chart

package module
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 Go to latest Published: Jul 19, 2016 License: MIT Imports: 15 Imported by: 0

README

go-chart

Build Status

Package chart is a very simple golang native charting library that supports timeseries and continuous line charts.

The v1.0 release has been tagged so things should be more or less stable, if something changes please log an issue.

Installation

To install chart run the following:

> go get -u github.com/wcharczuk/go-chart

Most of the components are interchangeable so feel free to crib whatever you want.

Output Examples

Spark Lines:

Single axis:

Two axis:

Simple Moving Average:

Bollinger Bounds:

Code Examples

Actual chart configurations and examples can be found in the ./examples/ directory. They are web servers, so start them with go run main.go then access http://localhost:8080 to see the output.

Usage

Everything starts with the chart.Chart object. The bare minimum to draw a chart would be the following:


import (
    ...
    "bytes"
    ...
    "github.com/wcharczuk/go-chart" //exposes "chart"
)

graph := chart.Chart{
    Series: []chart.Series{
        chart.ContinuousSeries{
            XValues: []float64{1.0, 2.0, 3.0, 4.0},
            YValues: []float64{1.0, 2.0, 3.0, 4.0},
        },
    },
}

buffer := bytes.NewBuffer([]byte{})
err := graph.Render(chart.PNG, buffer)

Explanation of the above: A chart can have many Series, a Series is a collection of things that need to be drawn according to the X range and the Y range(s).

Here, we have a single series with x range values as float64s, rendered to a PNG. Note; we can pass any type of io.Writer into Render(...), meaning that we can render the chart to a file or a resonse or anything else that implements io.Writer.

API Overview

Everything on the chart.Chart object has defaults that can be overriden. Whenever a developer sets a property on the chart object, it is to be assumed that value will be used instead of the default. One complication here is any object's root chart.Style object (i.e named Style) and the Show property specifically, if any other property is set and the Show property is unset, it is assumed to be it's default value of False.

The best way to see the api in action is to look at the examples in the ./examples/ directory.

Design Philosophy

I wanted to make a charting library that used only native golang, that could be stood up on a server (i.e. it had built in fonts).

The goal with the API itself is to have the "zero value be useful", and to require the user to not code more than they absolutely needed.

Contributions

This library is super early but contributions are welcome.

Documentation

Index

Constants

View Source 
const (
	// DefaultChartHeight is the default chart height.
	DefaultChartHeight = 400
	// DefaultChartWidth is the default chart width.
	DefaultChartWidth = 1024
	// DefaultStrokeWidth is the default chart line/stroke width.
	DefaultStrokeWidth = 1.0
	// DefaultAxisLineWidth is the line width of the axis lines.
	DefaultAxisLineWidth = 1.0
	//DefaultDPI is the default dots per inch for the chart.
	DefaultDPI = 92.0
	// DefaultMinimumFontSize is the default minimum font size.
	DefaultMinimumFontSize = 8.0
	// DefaultFontSize is the default font size.
	DefaultFontSize = 10.0
	// DefaultTitleFontSize is the default title font size.
	DefaultTitleFontSize = 18.0
	// DefaultAnnotationDeltaWidth is the width of the left triangle out of annotations.
	DefaultAnnotationDeltaWidth = 10
	// DefaultAnnotationFontSize is the font size of annotations.
	DefaultAnnotationFontSize = 10.0
	// DefaultAxisFontSize is the font size of the axis labels.
	DefaultAxisFontSize = 10.0
	// DefaultTitleTop is the default distance from the top of the chart to put the title.
	DefaultTitleTop = 10

	// DefaultYAxisMargin is the default distance from the right of the canvas to the y axis labels.
	DefaultYAxisMargin = 10
	// DefaultXAxisMargin is the default distance from bottom of the canvas to the x axis labels.
	DefaultXAxisMargin = 10

	//DefaultVerticalTickHeight is half the margin.
	DefaultVerticalTickHeight = DefaultXAxisMargin >> 1
	//DefaultHorizontalTickWidth is half the margin.
	DefaultHorizontalTickWidth = DefaultYAxisMargin >> 1

	// DefaultTickCount is the default number of ticks to show
	DefaultTickCount = 10
	// DefaultTickCountSanityCheck is a hard limit on number of ticks to prevent infinite loops.
	DefaultTickCountSanityCheck = 1 << 10 //1024

	// DefaultMinimumTickHorizontalSpacing is the minimum distance between horizontal ticks.
	DefaultMinimumTickHorizontalSpacing = 20
	// DefaultMinimumTickVerticalSpacing is the minimum distance between vertical ticks.
	DefaultMinimumTickVerticalSpacing = 20

	// DefaultDateFormat is the default date format.
	DefaultDateFormat = "2006-01-02"
	// DefaultDateHourFormat is the date format for hour timestamp formats.
	DefaultDateHourFormat = "01-02 3PM"
	// DefaultDateMinuteFormat is the date format for minute range timestamp formats.
	DefaultDateMinuteFormat = time.Kitchen
	// DefaultFloatFormat is the default float format.
	DefaultFloatFormat = "%.2f"
	// DefaultPercentValueFormat is the default percent format.
	DefaultPercentValueFormat = "%0.2f%%"
)
View Source 
const (
	// DefaultMACDPeriodPrimary is the long window.
	DefaultMACDPeriodPrimary = 26
	// DefaultMACDPeriodSecondary is the short window.
	DefaultMACDPeriodSecondary = 12
	// DefaultMACDSignalPeriod is the signal period to compute for the MACD.
	DefaultMACDSignalPeriod = 9
)
View Source 
const (
	// DefaultEMAPeriod is the default EMA period used in the sigma calculation.
	DefaultEMAPeriod = 12
)
View Source 
const (
	// DefaultSimpleMovingAveragePeriod is the default number of values to average.
	DefaultSimpleMovingAveragePeriod = 16
)

