mostly working

_examples/custom_padding/main.go

@@ -27,7 +27,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 		Series: []chart.Series{
 			chart.ContinuousSeries{
-				XValues: seq.Range(1.0, 100.0),
+				XValues: SeqRange(1.0, 100.0),
 				YValues: seq.RandomValuesWithMax(100, 512),
 			},
 		},
@@ -50,7 +50,7 @@ func drawChartDefault(res http.ResponseWriter, req *http.Request) {
 		},
 		Series: []chart.Series{
 			chart.ContinuousSeries{
-				XValues: seq.Range(1.0, 100.0),
+				XValues: SeqRange(1.0, 100.0),
 				YValues: seq.RandomValuesWithMax(100, 512),
 			},
 		},

_examples/linear_regression/main.go

@@ -16,7 +16,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	mainSeries := chart.ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
+		XValues: SeqRange(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
 		YValues: seq.RandomValuesWithMax(100, 100), //generates a []float64 randomly from 0 to 100 with 100 elements.
 	}
 

_examples/min_max/main.go

@@ -10,7 +10,7 @@ import (
 func drawChart(res http.ResponseWriter, req *http.Request) {
 	mainSeries := chart.ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(1.0, 100.0),
+		XValues: SeqRange(1.0, 100.0),
 		YValues: seq.New(seq.NewRandom().WithLen(100).WithMax(150).WithMin(50)).Array(),
 	}
 

_examples/poly_regression/main.go

@@ -16,7 +16,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	mainSeries := chart.ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
+		XValues: SeqRange(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
 		YValues: seq.RandomValuesWithMax(100, 100), //generates a []float64 randomly from 0 to 100 with 100 elements.
 	}
 

_examples/request_timings/main.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"net/http"
 	"strconv"
-	"strings"
 	"time"
 
 	chart "github.com/wcharczuk/go-chart"
@@ -24,7 +23,7 @@ func readData() ([]time.Time, []float64) {
 	var xvalues []time.Time
 	var yvalues []float64
 	err := chart.ReadLines("requests.csv", func(line string) error {
-		parts := strings.Split(line, ",")
+		parts := chart.SplitCSV(line)
 		year := parseInt(parts[0])
 		month := parseInt(parts[1])
 		day := parseInt(parts[2])
@@ -51,12 +50,12 @@ func releases() []chart.GridLine {
 	}
 }
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func drawChart(log chart.Logger) http.HandlerFunc {
+	return func(res http.ResponseWriter, req *http.Request) {
 		xvalues, yvalues := readData()
 		mainSeries := chart.TimeSeries{
 			Name: "Prod Request Timings",
 			Style: chart.Style{
-			Show:        true,
 				StrokeColor: chart.ColorBlue,
 				FillColor:   chart.ColorBlue.WithAlpha(100),
 			},
@@ -67,7 +66,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		linreg := &chart.LinearRegressionSeries{
 			Name: "Linear Regression",
 			Style: chart.Style{
-			Show:            true,
 				StrokeColor:     chart.ColorAlternateBlue,
 				StrokeDashArray: []float64{5.0, 5.0},
 			},
@@ -77,7 +75,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		sma := &chart.SMASeries{
 			Name: "SMA",
 			Style: chart.Style{
-			Show:            true,
 				StrokeColor:     chart.ColorRed,
 				StrokeDashArray: []float64{5.0, 5.0},
 			},
@@ -85,6 +82,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		}
 
 		graph := chart.Chart{
+			Log:    log,
 			Width:  1280,
 			Height: 720,
 			Background: chart.Style{
@@ -94,8 +92,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			},
 			YAxis: chart.YAxis{
 				Name: "Elapsed Millis",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
 				TickStyle: chart.Style{
 					TextRotationDegrees: 45.0,
 				},
@@ -104,10 +100,8 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 				},
 			},
 			XAxis: chart.XAxis{
-			Style:          chart.StyleShow(),
 				ValueFormatter: chart.TimeHourValueFormatter,
 				GridMajorStyle: chart.Style{
-				Show:        true,
 					StrokeColor: chart.ColorAlternateGray,
 					StrokeWidth: 1.0,
 				},
@@ -125,10 +119,15 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		graph.Elements = []chart.Renderable{chart.LegendThin(&graph)}
 
 		res.Header().Set("Content-Type", chart.ContentTypePNG)
-	graph.Render(chart.PNG, res)
+		if err := graph.Render(chart.PNG, res); err != nil {
+			log.Err(err)
+		}
+	}
 }
 
 func main() {
-	http.HandleFunc("/", drawChart)
+	log := chart.NewLogger()
+	log.Infof("listening on :8080")
+	http.HandleFunc("/", drawChart(log))
 	http.ListenAndServe(":8080", nil)
 }

_examples/scatter/main.go

@@ -6,9 +6,8 @@ import (
 
 	_ "net/http/pprof"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 	"github.com/wcharczuk/go-chart/drawing"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {
@@ -26,8 +25,8 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 					DotWidth:         5,
 					DotColorProvider: viridisByY,
 				},
-				XValues: seq.Range(0, 127),
+				XValues: chart.SeqRange(0, 127),
-				YValues: seq.New(seq.NewRandom().WithLen(128).WithMax(1024)).Array(),
+				YValues: chart.NewSeq(chart.NewSeqRandom().WithLen(128).WithMax(1024)).Values(),
 			},
 		},
 	}
@@ -51,8 +50,8 @@ func unit(res http.ResponseWriter, req *http.Request) {
 		},
 		Series: []chart.Series{
 			chart.ContinuousSeries{
-				XValues: seq.RangeWithStep(0, 4, 1),
+				XValues: chart.SeqRangeWithStep(0, 4, 1),
-				YValues: seq.RangeWithStep(0, 4, 1),
+				YValues: chart.SeqRangeWithStep(0, 4, 1),
 			},
 		},
 	}

_examples/simple_moving_average/main.go

@@ -3,16 +3,15 @@ package main
 import (
 	"net/http"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	mainSeries := chart.ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
+		XValues: chart.SeqRange(1.0, 100.0),             //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
-		YValues: seq.RandomValuesWithMax(100, 100), //generates a []float64 randomly from 0 to 100 with 100 elements.
+		YValues: chart.SeqRandomValuesWithMax(100, 100), //generates a []float64 randomly from 0 to 100 with 100 elements.
 	}
 
 	// note we create a SimpleMovingAverage series by assignin the inner series.

