94 lines
1.5 KiB
Go
94 lines
1.5 KiB
Go
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package main
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import (
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"fmt"
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"github.com/fogleman/gg"
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)
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func main() {
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// plot
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p := gg.NewPlotXY()
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p.LegNrow = 2
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p.LegAtBottom = false
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// x-values [-1, +1]
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npts := 21
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x := make([]float64, npts)
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for i := 0; i < npts; i++ {
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x[i] = -1 + 2*float64(i)/float64(npts-1)
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}
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// curve 1
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y1 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y1[i] = x[i]
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}
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c1 := p.AddCurve("y = x", x, y1)
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c1.M = "o"
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c1.C = "#000"
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c1.Mec = "#f00"
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// curve 2
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y2 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y2[i] = 2 * x[i]
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}
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c2 := p.AddCurve("y = 2x", x, y2)
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c2.M = "o"
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c2.Void = true
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// curve 3
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y3 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y3[i] = x[i] * x[i]
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}
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c3 := p.AddCurve("y = x²", x, y3)
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c3.M = "s"
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// curve 4
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y4 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y4[i] = 2 * x[i] * x[i]
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}
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c4 := p.AddCurve("y = 2x²", x, y4)
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c4.M = "s"
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c4.Void = true
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// curve 5
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y5 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y5[i] = -x[i]
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}
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c5 := p.AddCurve("y = -x", x, y5)
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c5.M = "+"
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// curve 6
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y6 := make([]float64, npts)
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for i := 0; i < npts; i++ {
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y6[i] = -2 * x[i]
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}
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c6 := p.AddCurve("y = -2x", x, y6)
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c6.M = "x"
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// curve 7
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y7 := make([]float64, npts)
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c7 := p.AddCurve("gopher", y7, x)
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c7.M = "img:examples/gopher30.png"
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c7.Me = 5
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c7.Ls = "none"
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// render graph
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height := 400
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if p.LegAtBottom {
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height = 500
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}
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dc := gg.NewContext(500, height)
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p.Render(dc)
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// save
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dc.SavePNG("/tmp/figure.png")
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fmt.Printf("file </tmp/figure.png> written\n")
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}
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