Variables

View Source 
var (
	// DefaultBackgroundColor is the default chart background color.
	// It is equivalent to css color:white.
	DefaultBackgroundColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
	// DefaultBackgroundStrokeColor is the default chart border color.
	// It is equivalent to color:white.
	DefaultBackgroundStrokeColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
	// DefaultCanvasColor is the default chart canvas color.
	// It is equivalent to css color:white.
	DefaultCanvasColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
	// DefaultCanvasStrokeColor is the default chart canvas stroke color.
	// It is equivalent to css color:white.
	DefaultCanvasStrokeColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
	// DefaultTextColor is the default chart text color.
	// It is equivalent to #333333.
	DefaultTextColor = drawing.Color{R: 51, G: 51, B: 51, A: 255}
	// DefaultAxisColor is the default chart axis line color.
	// It is equivalent to #333333.
	DefaultAxisColor = drawing.Color{R: 51, G: 51, B: 51, A: 255}
	// DefaultStrokeColor is the default chart border color.
	// It is equivalent to #efefef.
	DefaultStrokeColor = drawing.Color{R: 239, G: 239, B: 239, A: 255}
	// DefaultFillColor is the default fill color.
	// It is equivalent to #0074d9.
	DefaultFillColor = drawing.Color{R: 0, G: 217, B: 116, A: 255}
	// DefaultAnnotationFillColor is the default annotation background color.
	DefaultAnnotationFillColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
	// DefaultGridLineColor is the default grid line color.
	DefaultGridLineColor = drawing.Color{R: 239, G: 239, B: 239, A: 255}
)
View Source 
var (
	// DashArrayDots is a dash array that represents '....' style stroke dashes.
	DashArrayDots = []int{1, 1}
	// DashArrayDashesSmall is a dash array that represents '- - -' style stroke dashes.
	DashArrayDashesSmall = []int{3, 3}
	// DashArrayDashesMedium is a dash array that represents '-- -- --' style stroke dashes.
	DashArrayDashesMedium = []int{5, 5}
	// DashArrayDashesLarge is a dash array that represents '----- ----- -----' style stroke dashes.
	DashArrayDashesLarge = []int{10, 10}
)
View Source 
var (
	// DefaultAnnotationPadding is the padding around an annotation.
	DefaultAnnotationPadding = Box{Top: 5, Left: 5, Right: 5, Bottom: 5}
	// DefaultBackgroundPadding is the default canvas padding config.
	DefaultBackgroundPadding = Box{Top: 5, Left: 5, Right: 5, Bottom: 5}
)
View Source 
var (
	// DefaultSeriesStrokeColors are a couple default series colors.
	DefaultSeriesStrokeColors = []drawing.Color{
		{R: 0, G: 116, B: 217, A: 255},
		{R: 0, G: 217, B: 116, A: 255},
		{R: 217, G: 0, B: 116, A: 255},
	}
)

Functions

func AbsInt 

func AbsInt(value int) int

AbsInt returns the absolute value of an integer.

func DrawAnnotation 

func DrawAnnotation(r Renderer, canvasBox Box, style Style, lx, ly int, label string)

DrawAnnotation draws an anotation with a renderer.

func DrawBoundedSeries 

func DrawBoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, s Style, bbs BoundedValueProvider, drawOffsetIndexes ...int)

DrawBoundedSeries draws a series that implements BoundedValueProvider.

func DrawBox 

func DrawBox(r Renderer, b Box, s Style)

DrawBox draws a box with a given style.

func DrawHistogramSeries 

func DrawHistogramSeries(r Renderer, canvasBox Box, xrange, yrange Range, s Style, vs ValueProvider, barWidths ...int)

DrawHistogramSeries draws a value provider as boxes from 0.

func DrawLineSeries 

func DrawLineSeries(r Renderer, canvasBox Box, xrange, yrange Range, s Style, vs ValueProvider)

DrawLineSeries draws a line series with a renderer.

func DrawText 

func DrawText(r Renderer, text string, x, y int, s Style)

DrawText draws text with a given style.

func DrawTextCentered 

func DrawTextCentered(r Renderer, text string, x, y int, s Style)

DrawTextCentered draws text with a given style centered.

func FloatValueFormatter 

func FloatValueFormatter(v interface{}) string

FloatValueFormatter is a ValueFormatter for float64.

func FloatValueFormatterWithFormat 

func FloatValueFormatterWithFormat(v interface{}, floatFormat string) string

FloatValueFormatterWithFormat is a ValueFormatter for float64 with a given format.

func GetDefaultFont 

func GetDefaultFont() (*truetype.Font, error)

GetDefaultFont returns the default font (Roboto-Medium).

func GetDefaultSeriesStrokeColor 

func GetDefaultSeriesStrokeColor(index int) drawing.Color

GetDefaultSeriesStrokeColor returns a color from the default list by index. NOTE: the index will wrap around (using a modulo).g

func GetRoundToForDelta 

func GetRoundToForDelta(delta float64) float64

GetRoundToForDelta returns a `roundTo` value for a given delta.