_examples/stacked_bar/main.go

@@ -5,7 +5,7 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {

_examples/stock_analysis/main.go

@@ -4,7 +4,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 	"github.com/wcharczuk/go-chart/drawing"
 )
 

_examples/text_rotation/main.go

@@ -3,7 +3,7 @@ package main
 import (
 	"net/http"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 	"github.com/wcharczuk/go-chart/drawing"
 )
 

_examples/timeseries/main.go

@@ -4,7 +4,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {

_examples/twoaxis/main.go

@@ -4,8 +4,7 @@ import (
 	"fmt"
 	"net/http"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
-	util "github.com/wcharczuk/go-chart/util"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {
@@ -22,7 +21,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			TickPosition: chart.TickPositionBetweenTicks,
 			ValueFormatter: func(v interface{}) string {
 				typed := v.(float64)
-				typedDate := util.Time.FromFloat64(typed)
+				typedDate := chart.TimeFromFloat64(typed)
 				return fmt.Sprintf("%d-%d\n%d", typedDate.Month(), typedDate.Day(), typedDate.Year())
 			},
 		},

_examples/twopoint/main.go

@@ -5,7 +5,7 @@ import (
 	"log"
 	"os"
 
-	"github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart"
 )
 
 func main() {

annotation_series.go

@@ -53,7 +53,7 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 		Right:  0,
 		Bottom: 0,
 	}
-	if as.Style.IsZero() || as.Style.Show {
+	if !as.Style.Hidden {
 		seriesStyle := as.Style.InheritFrom(as.annotationStyleDefaults(defaults))
 		for _, a := range as.Annotations {
 			style := a.Style.InheritFrom(seriesStyle)
@@ -71,7 +71,7 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 
 // Render draws the series.
 func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	if as.Style.IsZero() || as.Style.Show {
+	if !as.Style.Hidden {
 		seriesStyle := as.Style.InheritFrom(as.annotationStyleDefaults(defaults))
 		for _, a := range as.Annotations {
 			style := a.Style.InheritFrom(seriesStyle)

annotation_series_test.go

@@ -13,7 +13,6 @@ func TestAnnotationSeriesMeasure(t *testing.T) {
 	assert := assert.New(t)
 
 	as := AnnotationSeries{
-		Style: StyleShow(),
 		Annotations: []Value2{
 			{XValue: 1.0, YValue: 1.0, Label: "1.0"},
 			{XValue: 2.0, YValue: 2.0, Label: "2.0"},
@@ -63,7 +62,6 @@ func TestAnnotationSeriesRender(t *testing.T) {
 
 	as := AnnotationSeries{
 		Style: Style{
-			Show:        true,
 			FillColor:   drawing.ColorWhite,
 			StrokeColor: drawing.ColorBlack,
 		},

array.go

@@ -0,0 +1,24 @@
+package chart
+
+var (
+	_ Sequence = (*Array)(nil)
+)
+
+// NewArray returns a new array from a given set of values.
+// Array implements Sequence, which allows it to be used with the sequence helpers.
+func NewArray(values ...float64) Array {
+	return Array(values)
+}
+
+// Array is a wrapper for an array of floats that implements `ValuesProvider`.
+type Array []float64
+
+// Len returns the value provider length.
+func (a Array) Len() int {
+	return len(a)
+}
+
+// GetValue returns the value at a given index.
+func (a Array) GetValue(index int) float64 {
+	return a[index]
+}

bar_chart.go

@@ -224,7 +224,7 @@ func (bc BarChart) drawBars(r Renderer, canvasBox Box, yr Range) {
 }
 
 func (bc BarChart) drawXAxis(r Renderer, canvasBox Box) {
-	if bc.XAxis.Show {
+	if !bc.XAxis.Hidden {
 		axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes())
 		axisStyle.WriteToRenderer(r)
 
@@ -263,7 +263,7 @@ func (bc BarChart) drawXAxis(r Renderer, canvasBox Box) {
 }
 
 func (bc BarChart) drawYAxis(r Renderer, canvasBox Box, yr Range, ticks []Tick) {
-	if bc.YAxis.Style.Show {
+	if !bc.YAxis.Style.Hidden {
 		axisStyle := bc.YAxis.Style.InheritFrom(bc.styleDefaultsAxes())
 		axisStyle.WriteToRenderer(r)
 
