bubbles_example_test.go

Documentation: gonum.org/v1/plot/plotter

     1  // Copyright ©2015 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package plotter_test
     6  
     7  import (
     8  	"image/color"
     9  	"log"
    10  	"math"
    11  
    12  	"golang.org/x/exp/rand"
    13  
    14  	"gonum.org/v1/plot"
    15  	"gonum.org/v1/plot/plotter"
    16  	"gonum.org/v1/plot/vg"
    17  	"gonum.org/v1/plot/vg/draw"
    18  )
    19  
    20  // ExampleScatter_bubbles draws some scatter points.
    21  // Each point is plotted with a different radius size depending on
    22  // external criteria.
    23  func ExampleScatter_bubbles() {
    24  	rnd := rand.New(rand.NewSource(1))
    25  
    26  	// randomTriples returns some random but correlated x, y, z triples
    27  	randomTriples := func(n int) plotter.XYZs {
    28  		data := make(plotter.XYZs, n)
    29  		for i := range data {
    30  			if i == 0 {
    31  				data[i].X = rnd.Float64()
    32  			} else {
    33  				data[i].X = data[i-1].X + 2*rnd.Float64()
    34  			}
    35  			data[i].Y = data[i].X + 10*rnd.Float64()
    36  			data[i].Z = data[i].X
    37  		}
    38  		return data
    39  	}
    40  
    41  	n := 10
    42  	scatterData := randomTriples(n)
    43  
    44  	// Calculate the range of Z values.
    45  	minZ, maxZ := math.Inf(1), math.Inf(-1)
    46  	for _, xyz := range scatterData {
    47  		if xyz.Z > maxZ {
    48  			maxZ = xyz.Z
    49  		}
    50  		if xyz.Z < minZ {
    51  			minZ = xyz.Z
    52  		}
    53  	}
    54  
    55  	p := plot.New()
    56  	p.Title.Text = "Bubbles"
    57  	p.X.Label.Text = "X"
    58  	p.Y.Label.Text = "Y"
    59  
    60  	sc, err := plotter.NewScatter(scatterData)
    61  	if err != nil {
    62  		log.Panic(err)
    63  	}
    64  
    65  	// Specify style for individual points.
    66  	sc.GlyphStyleFunc = func(i int) draw.GlyphStyle {
    67  		c := color.RGBA{R: 196, B: 128, A: 255}
    68  		var minRadius, maxRadius = vg.Points(1), vg.Points(20)
    69  		rng := maxRadius - minRadius
    70  		_, _, z := scatterData.XYZ(i)
    71  		d := (z - minZ) / (maxZ - minZ)
    72  		r := vg.Length(d)*rng + minRadius
    73  		return draw.GlyphStyle{Color: c, Radius: r, Shape: draw.CircleGlyph{}}
    74  	}
    75  	p.Add(sc)
    76  
    77  	err = p.Save(200, 200, "testdata/bubbles.png")
    78  	if err != nil {
    79  		log.Panic(err)
    80  	}
    81  }
    82
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