func MaxInt 

func MaxInt(values ...int) int

MaxInt returns the maximum of a set of integers.

func MinAndMax 

func MinAndMax(values ...float64) (min float64, max float64)

MinAndMax returns both the min and max in one pass.

func MinAndMaxOfTime 

func MinAndMaxOfTime(values ...time.Time) (min time.Time, max time.Time)

MinAndMaxOfTime returns the min and max of a given set of times in one pass.

func MinInt 

func MinInt(values ...int) int

MinInt returns the minimum of a set of integers.

func PercentDifference 

func PercentDifference(v1, v2 float64) float64

PercentDifference computes the percentage difference between two values. The formula is (v2-v1)/v1.

func PercentValueFormatter 

func PercentValueFormatter(v interface{}) string

PercentValueFormatter is a formatter for percent values. NOTE: it normalizes the values, i.e. multiplies by 100.0.

func RoundDown 

func RoundDown(value, roundTo float64) float64

RoundDown rounds down to a given roundTo value.

func RoundUp 

func RoundUp(value, roundTo float64) float64

RoundUp rounds up to a given roundTo value.

func Seq 

func Seq(start, end float64, steps ...float64) []float64

Seq produces an array of floats from [start,end] by optional steps.

func SeqDays 

func SeqDays(days int) []time.Time

SeqDays generates a sequence of timestamps by day, from -days to today.

func SeqRand 

func SeqRand(samples int, scale float64) []float64

SeqRand generates a random sequence.

func Slices 

func Slices(count int, total float64) []float64

Slices generates N slices that span the total. The resulting array will be intermediate indexes until total.

func TimeHourValueFormatter 

func TimeHourValueFormatter(v interface{}) string

TimeHourValueFormatter is a ValueFormatter for timestamps.

func TimeMinuteValueFormatter 

func TimeMinuteValueFormatter(v interface{}) string

TimeMinuteValueFormatter is a ValueFormatter for timestamps.

func TimeToFloat64 

func TimeToFloat64(t time.Time) float64

TimeToFloat64 returns a float64 representation of a time.

func TimeValueFormatter 

func TimeValueFormatter(v interface{}) string

TimeValueFormatter is a ValueFormatter for timestamps.

func TimeValueFormatterWithFormat 

func TimeValueFormatterWithFormat(v interface{}, dateFormat string) string

TimeValueFormatterWithFormat is a ValueFormatter for timestamps with a given format.

Types

type Annotation 

type Annotation struct {
	X, Y  float64
	Label string
}

Annotation is a label on the chart.

type AnnotationSeries 

type AnnotationSeries struct {
	Name        string
	Style       Style
	YAxis       YAxisType
	Annotations []Annotation
}

AnnotationSeries is a series of labels on the chart.

func (AnnotationSeries) GetName 

func (as AnnotationSeries) GetName() string

GetName returns the name of the time series.

func (AnnotationSeries) GetStyle 

func (as AnnotationSeries) GetStyle() Style

GetStyle returns the line style.

func (AnnotationSeries) GetYAxis 

func (as AnnotationSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (AnnotationSeries) Measure 

func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) Box

Measure returns a bounds box of the series.

func (AnnotationSeries) Render 

func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render draws the series.

type Axis 

type Axis interface {
	GetName() string
	GetStyle() Style
	GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick
	GetGridLines(ticks []Tick) []GridLine
	Render(c *Chart, r Renderer, canvasBox Box, ra Range, ticks []Tick)
}

Axis is a chart feature detailing what values happen where.

type BollingerBandsSeries 

type BollingerBandsSeries struct {
	Name  string
	Style Style
	YAxis YAxisType

	Period      int
	K           float64
	InnerSeries ValueProvider
	// contains filtered or unexported fields
}

BollingerBandsSeries draws bollinger bands for an inner series. Bollinger bands are defined by two lines, one at SMA+k*stddev, one at SMA-k*stdev.

func (*BollingerBandsSeries) GetBoundedLastValue 

func (bbs *BollingerBandsSeries) GetBoundedLastValue() (x, y1, y2 float64)

GetBoundedLastValue returns the last bounded value for the series.

func (*BollingerBandsSeries) GetBoundedValue 

func (bbs *BollingerBandsSeries) GetBoundedValue(index int) (x, y1, y2 float64)

GetBoundedValue gets the bounded value for the series.

func (BollingerBandsSeries) GetK 

func (bbs BollingerBandsSeries) GetK(defaults ...float64) float64

GetK returns the K value.

func (BollingerBandsSeries) GetName 

func (bbs BollingerBandsSeries) GetName() string

GetName returns the name of the time series.

func (BollingerBandsSeries) GetPeriod 

func (bbs BollingerBandsSeries) GetPeriod() int

GetPeriod returns the window size.

func (BollingerBandsSeries) GetStyle 

func (bbs BollingerBandsSeries) GetStyle() Style

GetStyle returns the line style.

func (BollingerBandsSeries) GetYAxis 

func (bbs BollingerBandsSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (*BollingerBandsSeries) Len 

func (bbs *BollingerBandsSeries) Len() int

Len returns the number of elements in the series.

func (*BollingerBandsSeries) Render 

func (bbs *BollingerBandsSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type BoundedLastValueProvider 

type BoundedLastValueProvider interface {
	GetBoundedLastValue() (x, y1, y2 float64)
}

BoundedLastValueProvider is a special type of value provider that can return it's (potentially computed) bounded last value.