@@ -294,7 +294,7 @@ func (bc BarChart) drawYAxis(r Renderer, canvasBox Box, yr Range, ticks []Tick)
 }
 
 func (bc BarChart) drawTitle(r Renderer) {
-	if len(bc.Title) > 0 && bc.TitleStyle.Show {
+	if len(bc.Title) > 0 && !bc.TitleStyle.Hidden {
 		r.SetFont(bc.TitleStyle.GetFont(bc.GetFont()))
 		r.SetFontColor(bc.TitleStyle.GetFontColor(bc.GetColorPalette().TextColor()))
 		titleFontSize := bc.TitleStyle.GetFontSize(bc.getTitleFontSize())
@@ -325,7 +325,7 @@ func (bc BarChart) styleDefaultsCanvas() Style {
 }
 
 func (bc BarChart) hasAxes() bool {
-	return bc.YAxis.Style.Show
+	return !bc.YAxis.Style.Hidden
 }
 
 func (bc BarChart) setRangeDomains(canvasBox Box, yr Range) Range {
@@ -345,7 +345,7 @@ func (bc BarChart) getValueFormatters() ValueFormatter {
 }
 
 func (bc BarChart) getAxesTicks(r Renderer, yr Range, yf ValueFormatter) (yticks []Tick) {
-	if bc.YAxis.Style.Show {
+	if !bc.YAxis.Style.Hidden {
 		yticks = bc.YAxis.GetTicks(r, yr, bc.styleDefaultsAxes(), yf)
 	}
 	return
@@ -391,7 +391,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 
 	_, _, totalWidth := bc.calculateScaledTotalWidth(canvasBox)
 
-	if bc.XAxis.Show {
+	if !bc.XAxis.Hidden {
 		xaxisHeight := DefaultVerticalTickHeight
 
 		axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes())
@@ -423,7 +423,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 		axesOuterBox = axesOuterBox.Grow(xbox)
 	}
 
-	if bc.YAxis.Style.Show {
+	if !bc.YAxis.Style.Hidden {
 		axesBounds := bc.YAxis.Measure(r, canvasBox, yrange, bc.styleDefaultsAxes(), yticks)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}

bar_chart_test.go

@@ -14,11 +14,6 @@ func TestBarChartRender(t *testing.T) {
 	bc := BarChart{
 		Width: 1024,
 		Title: "Test Title",
-		TitleStyle: StyleShow(),
-		XAxis:      StyleShow(),
-		YAxis: YAxis{
-			Style: StyleShow(),
-		},
 		Bars: []Value{
 			{Value: 1.0, Label: "One"},
 			{Value: 2.0, Label: "Two"},
@@ -40,11 +35,6 @@ func TestBarChartRenderZero(t *testing.T) {
 	bc := BarChart{
 		Width: 1024,
 		Title: "Test Title",
-		TitleStyle: StyleShow(),
-		XAxis:      StyleShow(),
-		YAxis: YAxis{
-			Style: StyleShow(),
-		},
 		Bars: []Value{
 			{Value: 0.0, Label: "One"},
 			{Value: 0.0, Label: "Two"},
@@ -183,12 +173,11 @@ func TestBarChartHasAxes(t *testing.T) {
 	assert := assert.New(t)
 
 	bc := BarChart{}
-	assert.False(bc.hasAxes())
-	bc.YAxis = YAxis{
-		Style: StyleShow(),
-	}
-
 	assert.True(bc.hasAxes())
+	bc.YAxis = YAxis{
+		Style: Hidden(),
+	}
+	assert.False(bc.hasAxes())
 }
 
 func TestBarChartGetDefaultCanvasBox(t *testing.T) {
@@ -237,10 +226,11 @@ func TestBarChartGetAxesTicks(t *testing.T) {
 	yr := bc.getRanges()
 	yf := bc.getValueFormatters()
 
+	bc.YAxis.Style.Hidden = true
 	ticks := bc.getAxesTicks(r, yr, yf)
 	assert.Empty(ticks)
 
-	bc.YAxis.Style.Show = true
+	bc.YAxis.Style.Hidden = false
 	ticks = bc.getAxesTicks(r, yr, yf)
 	assert.Len(ticks, 2)
 }

bollinger_band_series.go

@@ -79,8 +79,8 @@ func (bbs *BollingerBandsSeries) GetBoundedValues(index int) (x, y1, y2 float64)
 	bbs.valueBuffer.Enqueue(py)
 	x = px
 
-	ay := NewSeq(bbs.valueBuffer).Average()
+	ay := Seq{bbs.valueBuffer}.Average()
-	std := NewSeq(bbs.valueBuffer).StdDev()
+	std := Seq{bbs.valueBuffer}.StdDev()
 
 	y1 = ay + (bbs.GetK() * std)
 	y2 = ay - (bbs.GetK() * std)

bollinger_band_series_test.go

@@ -12,8 +12,8 @@ func TestBollingerBandSeries(t *testing.T) {
 	assert := assert.New(t)
 
 	s1 := mockValuesProvider{
-		X: SeqRange(1.0, 100.0),
+		X: LinearRange(1.0, 100.0),
-		Y: SeqRandomValuesWithMax(100, 1024),
+		Y: RandomValuesWithMax(100, 1024),
 	}
 
 	bbs := &BollingerBandsSeries{
@@ -37,8 +37,8 @@ func TestBollingerBandLastValue(t *testing.T) {
 	assert := assert.New(t)
 
 	s1 := mockValuesProvider{
-		X: SeqRange(1.0, 100.0),
+		X: LinearRange(1.0, 100.0),
-		Y: SeqRange(1.0, 100.0),
+		Y: LinearRange(1.0, 100.0),
 	}
 
 	bbs := &BollingerBandsSeries{

chart.go

@@ -32,6 +32,8 @@ type Chart struct {
 
 	Series   []Series
 	Elements []Renderable
+
+	Log Logger
 }
 
 // GetDPI returns the dpi for the chart.
@@ -74,8 +76,8 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 	if len(c.Series) == 0 {
 		return errors.New("please provide at least one series")
 	}
-	if visibleSeriesErr := c.checkHasVisibleSeries(); visibleSeriesErr != nil {
+	if err := c.checkHasVisibleSeries(); err != nil {
-		return visibleSeriesErr
+		return err
 	}
 
