plot/plot.go at master · ffhelicopter/plot · GitHub

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// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package plot

import (

"image/color"

"io"

"math"

"os"

"path/filepath"

"strings"

"gonum.org/v1/plot/vg"

"gonum.org/v1/plot/vg/draw"

)

var (

// DefaultFont is the name of the default font for plot text.

DefaultFont = "Times-Roman"

)

// Plot is the basic type representing a plot.

type Plot struct {

Title struct {

// Text is the text of the plot title. If

// Text is the empty string then the plot

// will not have a title.

Text string

// Padding is the amount of padding

// between the bottom of the title and

// the top of the plot.

Padding vg.Length

draw.TextStyle

}

// BackgroundColor is the background color of the plot.

// The default is White.

BackgroundColor color.Color

// X and Y are the horizontal and vertical axes

// of the plot respectively.

X, Y Axis

// Legend is the plot's legend.

Legend Legend

// plotters are drawn by calling their Plot method

// after the axes are drawn.

plotters []Plotter

}

// Plotter is an interface that wraps the Plot method.

// Some standard implementations of Plotter can be

// found in the gonum.org/v1/plot/plotter

// package, documented here:

// https://godoc.org/gonum.org/v1/plot/plotter

type Plotter interface {

// Plot draws the data to a draw.Canvas.

Plot(draw.Canvas, *Plot)

}

// DataRanger wraps the DataRange method.

type DataRanger interface {

// DataRange returns the range of X and Y values.

DataRange() (xmin, xmax, ymin, ymax float64)

}

const (

vertical = true

horizontal = false

)

// New returns a new plot with some reasonable

// default settings.

func New() (*Plot, error) {

titleFont, err := vg.MakeFont(DefaultFont, 12)

if err != nil {

return nil, err

}

x, err := makeAxis(horizontal)

if err != nil {

return nil, err

}

y, err := makeAxis(vertical)

if err != nil {

return nil, err

}

legend, err := NewLegend()

if err != nil {

return nil, err

}

p := &Plot{

BackgroundColor: color.White,

X: x,

Y: y,

Legend: legend,

}

p.Title.TextStyle = draw.TextStyle{

Color: color.Black,

Font: titleFont,

XAlign: draw.XCenter,

YAlign: draw.YTop,

}

return p, nil

}

// Add adds a Plotters to the plot.

// If the plotters implements DataRanger then the

// minimum and maximum values of the X and Y

// axes are changed if necessary to fit the range of

// the data.

// When drawing the plot, Plotters are drawn in the

// order in which they were added to the plot.

func (p *Plot) Add(ps ...Plotter) {

for _, d := range ps {

if x, ok := d.(DataRanger); ok {

xmin, xmax, ymin, ymax := x.DataRange()

p.X.Min = math.Min(p.X.Min, xmin)

p.X.Max = math.Max(p.X.Max, xmax)

p.Y.Min = math.Min(p.Y.Min, ymin)

p.Y.Max = math.Max(p.Y.Max, ymax)

}

p.plotters = append(p.plotters, ps...)

}

// Draw draws a plot to a draw.Canvas.

// Plotters are drawn in the order in which they were

// added to the plot. Plotters that implement the

// GlyphBoxer interface will have their GlyphBoxes

// taken into account when padding the plot so that

// none of their glyphs are clipped.

func (p *Plot) Draw(c draw.Canvas) {

if p.BackgroundColor != nil {

c.SetColor(p.BackgroundColor)

c.Fill(c.Rectangle.Path())

}

if p.Title.Text != "" {

c.FillText(p.Title.TextStyle, vg.Point{X: c.Center().X, Y: c.Max.Y}, p.Title.Text)

c.Max.Y -= p.Title.Height(p.Title.Text) - p.Title.Font.Extents().Descent

c.Max.Y -= p.Title.Padding

}

p.X.sanitizeRange()

x := horizontalAxis{p.X}

p.Y.sanitizeRange()

y := verticalAxis{p.Y}

ywidth := y.size()

xheight := x.size()

x.draw(padX(p, draw.Crop(c, ywidth, 0, 0, 0)))

y.draw(padY(p, draw.Crop(c, 0, 0, xheight, 0)))

dataC := padY(p, padX(p, draw.Crop(c, ywidth, 0, xheight, 0)))

for _, data := range p.plotters {

data.Plot(dataC, p)

}

p.Legend.Draw(draw.Crop(c, ywidth, 0, xheight, 0))

}

// DataCanvas returns a new draw.Canvas that

// is the subset of the given draw area into which

// the plot data will be drawn.

func (p *Plot) DataCanvas(da draw.Canvas) draw.Canvas {

if p.Title.Text != "" {

da.Max.Y -= p.Title.Height(p.Title.Text) - p.Title.Font.Extents().Descent

da.Max.Y -= p.Title.Padding

}

p.X.sanitizeRange()

x := horizontalAxis{p.X}

p.Y.sanitizeRange()

y := verticalAxis{p.Y}

return padY(p, padX(p, draw.Crop(da, y.size(), 0, x.size(), 0)))