type BoundedValueProvider 

type BoundedValueProvider interface {
	Len() int
	GetBoundedValue(index int) (x, y1, y2 float64)
}

BoundedValueProvider allows series to return a range.

type Box 

type Box struct {
	Top    int
	Left   int
	Right  int
	Bottom int
}

Box represents the main 4 dimensions of a box.

func MeasureAnnotation 

func MeasureAnnotation(r Renderer, canvasBox Box, s Style, lx, ly int, label string) Box

MeasureAnnotation measures how big an annotation would be.

func (Box) Aspect 

func (b Box) Aspect() float64

Aspect returns the aspect ratio of the box.

func (Box) Center 

func (b Box) Center() (x, y int)

Center returns the center of the box

func (Box) Clone 

func (b Box) Clone() Box

Clone returns a new copy of the box.

func (Box) Constrain 

func (b Box) Constrain(other Box) Box

Constrain is similar to `Fit` except that it will work more literally like the opposite of grow.

func (Box) Equals 

func (b Box) Equals(other Box) bool

Equals returns if the box equals another box.

func (Box) Fit 

func (b Box) Fit(other Box) Box

Fit is functionally the inverse of grow. Fit maintains the original aspect ratio of the `other` box, but constrains it to the bounds of the target box.

func (Box) GetBottom 

func (b Box) GetBottom(defaults ...int) int

GetBottom returns a coalesced value with a default.

func (Box) GetLeft 

func (b Box) GetLeft(defaults ...int) int

GetLeft returns a coalesced value with a default.

func (Box) GetRight 

func (b Box) GetRight(defaults ...int) int

GetRight returns a coalesced value with a default.

func (Box) GetTop 

func (b Box) GetTop(defaults ...int) int

GetTop returns a coalesced value with a default.

func (Box) Grow 

func (b Box) Grow(other Box) Box

Grow grows a box based on another box.

func (Box) Height 

func (b Box) Height() int

Height returns the height

func (Box) IsBiggerThan 

func (b Box) IsBiggerThan(other Box) bool

IsBiggerThan returns if a box is bigger than another box.

func (Box) IsSmallerThan 

func (b Box) IsSmallerThan(other Box) bool

IsSmallerThan returns if a box is smaller than another box.

func (Box) IsZero 

func (b Box) IsZero() bool

IsZero returns if the box is set or not.

func (Box) OuterConstrain 

func (b Box) OuterConstrain(bounds, other Box) Box

OuterConstrain is similar to `Constraint` with the difference that it applies corrections

func (Box) Shift 

func (b Box) Shift(x, y int) Box

Shift pushes a box by x,y.

func (Box) String 

func (b Box) String() string

String returns a string representation of the box.

func (Box) Width 

func (b Box) Width() int

Width returns the width

type Chart 

type Chart struct {
	Title      string
	TitleStyle Style

	Width  int
	Height int
	DPI    float64

	Background Style
	Canvas     Style

	XAxis          XAxis
	YAxis          YAxis
	YAxisSecondary YAxis

	Font *truetype.Font

	Series   []Series
	Elements []Renderable
	// contains filtered or unexported fields
}

Chart is what we're drawing.

func (Chart) Box 

func (c Chart) Box() Box

Box returns the chart bounds as a box.

func (Chart) GetDPI 

func (c Chart) GetDPI(defaults ...float64) float64

GetDPI returns the dpi for the chart.

func (Chart) GetFont 

func (c Chart) GetFont() *truetype.Font

GetFont returns the text font.

func (Chart) GetHeight 

func (c Chart) GetHeight() int

GetHeight returns the chart height or the default value.

func (Chart) GetWidth 

func (c Chart) GetWidth() int

GetWidth returns the chart width or the default value.

func (Chart) Render 

func (c Chart) Render(rp RendererProvider, w io.Writer) error

Render renders the chart with the given renderer to the given io.Writer.

type ContinuousSeries 

type ContinuousSeries struct {
	Name  string
	Style Style

	YAxis YAxisType

	XValues []float64
	YValues []float64
}

ContinuousSeries represents a line on a chart.

func (ContinuousSeries) GetLastValue 

func (cs ContinuousSeries) GetLastValue() (float64, float64)

GetLastValue gets the last value.

func (ContinuousSeries) GetName 

func (cs ContinuousSeries) GetName() string

GetName returns the name of the time series.

func (ContinuousSeries) GetStyle 

func (cs ContinuousSeries) GetStyle() Style

GetStyle returns the line style.

func (ContinuousSeries) GetValue 

func (cs ContinuousSeries) GetValue(index int) (float64, float64)

GetValue gets a value at a given index.

func (ContinuousSeries) GetValueFormatters 

func (cs ContinuousSeries) GetValueFormatters() (x, y ValueFormatter)

GetValueFormatters returns value formatter defaults for the series.

func (ContinuousSeries) GetYAxis 

func (cs ContinuousSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (ContinuousSeries) Len 

func (cs ContinuousSeries) Len() int

Len returns the number of elements in the series.

func (ContinuousSeries) Render 

func (cs ContinuousSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type EMASeries 

type EMASeries struct {
	Name  string
	Style Style
	YAxis YAxisType

	Period      int
	InnerSeries ValueProvider
	// contains filtered or unexported fields
}

EMASeries is a computed series.

func (*EMASeries) GetLastValue 

func (ema *EMASeries) GetLastValue() (x, y float64)

GetLastValue computes the last moving average value but walking back window size samples, and recomputing the last moving average chunk.