 	c.YAxisSecondary.AxisType = YAxisSecondary
@@ -142,17 +144,15 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 }
 
 func (c Chart) checkHasVisibleSeries() error {
-	hasVisibleSeries := false
 	var style Style
 	for _, s := range c.Series {
 		style = s.GetStyle()
-		hasVisibleSeries = hasVisibleSeries || (style.IsZero() || style.Show)
+		if !style.Hidden {
-	}
-	if !hasVisibleSeries {
-		return fmt.Errorf("must have (1) visible series; make sure if you set a style, you set .Show = true")
-	}
 			return nil
 		}
+	}
+	return fmt.Errorf("chart render; must have (1) visible series")
+}
 
 func (c Chart) validateSeries() error {
 	var err error
@@ -175,7 +175,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 	// note: a possible future optimization is to not scan the series values if
 	// all axis are represented by either custom ticks or custom ranges.
 	for _, s := range c.Series {
-		if s.GetStyle().IsZero() || s.GetStyle().Show {
+		if !s.GetStyle().Hidden {
 			seriesAxis := s.GetYAxis()
 			if bvp, isBoundedValuesProvider := s.(BoundedValuesProvider); isBoundedValuesProvider {
 				seriesLength := bvp.Len()
@@ -262,8 +262,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 		yrange.SetMin(miny)
 		yrange.SetMax(maxy)
 
-		// only round if we're showing the axis
+		if !c.YAxis.Style.Hidden {
-		if c.YAxis.Style.Show {
 			delta := yrange.GetDelta()
 			roundTo := GetRoundToForDelta(delta)
 			rmin, rmax := RoundDown(yrange.GetMin(), roundTo), RoundUp(yrange.GetMax(), roundTo)
@@ -285,7 +284,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 		yrangeAlt.SetMin(minya)
 		yrangeAlt.SetMax(maxya)
 
-		if c.YAxisSecondary.Style.Show {
+		if !c.YAxisSecondary.Style.Hidden {
 			delta := yrangeAlt.GetDelta()
 			roundTo := GetRoundToForDelta(delta)
 			rmin, rmax := RoundDown(yrangeAlt.GetMin(), roundTo), RoundUp(yrangeAlt.GetMax(), roundTo)
@@ -298,6 +297,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 }
 
 func (c Chart) checkRanges(xr, yr, yra Range) error {
+	Debugf(c.Log, "checking xrange: %v", xr)
 	xDelta := xr.GetDelta()
 	if math.IsInf(xDelta, 0) {
 		return errors.New("infinite x-range delta")
@@ -309,6 +309,7 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 		return errors.New("zero x-range delta; there needs to be at least (2) values")
 	}
 
+	Debugf(c.Log, "checking yrange: %v", yr)
 	yDelta := yr.GetDelta()
 	if math.IsInf(yDelta, 0) {
 		return errors.New("infinite y-range delta")
@@ -318,6 +319,7 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 	}
 
 	if c.hasSecondarySeries() {
+		Debugf(c.Log, "checking secondary yrange: %v", yra)
 		yraDelta := yra.GetDelta()
 		if math.IsInf(yraDelta, 0) {
 			return errors.New("infinite secondary y-range delta")
@@ -360,17 +362,17 @@ func (c Chart) getValueFormatters() (x, y, ya ValueFormatter) {
 }
 
 func (c Chart) hasAxes() bool {
-	return c.XAxis.Style.Show || c.YAxis.Style.Show || c.YAxisSecondary.Style.Show
+	return !c.XAxis.Style.Hidden || !c.YAxis.Style.Hidden || !c.YAxisSecondary.Style.Hidden
 }
 
 func (c Chart) getAxesTicks(r Renderer, xr, yr, yar Range, xf, yf, yfa ValueFormatter) (xticks, yticks, yticksAlt []Tick) {
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		xticks = c.XAxis.GetTicks(r, xr, c.styleDefaultsAxes(), xf)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		yticks = c.YAxis.GetTicks(r, yr, c.styleDefaultsAxes(), yf)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden {
 		yticksAlt = c.YAxisSecondary.GetTicks(r, yar, c.styleDefaultsAxes(), yfa)
 	}
 	return
@@ -378,15 +380,15 @@ func (c Chart) getAxesTicks(r Renderer, xr, yr, yar Range, xf, yf, yfa ValueForm
 
 func (c Chart) getAxesAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr, yra Range, xticks, yticks, yticksAlt []Tick) Box {
 	axesOuterBox := canvasBox.Clone()
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		axesBounds := c.XAxis.Measure(r, canvasBox, xr, c.styleDefaultsAxes(), xticks)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		axesBounds := c.YAxis.Measure(r, canvasBox, yr, c.styleDefaultsAxes(), yticks)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden {
 		axesBounds := c.YAxisSecondary.Measure(r, canvasBox, yra, c.styleDefaultsAxes(), yticksAlt)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
@@ -404,7 +406,7 @@ func (c Chart) setRangeDomains(canvasBox Box, xr, yr, yra Range) (Range, Range,
 func (c Chart) hasAnnotationSeries() bool {
 	for _, s := range c.Series {
 		if as, isAnnotationSeries := s.(AnnotationSeries); isAnnotationSeries {
-			if as.Style.IsZero() || as.Style.Show {
+			if !as.GetStyle().Hidden {
 				return true
 			}
 		}
@@ -425,7 +427,7 @@ func (c Chart) getAnnotationAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr,
 	annotationSeriesBox := canvasBox.Clone()
 	for seriesIndex, s := range c.Series {
 		if as, isAnnotationSeries := s.(AnnotationSeries); isAnnotationSeries {
-			if as.Style.IsZero() || as.Style.Show {
+			if !as.GetStyle().Hidden {
 				style := c.styleDefaultsSeries(seriesIndex)
 				var annotationBounds Box
 				if as.YAxis == YAxisPrimary {
@@ -462,19 +464,19 @@ func (c Chart) drawCanvas(r Renderer, canvasBox Box) {
 }
 
