chart

README

chart -- chart package using the fync canvas library

The chart library works by reading data into a ChartBox structure, and then composing elements as needed. Elements (chart types: linechart, bar, column, scatter, attributes: axes, titles, and frames) are arranged within a scalable area defined by a top, bottom, left, right.

	// Open data files
	sr, err := os.Open("sin.d")
	if err != nil {
		return err
	}
	cr, err := os.Open("cos.d")
	if err != nil {
		return err
	}

	// Read in the data
	sine, err := chart.DataRead(sr)
	if err != nil {
		return err
	}
	cosine, err := chart.DataRead(cr)
	if err != nil {
		return err
	}
	sr.Close()
	cr.Close()


	// Compose elements
	sine.Zerobased, cosine.Zerobased = false, false

	// composite two charts
	cosine.Frame(canvas, 5)
	cosine.Label(canvas, 1.5, 10)
	cosine.YAxis(canvas, 1.2, -1.0, 1.0, 1.0, "%0.2f", true)
	cosine.Color = color.RGBA{0, 128, 0, 255}
	sine.Color = color.RGBA{128, 0, 0, 255}
	cosine.Scatter(canvas, 0.75)
	sine.Scatter(canvas, 0.75)

	// two charts side by side
	sine.Left = 10
	sine.Right = sine.Left + 40
	sine.Top, cosine.Top = 30, 30
	sine.Bottom, cosine.Bottom = 10, 10

	sine.CTitle(canvas, 2, 2)
	sine.Frame(canvas, 5)
	sine.Scatter(canvas, 0.5)

	offset := 45.0
	cosine.Left = sine.Left + offset
	cosine.Right = sine.Right + offset

	cosine.CTitle(canvas, 2, 2)
	cosine.Frame(canvas, 5)
	cosine.Scatter(canvas, 0.5)

Documentation

Overview

Package chart makes charts using the fync canvas package

Index

• func Grid(canvas fc.Canvas, left, bottom, width, height, size float64, color color.RGBA)
• type ChartBox
  • func DataRead(r io.Reader) (ChartBox, error)
  • func (c *ChartBox) Bar(canvas fc.Canvas, size float64)
  • func (c *ChartBox) CTitle(canvas fc.Canvas, size, offset float64)
  • func (c *ChartBox) Frame(canvas fc.Canvas, op float64)
  • func (c *ChartBox) HBar(canvas fc.Canvas, size, linespacing, textsize float64)
  • func (c *ChartBox) Label(canvas fc.Canvas, size float64, n int)
  • func (c *ChartBox) Lego(canvas fc.Canvas, step float64)
  • func (c *ChartBox) Line(canvas fc.Canvas, size float64)
  • func (c *ChartBox) Scatter(canvas fc.Canvas, size float64)
  • func (c *ChartBox) YAxis(canvas fc.Canvas, size, min, max, step float64, format string, gridlines bool)
• type NameValue

Functions

func Grid

func Grid(canvas fc.Canvas, left, bottom, width, height, size float64, color color.RGBA)

Grid makes a grid

Types

type ChartBox

type ChartBox struct {
	Title                    string
	Data                     []NameValue
	Color                    color.RGBA
	Top, Bottom, Left, Right float64
	Minvalue, Maxvalue       float64
	Zerobased                bool
}

ChartBox holds the essential data for making a chart

func DataRead

func DataRead(r io.Reader) (ChartBox, error)

DataRead reads tab separated values into a ChartBox default values for the top, bottom, left, right (90,50,10,90) are filled in as is the default color, black

func (*ChartBox) Bar

func (c *ChartBox) Bar(canvas fc.Canvas, size float64)

Bar makes a (column) bar chart

func (*ChartBox) CTitle

func (c *ChartBox) CTitle(canvas fc.Canvas, size, offset float64)

CTitle makes a centered title

func (*ChartBox) Frame

func (c *ChartBox) Frame(canvas fc.Canvas, op float64)

Frame makes a filled frame with the specified opacity (0-100)

func (*ChartBox) HBar

func (c *ChartBox) HBar(canvas fc.Canvas, size, linespacing, textsize float64)

HBar makes a horizontal bar chart

func (*ChartBox) Label

func (c *ChartBox) Label(canvas fc.Canvas, size float64, n int)

Label draws the x axis labels

func (*ChartBox) Lego

func (c *ChartBox) Lego(canvas fc.Canvas, step float64)

Lego makes a lego/waffle chart

func (*ChartBox) Line

func (c *ChartBox) Line(canvas fc.Canvas, size float64)

Line makes a line chart

func (*ChartBox) Scatter

func (c *ChartBox) Scatter(canvas fc.Canvas, size float64)

Scatter makes a scatter chart

func (*ChartBox) YAxis

func (c *ChartBox) YAxis(canvas fc.Canvas, size, min, max, step float64, format string, gridlines bool)

YAxis makes the Y axis with optional grid lines

type NameValue

type NameValue struct {
	Label string
	Note  string
	Value float64
}

NameValue is a name,value pair