func (EMASeries) GetName 

func (ema EMASeries) GetName() string

GetName returns the name of the time series.

func (EMASeries) GetPeriod 

func (ema EMASeries) GetPeriod() int

GetPeriod returns the window size.

func (EMASeries) GetSigma 

func (ema EMASeries) GetSigma() float64

GetSigma returns the smoothing factor for the serise.

func (EMASeries) GetStyle 

func (ema EMASeries) GetStyle() Style

GetStyle returns the line style.

func (*EMASeries) GetValue 

func (ema *EMASeries) GetValue(index int) (x, y float64)

GetValue gets a value at a given index.

func (EMASeries) GetYAxis 

func (ema EMASeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (EMASeries) Len 

func (ema EMASeries) Len() int

Len returns the number of elements in the series.

func (*EMASeries) Render 

func (ema *EMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type Float 

type Float float64

Float is an alias for float64 that provides a better .String() method.

func (Float) String 

func (f Float) String() string

String returns the string representation of a float.

type FullBoundedValueProvider 

type FullBoundedValueProvider interface {
	BoundedValueProvider
	BoundedLastValueProvider
}

FullBoundedValueProvider is an interface that combines `BoundedValueProvider` and `BoundedLastValueProvider`

type FullValueProvider 

type FullValueProvider interface {
	ValueProvider
	LastValueProvider
}

FullValueProvider is an interface that combines `ValueProvider` and `LastValueProvider`

type GridLine 

type GridLine struct {
	IsMinor    bool
	IsVertical bool
	Style      Style
	Value      float64
}

GridLine is a line on a graph canvas.

func GenerateGridLines 

func GenerateGridLines(ticks []Tick, isVertical bool) []GridLine

GenerateGridLines generates grid lines.

func (GridLine) Horizontal 

func (gl GridLine) Horizontal() bool

Horizontal returns if the line is horizontal line or not.

func (GridLine) Major 

func (gl GridLine) Major() bool

Major returns if the gridline is a `major` line.

func (GridLine) Minor 

func (gl GridLine) Minor() bool

Minor returns if the gridline is a `minor` line.

func (GridLine) Render 

func (gl GridLine) Render(r Renderer, canvasBox Box, ra Range)

Render renders the gridline

func (GridLine) Vertical 

func (gl GridLine) Vertical() bool

Vertical returns if the line is vertical line or not.

type HistogramSeries 

type HistogramSeries struct {
	Name        string
	Style       Style
	YAxis       YAxisType
	InnerSeries ValueProvider
}

HistogramSeries is a special type of series that draws as a histogram. Some peculiarities; it will always be lower bounded at 0 (at the very least). This may alter ranges a bit and generally you want to put a histogram series on it's own y-axis.

func (HistogramSeries) GetBoundedValue 

func (hs HistogramSeries) GetBoundedValue(index int) (x, y1, y2 float64)

GetBoundedValue implements BoundedValueProvider.GetBoundedValue

func (HistogramSeries) GetName 

func (hs HistogramSeries) GetName() string

GetName implements Series.GetName.

func (HistogramSeries) GetStyle 

func (hs HistogramSeries) GetStyle() Style

GetStyle implements Series.GetStyle.

func (HistogramSeries) GetValue 

func (hs HistogramSeries) GetValue(index int) (x, y float64)

GetValue implements ValueProvider.GetValue.

func (HistogramSeries) GetYAxis 

func (hs HistogramSeries) GetYAxis() YAxisType

GetYAxis returns which yaxis the series is mapped to.

func (HistogramSeries) Len 

func (hs HistogramSeries) Len() int

Len implements BoundedValueProvider.Len.

func (HistogramSeries) Render 

func (hs HistogramSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render implements Series.Render.

type LastValueProvider 

type LastValueProvider interface {
	GetLastValue() (x, y float64)
}

LastValueProvider is a special type of value provider that can return it's (potentially computed) last value.

type MACDLineSeries 

type MACDLineSeries struct {
	Name        string
	Style       Style
	YAxis       YAxisType
	InnerSeries ValueProvider

	PrimaryPeriod   int
	SecondaryPeriod int

	Sigma float64
	// contains filtered or unexported fields
}

MACDLineSeries is a series that computes the inner ema1-ema2 value as a series.

func (MACDLineSeries) GetName 

func (macdl MACDLineSeries) GetName() string

GetName returns the name of the time series.

func (MACDLineSeries) GetPeriods 

func (macdl MACDLineSeries) GetPeriods() (w1, w2 int)

GetPeriods returns the primary and secondary periods.

func (MACDLineSeries) GetStyle 

func (macdl MACDLineSeries) GetStyle() Style

GetStyle returns the line style.

func (*MACDLineSeries) GetValue 

func (macdl *MACDLineSeries) GetValue(index int) (x float64, y float64)

GetValue gets a value at a given index. For MACD it is the signal value.

func (MACDLineSeries) GetYAxis 

func (macdl MACDLineSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (*MACDLineSeries) Len 

func (macdl *MACDLineSeries) Len() int

Len returns the number of elements in the series.

func (*MACDLineSeries) Render 

func (macdl *MACDLineSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type MACDSeries 

type MACDSeries struct {
	Name        string
	Style       Style
	YAxis       YAxisType
	InnerSeries ValueProvider

	PrimaryPeriod   int
	SecondaryPeriod int
	SignalPeriod    int
	// contains filtered or unexported fields
}