 func (c Chart) drawAxes(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt Range, xticks, yticks, yticksAlt []Tick) {
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		c.XAxis.Render(r, canvasBox, xrange, c.styleDefaultsAxes(), xticks)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		c.YAxis.Render(r, canvasBox, yrange, c.styleDefaultsAxes(), yticks)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden {
 		c.YAxisSecondary.Render(r, canvasBox, yrangeAlt, c.styleDefaultsAxes(), yticksAlt)
 	}
 }
 
 func (c Chart) drawSeries(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt Range, s Series, seriesIndex int) {
-	if s.GetStyle().IsZero() || s.GetStyle().Show {
+	if !s.GetStyle().Hidden {
 		if s.GetYAxis() == YAxisPrimary {
 			s.Render(r, canvasBox, xrange, yrange, c.styleDefaultsSeries(seriesIndex))
 		} else if s.GetYAxis() == YAxisSecondary {
@@ -484,7 +486,7 @@ func (c Chart) drawSeries(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt R
 }
 
 func (c Chart) drawTitle(r Renderer) {
-	if len(c.Title) > 0 && c.TitleStyle.Show {
+	if len(c.Title) > 0 && !c.TitleStyle.Hidden {
 		r.SetFont(c.TitleStyle.GetFont(c.GetFont()))
 		r.SetFontColor(c.TitleStyle.GetFontColor(c.GetColorPalette().TextColor()))
 		titleFontSize := c.TitleStyle.GetFontSize(DefaultTitleFontSize)

chart_test.go

@@ -274,25 +274,44 @@ func TestChartGetValueFormatters(t *testing.T) {
 func TestChartHasAxes(t *testing.T) {
 	assert := assert.New(t)
 
-	assert.False(Chart{}.hasAxes())
+	assert.True(Chart{}.hasAxes())
+	assert.False(Chart{XAxis: XAxis{Style: Hidden()}, YAxis: YAxis{Style: Hidden()}, YAxisSecondary: YAxis{Style: Hidden()}}.hasAxes())
 
 	x := Chart{
 		XAxis: XAxis{
-			Style: StyleShow(),
+			Style: Hidden(),
+		},
+		YAxis: YAxis{
+			Style: Shown(),
+		},
+		YAxisSecondary: YAxis{
+			Style: Hidden(),
 		},
 	}
 	assert.True(x.hasAxes())
 
 	y := Chart{
+		XAxis: XAxis{
+			Style: Shown(),
+		},
 		YAxis: YAxis{
-			Style: StyleShow(),
+			Style: Hidden(),
+		},
+		YAxisSecondary: YAxis{
+			Style: Hidden(),
 		},
 	}
 	assert.True(y.hasAxes())
 
 	ya := Chart{
+		XAxis: XAxis{
+			Style: Hidden(),
+		},
+		YAxis: YAxis{
+			Style: Hidden(),
+		},
 		YAxisSecondary: YAxis{
-			Style: StyleShow(),
+			Style: Shown(),
 		},
 	}
 	assert.True(ya.hasAxes())
@@ -306,15 +325,12 @@ func TestChartGetAxesTicks(t *testing.T) {
 
 	c := Chart{
 		XAxis: XAxis{
-			Style: StyleShow(),
 			Range: &ContinuousRange{Min: 9.8, Max: 19.8},
 		},
 		YAxis: YAxis{
-			Style: StyleShow(),
 			Range: &ContinuousRange{Min: 9.9, Max: 19.9},
 		},
 		YAxisSecondary: YAxis{
-			Style: StyleShow(),
 			Range: &ContinuousRange{Min: 9.7, Max: 19.7},
 		},
 	}
@@ -331,19 +347,14 @@ func TestChartSingleSeries(t *testing.T) {
 	now := time.Now()
 	c := Chart{
 		Title:  "Hello!",
-		TitleStyle: StyleShow(),
 		Width:  1024,
 		Height: 400,
 		YAxis: YAxis{
-			Style: StyleShow(),
 			Range: &ContinuousRange{
 				Min: 0.0,
 				Max: 4.0,
 			},
 		},
-		XAxis: XAxis{
-			Style: StyleShow(),
-		},
 		Series: []Series{
 			TimeSeries{
 				Name:    "goog",
@@ -386,8 +397,8 @@ func TestChartRegressionBadRangesByUser(t *testing.T) {
 		},
 		Series: []Series{
 			ContinuousSeries{
-				XValues: SeqRange(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
-				YValues: SeqRange(1.0, 10.0),
+				YValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
@@ -402,8 +413,8 @@ func TestChartValidatesSeries(t *testing.T) {
 	c := Chart{
 		Series: []Series{
 			ContinuousSeries{
-				XValues: SeqRange(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
-				YValues: SeqRange(1.0, 10.0),
+				YValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
@@ -413,7 +424,7 @@ func TestChartValidatesSeries(t *testing.T) {
 	c = Chart{
 		Series: []Series{
 			ContinuousSeries{
-				XValues: SeqRange(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
@@ -483,8 +494,8 @@ func TestChartE2ELine(t *testing.T) {
 		},
 		Series: []Series{
 			ContinuousSeries{
-				XValues: seq.RangeWithStep(0, 4, 1),
+				XValues: LinearRangeWithStep(0, 4, 1),
-				YValues: seq.RangeWithStep(0, 4, 1),
+				YValues: LinearRangeWithStep(0, 4, 1),
 			},
 		},
 	}
@@ -524,16 +535,18 @@ func TestChartE2ELineWithFill(t *testing.T) {
 		Series: []Series{
 			ContinuousSeries{
 				Style: Style{
-					Show:        true,
 					StrokeColor: drawing.ColorBlue,
 					FillColor:   drawing.ColorRed,
 				},
-				XValues: seq.RangeWithStep(0, 4, 1),
+				XValues: LinearRangeWithStep(0, 4, 1),
-				YValues: seq.RangeWithStep(0, 4, 1),
+				YValues: LinearRangeWithStep(0, 4, 1),
 			},
 		},
 	}
 