}

// DrawGlyphBoxes draws red outlines around the plot's

// GlyphBoxes. This is intended for debugging.

func (p *Plot) DrawGlyphBoxes(c *draw.Canvas) {

c.SetColor(color.RGBA{R: 255, A: 255})

for _, b := range p.GlyphBoxes(p) {

b.Rectangle.Min.X += c.X(b.X)

b.Rectangle.Min.Y += c.Y(b.Y)

c.Stroke(b.Rectangle.Path())

}

// padX returns a draw.Canvas that is padded horizontally

// so that glyphs will no be clipped.

func padX(p *Plot, c draw.Canvas) draw.Canvas {

glyphs := p.GlyphBoxes(p)

l := leftMost(&c, glyphs)

xAxis := horizontalAxis{p.X}

glyphs = append(glyphs, xAxis.GlyphBoxes(p)...)

r := rightMost(&c, glyphs)

minx := c.Min.X - l.Min.X

maxx := c.Max.X - (r.Min.X + r.Size().X)

lx := vg.Length(l.X)

rx := vg.Length(r.X)

n := (lx*maxx - rx*minx) / (lx - rx)

m := ((lx-1)*maxx - rx*minx + minx) / (lx - rx)

return draw.Canvas{

Canvas: vg.Canvas(c),

Rectangle: vg.Rectangle{

Min: vg.Point{X: n, Y: c.Min.Y},

Max: vg.Point{X: m, Y: c.Max.Y},

}

// rightMost returns the right-most GlyphBox.

func rightMost(c *draw.Canvas, boxes []GlyphBox) GlyphBox {

maxx := c.Max.X

r := GlyphBox{X: 1}

for _, b := range boxes {

if b.Size().X <= 0 {

continue

}

if x := c.X(b.X) + b.Min.X + b.Size().X; x > maxx && b.X <= 1 {

maxx = x

r = b

}

return r

}

// leftMost returns the left-most GlyphBox.

func leftMost(c *draw.Canvas, boxes []GlyphBox) GlyphBox {

minx := c.Min.X

l := GlyphBox{}

for _, b := range boxes {

if b.Size().X <= 0 {

continue

}

if x := c.X(b.X) + b.Min.X; x < minx && b.X >= 0 {

minx = x

l = b

}

return l

}

// padY returns a draw.Canvas that is padded vertically

// so that glyphs will no be clipped.

func padY(p *Plot, c draw.Canvas) draw.Canvas {

glyphs := p.GlyphBoxes(p)

b := bottomMost(&c, glyphs)

yAxis := verticalAxis{p.Y}

glyphs = append(glyphs, yAxis.GlyphBoxes(p)...)

t := topMost(&c, glyphs)

miny := c.Min.Y - b.Min.Y

maxy := c.Max.Y - (t.Min.Y + t.Size().Y)

by := vg.Length(b.Y)

ty := vg.Length(t.Y)

n := (by*maxy - ty*miny) / (by - ty)

m := ((by-1)*maxy - ty*miny + miny) / (by - ty)

return draw.Canvas{

Canvas: vg.Canvas(c),

Rectangle: vg.Rectangle{

Min: vg.Point{Y: n, X: c.Min.X},

Max: vg.Point{Y: m, X: c.Max.X},

}

// topMost returns the top-most GlyphBox.

func topMost(c *draw.Canvas, boxes []GlyphBox) GlyphBox {

maxy := c.Max.Y

t := GlyphBox{Y: 1}

for _, b := range boxes {

if b.Size().Y <= 0 {

continue

}

if y := c.Y(b.Y) + b.Min.Y + b.Size().Y; y > maxy && b.Y <= 1 {

maxy = y

t = b

}

return t

}

// bottomMost returns the bottom-most GlyphBox.

func bottomMost(c *draw.Canvas, boxes []GlyphBox) GlyphBox {

miny := c.Min.Y

l := GlyphBox{}

for _, b := range boxes {

if b.Size().Y <= 0 {

continue

}

if y := c.Y(b.Y) + b.Min.Y; y < miny && b.Y >= 0 {

miny = y

l = b

}

return l

}

// Transforms returns functions to transfrom

// from the x and y data coordinate system to

// the draw coordinate system of the given

// draw area.

func (p *Plot) Transforms(c *draw.Canvas) (x, y func(float64) vg.Length) {

x = func(x float64) vg.Length { return c.X(p.X.Norm(x)) }

y = func(y float64) vg.Length { return c.Y(p.Y.Norm(y)) }

return

}

// GlyphBoxer wraps the GlyphBoxes method.

