org/x/exp/rand"
"gonum.org/v1/plot"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
)
// An example of making a histogram.
func ExampleHistogram() {
rnd := rand.New(rand.NewSource(1))
// stdNorm returns the probability of drawing a
// value from a standard normal distribution.
stdNorm := func(x float64) float64 {
const sigma = 1.0
const mu = 0.0
const root2π = 2.50662827459517818309
return 1.0 / (sigma * root2π) * math.Exp(-((x-mu)*(x-mu))/(2*sigma*sigma))
}
n := 10000
vals := make(plotter.Values, n)
for i := 0; i < n; i++ {
vals[i] = rnd.NormFloat64()
}
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Histogram"
h, err := plotter.NewHist(vals, 16)
if err != nil {
log.Panic(err)
}
h.Normalize(1)
p.Add(h)
// The normal distribution function
norm := plotter.NewFunction(stdNorm)
norm.Color = color.RGBA{R: 255, A: 255}
norm.Width = vg.Points(2)
p.Add(norm)
err = p.Save(200, 200, "testdata/histogram.png")
if err != nil {
log.Panic(err)
}
}
func ExampleHistogram_logScaleY() {
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Histogram in log-y"
p.Y.Scale = plot.LogScale{}
p.Y.Tick.Marker = plot.LogTicks{}
p.Y.Label.Text = "Y"
p.X.Label.Text = "X"
h1, err := plotter.NewHist(plotter.Values{
-2, -2,
-1,
+3, +3, +3, +3,
+1, +1, +1, +1, +1, +1, +1, +1, +1, +1,
+1, +1, +1, +1, +1, +1, +1, +1, +1, +1,
}, 16)
if err != nil {
log.Fatal(err)
}
h1.LogY = true
h1.FillColor = color.RGBA{255, 0, 0, 255}
h2, err := plotter.NewHist(plotter.Values{
-3, -3, -3,
+2, +2, +2, +2, +2,
}, 16)
if err != nil {
log.Fatal(err)
}
h2.LogY = true
h2.FillColor = color.RGBA{0, 0, 255, 255}
p.Add(h1, h2, plotter.NewGrid())
err = p.Save(200, 200, "testdata/histogram_logy.png")
if err != nil {
log.Fatal(err)
}
}
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