MACDSeries computes the difference between the MACD line and the MACD Signal line. It is used in technical analysis and gives a lagging indicator of momentum.

func (MACDSeries) GetName 

func (macd MACDSeries) GetName() string

GetName returns the name of the time series.

func (MACDSeries) GetPeriods 

func (macd MACDSeries) GetPeriods() (w1, w2, sig int)

GetPeriods returns the primary and secondary periods.

func (MACDSeries) GetStyle 

func (macd MACDSeries) GetStyle() Style

GetStyle returns the line style.

func (*MACDSeries) GetValue 

func (macd *MACDSeries) GetValue(index int) (x float64, y float64)

GetValue gets a value at a given index. For MACD it is the signal value.

func (MACDSeries) GetYAxis 

func (macd MACDSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (MACDSeries) Len 

func (macd MACDSeries) Len() int

Len returns the number of elements in the series.

type MACDSignalSeries 

type MACDSignalSeries struct {
	Name        string
	Style       Style
	YAxis       YAxisType
	InnerSeries ValueProvider

	PrimaryPeriod   int
	SecondaryPeriod int
	SignalPeriod    int
	// contains filtered or unexported fields
}

MACDSignalSeries computes the EMA of the MACDLineSeries.

func (MACDSignalSeries) GetName 

func (macds MACDSignalSeries) GetName() string

GetName returns the name of the time series.

func (MACDSignalSeries) GetPeriods 

func (macds MACDSignalSeries) GetPeriods() (w1, w2, sig int)

GetPeriods returns the primary and secondary periods.

func (MACDSignalSeries) GetStyle 

func (macds MACDSignalSeries) GetStyle() Style

GetStyle returns the line style.

func (*MACDSignalSeries) GetValue 

func (macds *MACDSignalSeries) GetValue(index int) (x float64, y float64)

GetValue gets a value at a given index. For MACD it is the signal value.

func (MACDSignalSeries) GetYAxis 

func (macds MACDSignalSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (*MACDSignalSeries) Len 

func (macds *MACDSignalSeries) Len() int

Len returns the number of elements in the series.

func (*MACDSignalSeries) Render 

func (macds *MACDSignalSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type Range 

type Range struct {
	Min    float64
	Max    float64
	Domain int
}

Range represents a boundary for a set of numbers.

func (Range) Delta 

func (r Range) Delta() float64

Delta returns the difference between the min and max value.

func (Range) GetRoundedRangeBounds 

func (r Range) GetRoundedRangeBounds() (min, max float64)

GetRoundedRangeBounds returns some `prettified` range bounds.

func (Range) IsZero 

func (r Range) IsZero() bool

IsZero returns if the range has been set or not.

func (Range) String 

func (r Range) String() string

String returns a simple string for the range.

func (Range) Translate 

func (r Range) Translate(value float64) int

Translate maps a given value into the range space.

type Renderable 

type Renderable func(r Renderer, canvasBox Box, defaults Style)

Renderable is a function that can be called to render custom elements on the chart.

func CreateLegend 

func CreateLegend(c *Chart, userDefaults ...Style) Renderable

CreateLegend returns a legend renderable function.

type Renderer 

type Renderer interface {
	// GetDPI gets the DPI for the renderer.
	GetDPI() float64

	// SetDPI sets the DPI for the renderer.
	SetDPI(dpi float64)

	// SetStrokeColor sets the current stroke color.
	SetStrokeColor(drawing.Color)

	// SetFillColor sets the current fill color.
	SetFillColor(drawing.Color)

	// SetStrokeWidth sets the stroke width.
	SetStrokeWidth(width float64)

	// SetStrokeDashArray sets the stroke dash array.
	SetStrokeDashArray(dashArray []float64)

	// MoveTo moves the cursor to a given point.
	MoveTo(x, y int)

	// LineTo both starts a shape and draws a line to a given point
	// from the previous point.
	LineTo(x, y int)

	// Close finalizes a shape as drawn by LineTo.
	Close()

	// Stroke strokes the path.
	Stroke()

	// Fill fills the path, but does not stroke.
	Fill()

	// FillStroke fills and strokes a path.
	FillStroke()

	// Circle draws a circle at the given coords with a given radius.
	Circle(radius float64, x, y int)

	// SetFont sets a font for a text field.
	SetFont(*truetype.Font)

	// SetFontColor sets a font's color
	SetFontColor(drawing.Color)

	// SetFontSize sets the font size for a text field.
	SetFontSize(size float64)

	// Text draws a text blob.
	Text(body string, x, y int)

	// MeasureText measures text.
	MeasureText(body string) Box

	// Save writes the image to the given writer.
	Save(w io.Writer) error
}

Renderer represents the basic methods required to draw a chart.

func PNG 

func PNG(width, height int) (Renderer, error)

PNG returns a new png/raster renderer.

func SVG 

func SVG(width, height int) (Renderer, error)

SVG returns a new png/raster renderer.

type RendererProvider 

type RendererProvider func(int, int) (Renderer, error)

RendererProvider is a function that returns a renderer.

type RingBuffer 

type RingBuffer struct {
	// contains filtered or unexported fields
}

RingBuffer is a fifo buffer that is backed by a pre-allocated array, instead of allocating a whole new node object for each element (which saves GC churn). Enqueue can be O(n), Dequeue can be O(1).

func NewRingBuffer 

func NewRingBuffer() *RingBuffer

NewRingBuffer creates a new, empty, RingBuffer.