+	assert.Equal(5, len(c.Series[0].(ContinuousSeries).XValues))
+	assert.Equal(5, len(c.Series[0].(ContinuousSeries).YValues))
+
 	var buffer = &bytes.Buffer{}
 	err := c.Render(PNG, buffer)
 	assert.Nil(err)

cmd/chart/main.go

@@ -3,118 +3,78 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"os"
-	"time"
+	"strings"
 
 	chart "github.com/wcharczuk/go-chart"
 )
 
 var (
 	outputPath        = flag.String("output", "", "The output file")
+	inputFormat       = flag.String("format", "csv", "The input format, either 'csv' or 'tsv' (defaults to 'csv')")
+	inputPath         = flag.String("f", "", "The input file")
 	disableLinreg     = flag.Bool("disable-linreg", false, "If we should omit linear regressions")
 	disableLastValues = flag.Bool("disable-last-values", false, "If we should omit last values")
 )
 
-// NewLogger returns a new logger.
+func main() {
-func NewLogger() *Logger {
+	flag.Parse()
-	return &Logger{
+	log := chart.NewLogger()
-		TimeFormat: time.RFC3339Nano,
-		Stdout:     os.Stdout,
-		Stderr:     os.Stderr,
-	}
-}
 
-// Logger is a basic logger.
+	var rawData []byte
-type Logger struct {
+	var err error
-	TimeFormat string
+	if *inputPath != "" {
-	Stdout     io.Writer
+		if *inputPath == "-" {
-	Stderr     io.Writer
+			rawData, err = ioutil.ReadAll(os.Stdin)
-}
-
-// Info writes an info message.
-func (l *Logger) Info(arguments ...interface{}) {
-	l.Println(append([]interface{}{"[INFO]"}, arguments...)...)
-}
-
-// Infof writes an info message.
-func (l *Logger) Infof(format string, arguments ...interface{}) {
-	l.Println(append([]interface{}{"[INFO]"}, fmt.Sprintf(format, arguments...))...)
-}
-
-// Debug writes an debug message.
-func (l *Logger) Debug(arguments ...interface{}) {
-	l.Println(append([]interface{}{"[DEBUG]"}, arguments...)...)
-}
-
-// Debugf writes an debug message.
-func (l *Logger) Debugf(format string, arguments ...interface{}) {
-	l.Println(append([]interface{}{"[DEBUG]"}, fmt.Sprintf(format, arguments...))...)
-}
-
-// Error writes an error message.
-func (l *Logger) Error(arguments ...interface{}) {
-	l.Println(append([]interface{}{"[ERROR]"}, arguments...)...)
-}
-
-// Errorf writes an error message.
-func (l *Logger) Errorf(format string, arguments ...interface{}) {
-	l.Println(append([]interface{}{"[ERROR]"}, fmt.Sprintf(format, arguments...))...)
-}
-
-// Err writes an error message.
-func (l *Logger) Err(err error) {
 			if err != nil {
-		l.Println(append([]interface{}{"[ERROR]"}, err.Error())...)
+				log.FatalErr(err)
 			}
-}
+		} else {
-
+			rawData, err = ioutil.ReadFile(*inputPath)
-// FatalErr writes an error message and exits.
-func (l *Logger) FatalErr(err error) {
 			if err != nil {
-		l.Println(append([]interface{}{"[FATAL]"}, err.Error())...)
+				log.FatalErr(err)
+			}
+		}
+	} else if len(flag.Args()) > 0 {
+		rawData = []byte(flag.Args()[0])
+	} else {
+		flag.Usage()
 		os.Exit(1)
 	}
+
+	var parts []string
+	switch *inputFormat {
+	case "csv":
+		parts = chart.SplitCSV(string(rawData))
+	case "tsv":
+		parts = strings.Split(string(rawData), "\t")
+	default:
+		log.FatalErr(fmt.Errorf("invalid format; must be 'csv' or 'tsv'"))
 	}
 
-// Println prints a new message.
+	yvalues, err := chart.ParseFloats(parts...)
-func (l *Logger) Println(arguments ...interface{}) {
-	fmt.Fprintln(l.Stdout, append([]interface{}{time.Now().UTC().Format(l.TimeFormat)}, arguments...)...)
-}
-
-// Errorln prints a new message.
-func (l *Logger) Errorln(arguments ...interface{}) {
-	fmt.Fprintln(l.Stderr, append([]interface{}{time.Now().UTC().Format(l.TimeFormat)}, arguments...)...)
-}
-
-func main() {
-	log := NewLogger()
-
-	rawData, err := ioutil.ReadAll(os.Stdin)
 	if err != nil {
 		log.FatalErr(err)
 	}
 
