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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
import (
"gonum.org/v1/plot"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
)
// Function implements the Plotter interface,
// drawing a line for the given function.
type Function struct {
F func(x float64) (y float64)
// XMin and XMax specify the range
// of x values to pass to F.
XMin, XMax float64
Samples int
draw.LineStyle
}
// NewFunction returns a Function that plots F using
// the default line style with 50 samples.
func NewFunction(f func(float64) float64) *Function {
return &Function{
F: f,
Samples: 50,
LineStyle: DefaultLineStyle,
}
}
// Plot implements the Plotter interface, drawing a line
// that connects each point in the Line.
func (f *Function) Plot(c draw.Canvas, p *plot.Plot) {
trX, trY := p.Transforms(&c)
min, max := f.XMin, f.XMax
if min == 0 && max == 0 {
min = p.X.Min
max = p.X.Max
}
d := (max - min) / float64(f.Samples-1)
line := make([]vg.Point, f.Samples)
for i := range line {
x := min + float64(i)*d
line[i].X = trX(x)
line[i].Y = trY(f.F(x))
}
c.StrokeLines(f.LineStyle, c.ClipLinesXY(line)...)
}
// Thumbnail draws a line in the given style down the
// center of a DrawArea as a thumbnail representation
// of the LineStyle of the function.
func (f Function) Thumbnail(c *draw.Canvas) {
y := c.Center().Y
c.StrokeLine2(f.LineStyle, c.Min.X, y, c.Max.X, y)
}
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