func NewRingBufferFromSlice 

func NewRingBufferFromSlice(values []interface{}) *RingBuffer

NewRingBufferFromSlice createsa ring buffer out of a slice.

func NewRingBufferWithCapacity 

func NewRingBufferWithCapacity(capacity int) *RingBuffer

NewRingBufferWithCapacity creates a new RingBuffer pre-allocated with the given capacity.

func (*RingBuffer) AsSlice 

func (rb *RingBuffer) AsSlice() []interface{}

AsSlice returns the ring buffer, in order, as a slice.

func (*RingBuffer) Clear 

func (rb *RingBuffer) Clear()

Clear removes all objects from the RingBuffer.

func (*RingBuffer) Dequeue 

func (rb *RingBuffer) Dequeue() interface{}

Dequeue removes the first element from the RingBuffer.

func (*RingBuffer) Each 

func (rb *RingBuffer) Each(consumer func(value interface{}))

Each calls the consumer for each element in the buffer.

func (*RingBuffer) Enqueue 

func (rb *RingBuffer) Enqueue(object interface{})

Enqueue adds an element to the "back" of the RingBuffer.

func (*RingBuffer) Len 

func (rb *RingBuffer) Len() int

Len returns the length of the ring buffer (as it is currently populated). Actual memory footprint may be different.

func (*RingBuffer) Peek 

func (rb *RingBuffer) Peek() interface{}

Peek returns but does not remove the first element.

func (*RingBuffer) PeekBack 

func (rb *RingBuffer) PeekBack() interface{}

PeekBack returns but does not remove the last element.

func (*RingBuffer) String 

func (rb *RingBuffer) String() string

func (*RingBuffer) TotalLen 

func (rb *RingBuffer) TotalLen() int

TotalLen returns the total size of the ring bufffer, including empty elements.

func (*RingBuffer) TrimExcess 

func (rb *RingBuffer) TrimExcess()

TrimExcess resizes the buffer to better fit the contents.

type SMASeries 

type SMASeries struct {
	Name  string
	Style Style
	YAxis YAxisType

	Period      int
	InnerSeries ValueProvider
}

SMASeries is a computed series.

func (SMASeries) GetLastValue 

func (sma SMASeries) GetLastValue() (x, y float64)

GetLastValue computes the last moving average value but walking back window size samples, and recomputing the last moving average chunk.

func (SMASeries) GetName 

func (sma SMASeries) GetName() string

GetName returns the name of the time series.

func (SMASeries) GetPeriod 

func (sma SMASeries) GetPeriod(defaults ...int) int

GetPeriod returns the window size.

func (SMASeries) GetStyle 

func (sma SMASeries) GetStyle() Style

GetStyle returns the line style.

func (SMASeries) GetValue 

func (sma SMASeries) GetValue(index int) (x, y float64)

GetValue gets a value at a given index.

func (SMASeries) GetYAxis 

func (sma SMASeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (SMASeries) Len 

func (sma SMASeries) Len() int

Len returns the number of elements in the series.

func (SMASeries) Render 

func (sma SMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type Series 

type Series interface {
	GetName() string
	GetYAxis() YAxisType
	GetStyle() Style
	Render(r Renderer, canvasBox Box, xrange, yrange Range, s Style)
}

Series is an alias to Renderable.

type Style 

type Style struct {
	Show    bool
	Padding Box

	StrokeWidth     float64
	StrokeColor     drawing.Color
	StrokeDashArray []float64

	FillColor drawing.Color
	FontSize  float64
	FontColor drawing.Color
	Font      *truetype.Font
}

Style is a simple style set.

func (Style) GetFillColor 

func (s Style) GetFillColor(defaults ...drawing.Color) drawing.Color

GetFillColor returns the fill color.

func (Style) GetFont 

func (s Style) GetFont(defaults ...*truetype.Font) *truetype.Font

GetFont returns the font face.

func (Style) GetFontColor 

func (s Style) GetFontColor(defaults ...drawing.Color) drawing.Color

GetFontColor gets the font size.

func (Style) GetFontSize 

func (s Style) GetFontSize(defaults ...float64) float64

GetFontSize gets the font size.

func (Style) GetPadding 

func (s Style) GetPadding(defaults ...Box) Box

GetPadding returns the padding.

func (Style) GetStrokeColor 

func (s Style) GetStrokeColor(defaults ...drawing.Color) drawing.Color

GetStrokeColor returns the stroke color.

func (Style) GetStrokeDashArray 

func (s Style) GetStrokeDashArray(defaults ...[]float64) []float64

GetStrokeDashArray returns the stroke dash array.

func (Style) GetStrokeWidth 

func (s Style) GetStrokeWidth(defaults ...float64) float64

GetStrokeWidth returns the stroke width.

func (Style) IsZero 

func (s Style) IsZero() bool

IsZero returns if the object is set or not.

func (Style) SVG 

func (s Style) SVG(dpi float64) string

SVG returns the style as a svg style string.

func (Style) SVGFill 

func (s Style) SVGFill() Style

SVGFill returns the fill components.

func (Style) SVGFillAndStroke 

func (s Style) SVGFillAndStroke() Style

SVGFillAndStroke returns the fill and stroke components.

func (Style) SVGFontFace 

func (s Style) SVGFontFace() string

SVGFontFace returns the font face for the style.

func (Style) SVGStroke 

func (s Style) SVGStroke() Style

SVGStroke returns the stroke components.