-	csvParts := chart.SplitCSV(string(rawData))
+	var series []chart.Series
-
-	yvalues, err := chart.ParseFloats(csvParts...)
-
 	mainSeries := chart.ContinuousSeries{
-		Name:    "A test series",
+		Name:    "Values",
-		XValues: chart.SeqRange(0, float64(len(csvParts))), //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
+		XValues: chart.LinearRange(1, float64(len(yvalues))),
 		YValues: yvalues,
 	}
+	series = append(series, mainSeries)
 
+	if !*disableLinreg {
 		linRegSeries := &chart.LinearRegressionSeries{
 			InnerSeries: mainSeries,
 		}
+		series = append(series, linRegSeries)
+	}
 
 	graph := chart.Chart{
-		Series: []chart.Series{
+		Series: series,
-			mainSeries,
-			linRegSeries,
-		},
 	}
 
 	var output *os.File
@@ -130,8 +90,10 @@ func main() {
 		}
 	}
 
-	log.Info("rendering chart to", output.Name())
 	if err := graph.Render(chart.PNG, output); err != nil {
 		log.FatalErr(err)
 	}
+
+	fmt.Fprintln(os.Stdout, output.Name())
+	os.Exit(0)
 }

concat_series_test.go

@@ -10,18 +10,18 @@ func TestConcatSeries(t *testing.T) {
 	assert := assert.New(t)
 
 	s1 := ContinuousSeries{
-		XValues: SeqRange(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
-		YValues: SeqRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
 	s2 := ContinuousSeries{
-		XValues: SeqRange(11, 20.0),
+		XValues: LinearRange(11, 20.0),
-		YValues: SeqRange(10.0, 1.0),
+		YValues: LinearRange(10.0, 1.0),
 	}
 
 	s3 := ContinuousSeries{
-		XValues: SeqRange(21, 30.0),
+		XValues: LinearRange(21, 30.0),
-		YValues: SeqRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
 	cs := ConcatSeries([]Series{s1, s2, s3})

continuous_range.go

@@ -62,6 +62,9 @@ func (r *ContinuousRange) SetDomain(domain int) {
 
 // String returns a simple string for the ContinuousRange.
 func (r ContinuousRange) String() string {
+	if r.GetDelta() == 0 {
+		return "ContinuousRange [empty]"
+	}
 	return fmt.Sprintf("ContinuousRange [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
 }
 

continuous_series.go

@@ -82,11 +82,15 @@ func (cs ContinuousSeries) Render(r Renderer, canvasBox Box, xrange, yrange Rang
 // Validate validates the series.
 func (cs ContinuousSeries) Validate() error {
 	if len(cs.XValues) == 0 {
-		return fmt.Errorf("continuous series must have xvalues set")
+		return fmt.Errorf("continuous series; must have xvalues set")
 	}
 
 	if len(cs.YValues) == 0 {
-		return fmt.Errorf("continuous series must have yvalues set")
+		return fmt.Errorf("continuous series; must have yvalues set")
+	}
+
+	if len(cs.XValues) != len(cs.YValues) {
+		return fmt.Errorf("continuous series; must have same length xvalues as yvalues")
 	}
 	return nil
 }

continuous_series_test.go

@@ -12,8 +12,8 @@ func TestContinuousSeries(t *testing.T) {
 
 	cs := ContinuousSeries{
 		Name:    "Test Series",
-		XValues: SeqRange(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
-		YValues: SeqRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
 	assert.Equal("Test Series", cs.GetName())
@@ -53,20 +53,20 @@ func TestContinuousSeriesValidate(t *testing.T) {
 
 	cs := ContinuousSeries{
 		Name:    "Test Series",
-		XValues: SeqRange(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
-		YValues: SeqRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 	assert.Nil(cs.Validate())
 
 	cs = ContinuousSeries{
 		Name:    "Test Series",
-		XValues: SeqRange(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
 	}
 	assert.NotNil(cs.Validate())
 
 	cs = ContinuousSeries{
 		Name:    "Test Series",
-		YValues: SeqRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 	assert.NotNil(cs.Validate())
 }

ema_series_test.go

@@ -4,11 +4,10 @@ import (
 	"testing"
 
 	"github.com/blend/go-sdk/assert"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 var (
-	emaXValues = seq.Range(1.0, 50.0)
+	emaXValues = LinearRange(1.0, 50.0)
 	emaYValues = []float64{
 		1, 2, 3, 4, 5, 4, 3, 2,
 		1, 2, 3, 4, 5, 4, 3, 2,

histogram_series_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 
 	assert "github.com/blend/go-sdk/assert"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 func TestHistogramSeries(t *testing.T) {
@@ -12,8 +11,8 @@ func TestHistogramSeries(t *testing.T) {
 
 	cs := ContinuousSeries{
 		Name:    "Test Series",
-		XValues: seq.Range(1.0, 20.0),
+		XValues: LinearRange(1.0, 20.0),
-		YValues: seq.Range(10.0, -10.0),
+		YValues: LinearRange(10.0, -10.0),
 	}
 