// It should be implemented by things that meet

// the Plotter interface that draw glyphs so that

// their glyphs are not clipped if drawn near the

// edge of the draw.Canvas.

// When computing padding, the plot ignores

// GlyphBoxes as follows:

// If the Size.X > 0 and the X value is not in range

// of the X axis then the box is ignored.

// If Size.Y > 0 and the Y value is not in range of

// the Y axis then the box is ignored.

// Also, GlyphBoxes with Size.X <= 0 are ignored

// when computing horizontal padding and

// GlyphBoxes with Size.Y <= 0 are ignored when

// computing vertical padding. This is useful

// for things like box plots and bar charts where

// the boxes and bars are considered to be glyphs

// in the X direction (and thus need padding), but

// may be clipped in the Y direction (and do not

// need padding).

type GlyphBoxer interface {

GlyphBoxes(*Plot) []GlyphBox

}

// A GlyphBox describes the location of a glyph

// and the offset/size of its bounding box.

// If the Rectangle.Size().X is non-positive (<= 0) then

// the GlyphBox is ignored when computing the

// horizontal padding, and likewise with

// Rectangle.Size().Y and the vertical padding.

type GlyphBox struct {

// The glyph location in normalized coordinates.

X, Y float64

// Rectangle is the offset of the glyph's minimum drawing

// point relative to the glyph location and its size.

vg.Rectangle

}

// GlyphBoxes returns the GlyphBoxes for all plot

// data that meet the GlyphBoxer interface.

func (p *Plot) GlyphBoxes(*Plot) (boxes []GlyphBox) {

for _, d := range p.plotters {

gb, ok := d.(GlyphBoxer)

if !ok {

continue

}

for _, b := range gb.GlyphBoxes(p) {

if b.Size().X > 0 && (b.X < 0 || b.X > 1) {

continue

}

if b.Size().Y > 0 && (b.Y < 0 || b.Y > 1) {

continue

}

boxes = append(boxes, b)

}

return

}

// NominalX configures the plot to have a nominal X

// axis—an X axis with names instead of numbers. The

// X location corresponding to each name are the integers,

// e.g., the x value 0 is centered above the first name and

// 1 is above the second name, etc. Labels for x values

// that do not end up in range of the X axis will not have

// tick marks.

func (p *Plot) NominalX(names ...string) {

p.X.Tick.Width = 0

p.X.Tick.Length = 0

p.X.Width = 0

p.Y.Padding = p.X.Tick.Label.Width(names[0]) / 2

ticks := make([]Tick, len(names))

for i, name := range names {

ticks[i] = Tick{float64(i), name}

}

p.X.Tick.Marker = ConstantTicks(ticks)

}

// HideX configures the X axis so that it will not be drawn.

func (p *Plot) HideX() {

p.X.Tick.Length = 0

p.X.Width = 0

p.X.Tick.Marker = ConstantTicks([]Tick{})

}

// HideY configures the Y axis so that it will not be drawn.

func (p *Plot) HideY() {

p.Y.Tick.Length = 0

p.Y.Width = 0

p.Y.Tick.Marker = ConstantTicks([]Tick{})

}

// HideAxes hides the X and Y axes.

func (p *Plot) HideAxes() {

p.HideX()

p.HideY()

}

// NominalY is like NominalX, but for the Y axis.

func (p *Plot) NominalY(names ...string) {

p.Y.Tick.Width = 0

p.Y.Tick.Length = 0

p.Y.Width = 0

p.X.Padding = p.Y.Tick.Label.Height(names[0]) / 2

ticks := make([]Tick, len(names))

for i, name := range names {

ticks[i] = Tick{float64(i), name}

}

p.Y.Tick.Marker = ConstantTicks(ticks)

}

// WriterTo returns an io.WriterTo that will write the plot as

// the specified image format.

// Supported formats are:

// eps, jpg|jpeg, pdf, png, svg, and tif|tiff.

func (p *Plot) WriterTo(w, h vg.Length, format string) (io.WriterTo, error) {

c, err := draw.NewFormattedCanvas(w, h, format)

if err != nil {

return nil, err

}

p.Draw(draw.New(c))

return c, nil

}

// Save saves the plot to an image file. The file format is determined

// by the extension.

// Supported extensions are:

// .eps, .jpg, .jpeg, .pdf, .png, .svg, .tif and .tiff.

func (p *Plot) Save(w, h vg.Length, file string) (err error) {

f, err := os.Create(file)

if err != nil {

return err

}

defer func() {

e := f.Close()

if err == nil {

err = e

}

}()

format := strings.ToLower(filepath.Ext(file))

if len(format) != 0 {

format = format[1:]

}

c, err := p.WriterTo(w, h, format)

if err != nil {

return err

}

_, err = c.WriteTo(f)

return err

}

plot/plot.go at master · ffhelicopter/plot · GitHub

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