func (Style) SVGStrokeDashArray 

func (s Style) SVGStrokeDashArray() string

SVGStrokeDashArray returns the stroke-dasharray property of a style.

func (Style) SVGText 

func (s Style) SVGText() Style

SVGText returns just the text components of the style.

func (Style) String 

func (s Style) String() string

func (Style) WithDefaultsFrom 

func (s Style) WithDefaultsFrom(defaults Style) (final Style)

WithDefaultsFrom coalesces two styles into a new style.

type Tick 

type Tick struct {
	Value float64
	Label string
}

Tick represents a label on an axis.

func GenerateTicksWithStep 

func GenerateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick

GenerateTicksWithStep generates a set of ticks.

type Ticks 

type Ticks []Tick

Ticks is an array of ticks.

func (Ticks) Len 

func (t Ticks) Len() int

Len returns the length of the ticks set.

func (Ticks) Less 

func (t Ticks) Less(i, j int) bool

Less returns if i's value is less than j's value.

func (Ticks) Swap 

func (t Ticks) Swap(i, j int)

Swap swaps two elements.

type TimeSeries 

type TimeSeries struct {
	Name  string
	Style Style

	YAxis YAxisType

	XValues []time.Time
	YValues []float64
}

TimeSeries is a line on a chart.

func (TimeSeries) GetLastValue 

func (ts TimeSeries) GetLastValue() (x, y float64)

GetLastValue gets the last value.

func (TimeSeries) GetName 

func (ts TimeSeries) GetName() string

GetName returns the name of the time series.

func (TimeSeries) GetStyle 

func (ts TimeSeries) GetStyle() Style

GetStyle returns the line style.

func (TimeSeries) GetValue 

func (ts TimeSeries) GetValue(index int) (x, y float64)

GetValue gets a value at a given index.

func (TimeSeries) GetValueFormatters 

func (ts TimeSeries) GetValueFormatters() (x, y ValueFormatter)

GetValueFormatters returns value formatter defaults for the series.

func (TimeSeries) GetYAxis 

func (ts TimeSeries) GetYAxis() YAxisType

GetYAxis returns which YAxis the series draws on.

func (TimeSeries) Len 

func (ts TimeSeries) Len() int

Len returns the number of elements in the series.

func (TimeSeries) Render 

func (ts TimeSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style)

Render renders the series.

type ValueFormatter 

type ValueFormatter func(v interface{}) string

ValueFormatter is a function that takes a value and produces a string.

type ValueFormatterProvider 

type ValueFormatterProvider interface {
	GetValueFormatters() (x, y ValueFormatter)
}

ValueFormatterProvider is a series that has custom formatters.

type ValueProvider 

type ValueProvider interface {
	Len() int
	GetValue(index int) (float64, float64)
}

ValueProvider is a type that produces values.

type XAxis 

type XAxis struct {
	Name           string
	Style          Style
	ValueFormatter ValueFormatter
	Range          Range
	Ticks          []Tick

	GridLines      []GridLine
	GridMajorStyle Style
	GridMinorStyle Style
}

XAxis represents the horizontal axis.

func (XAxis) GetGridLines 

func (xa XAxis) GetGridLines(ticks []Tick) []GridLine

GetGridLines returns the gridlines for the axis.

func (XAxis) GetName 

func (xa XAxis) GetName() string

GetName returns the name.

func (XAxis) GetStyle 

func (xa XAxis) GetStyle() Style

GetStyle returns the style.

func (XAxis) GetTicks 

func (xa XAxis) GetTicks(r Renderer, ra Range, defaults Style, vf ValueFormatter) []Tick

GetTicks returns the ticks for a series. It coalesces between user provided ticks and generated ticks.

func (XAxis) Measure 

func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) Box

Measure returns the bounds of the axis.

func (XAxis) Render 

func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick)

Render renders the axis

type YAxis 

type YAxis struct {
	Name  string
	Style Style

	Zero GridLine

	AxisType YAxisType

	ValueFormatter ValueFormatter
	Range          Range
	Ticks          []Tick

	GridLines      []GridLine
	GridMajorStyle Style
	GridMinorStyle Style
}

YAxis is a veritcal rule of the range. There can be (2) y-axes; a primary and secondary.

func (YAxis) GetGridLines 

func (ya YAxis) GetGridLines(ticks []Tick) []GridLine

GetGridLines returns the gridlines for the axis.

func (YAxis) GetName 

func (ya YAxis) GetName() string

GetName returns the name.

func (YAxis) GetStyle 

func (ya YAxis) GetStyle() Style

GetStyle returns the style.

func (YAxis) GetTicks 

func (ya YAxis) GetTicks(r Renderer, ra Range, defaults Style, vf ValueFormatter) []Tick

GetTicks returns the ticks for a series. It coalesces between user provided ticks and generated ticks.

func (YAxis) Measure 

func (ya YAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) Box

Measure returns the bounds of the axis.

func (YAxis) Render 

func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick)

Render renders the axis.

type YAxisType 

type YAxisType int

YAxisType is a type of y-axis; it can either be primary or secondary. 

const (
	// YAxisPrimary is the primary axis.
	YAxisPrimary YAxisType = 0
	// YAxisSecondary is the secondary axis.
	YAxisSecondary YAxisType = 1
)

Source Files

View all Source files

Directories

Path Synopsis
examples
annotations
axes
basic
custom_formatters
custom_padding
custom_ranges
custom_styles
custom_ticks
legend
response_times
simple_moving_average
stock_analysis
timeseries
twoaxis

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