 	hs := HistogramSeries{

legend.go

@@ -35,7 +35,7 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
 		var labels []string
 		var lines []Style
 		for index, s := range c.Series {
-			if s.GetStyle().IsZero() || s.GetStyle().Show {
+			if !s.GetStyle().Hidden {
 				if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
 					labels = append(labels, s.GetName())
 					lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))
@@ -149,7 +149,7 @@ func LegendThin(c *Chart, userDefaults ...Style) Renderable {
 		var labels []string
 		var lines []Style
 		for index, s := range c.Series {
-			if s.GetStyle().IsZero() || s.GetStyle().Show {
+			if !s.GetStyle().Hidden {
 				if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
 					labels = append(labels, s.GetName())
 					lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))
@@ -247,7 +247,7 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
 		var labels []string
 		var lines []Style
 		for index, s := range c.Series {
-			if s.GetStyle().IsZero() || s.GetStyle().Show {
+			if !s.GetStyle().Hidden {
 				if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
 					labels = append(labels, s.GetName())
 					lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))

linear_regression_series_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 
 	assert "github.com/blend/go-sdk/assert"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 func TestLinearRegressionSeries(t *testing.T) {
@@ -12,8 +11,8 @@ func TestLinearRegressionSeries(t *testing.T) {
 
 	mainSeries := ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(1.0, 100.0),
+		XValues: LinearRange(1.0, 100.0),
-		YValues: seq.Range(1.0, 100.0),
+		YValues: LinearRange(1.0, 100.0),
 	}
 
 	linRegSeries := &LinearRegressionSeries{
@@ -34,8 +33,8 @@ func TestLinearRegressionSeriesDesc(t *testing.T) {
 
 	mainSeries := ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(100.0, 1.0),
+		XValues: LinearRange(100.0, 1.0),
-		YValues: seq.Range(100.0, 1.0),
+		YValues: LinearRange(100.0, 1.0),
 	}
 
 	linRegSeries := &LinearRegressionSeries{
@@ -56,8 +55,8 @@ func TestLinearRegressionSeriesWindowAndOffset(t *testing.T) {
 
 	mainSeries := ContinuousSeries{
 		Name:    "A test series",
-		XValues: seq.Range(100.0, 1.0),
+		XValues: LinearRange(100.0, 1.0),
-		YValues: seq.Range(100.0, 1.0),
+		YValues: LinearRange(100.0, 1.0),
 	}
 
 	linRegSeries := &LinearRegressionSeries{

linear_sequence.go

@@ -0,0 +1,73 @@
+package chart
+
+// LinearRange returns an array of values representing the range from start to end, incremented by 1.0.
+func LinearRange(start, end float64) []float64 {
+	return Seq{NewLinearSequence().WithStart(start).WithEnd(end).WithStep(1.0)}.Values()
+}
+
+// LinearRangeWithStep returns the array values of a linear seq with a given start, end and optional step.
+func LinearRangeWithStep(start, end, step float64) []float64 {
+	return Seq{NewLinearSequence().WithStart(start).WithEnd(end).WithStep(step)}.Values()
+}
+
+// NewLinearSequence returns a new linear generator.
+func NewLinearSequence() *LinearSeq {
+	return &LinearSeq{step: 1.0}
+}
+
+// LinearSeq is a stepwise generator.
+type LinearSeq struct {
+	start float64
+	end   float64
+	step  float64
+}
+
+// Start returns the start value.
+func (lg LinearSeq) Start() float64 {
+	return lg.start
+}
+
+// End returns the end value.
+func (lg LinearSeq) End() float64 {
+	return lg.end
+}
+
+// Step returns the step value.
+func (lg LinearSeq) Step() float64 {
+	return lg.step
+}
+
+// Len returns the number of elements in the seq.
+func (lg LinearSeq) Len() int {
+	if lg.start < lg.end {
+		return int((lg.end-lg.start)/lg.step) + 1
+	}
+	return int((lg.start-lg.end)/lg.step) + 1
+}
+
+// GetValue returns the value at a given index.
+func (lg LinearSeq) GetValue(index int) float64 {
+	fi := float64(index)
+	if lg.start < lg.end {
+		return lg.start + (fi * lg.step)
+	}
+	return lg.start - (fi * lg.step)
+}
+
+// WithStart sets the start and returns the linear generator.
+func (lg *LinearSeq) WithStart(start float64) *LinearSeq {
+	lg.start = start
+	return lg
+}
+
+// WithEnd sets the end and returns the linear generator.
+func (lg *LinearSeq) WithEnd(end float64) *LinearSeq {
+	lg.end = end
+	return lg
+}
+
+// WithStep sets the step and returns the linear generator.
+func (lg *LinearSeq) WithStep(step float64) *LinearSeq {
+	lg.step = step
+	return lg
+}

logger.go

@@ -0,0 +1,129 @@
+package chart
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"time"
+)
+
+var (
+	_ Logger = (*StdoutLogger)(nil)
+)
+
+// NewLogger returns a new logger.
+func NewLogger() Logger {
+	return &StdoutLogger{
+		TimeFormat: time.RFC3339Nano,
+		Stdout:     os.Stdout,
+		Stderr:     os.Stderr,
+	}
+}
+
+// Logger is a type that implements the logging interface.
+type Logger interface {
+	Info(...interface{})
+	Infof(string, ...interface{})
+	Debug(...interface{})
+	Debugf(string, ...interface{})
+	Err(error)
+	FatalErr(error)
+	Error(...interface{})
+	Errorf(string, ...interface{})
+	Println(...interface{})
+	Errorln(...interface{})
+}
+
+// Info logs an info message if the logger is set.
+func Info(log Logger, arguments ...interface{}) {
+	if log == nil {
+		return
+	}
+	log.Info(arguments...)
+}
+
+// Infof logs an info message if the logger is set.
+func Infof(log Logger, format string, arguments ...interface{}) {
+	if log == nil {
+		return
+	}
+	log.Infof(format, arguments...)
+}
+
+// Debug logs an debug message if the logger is set.
+func Debug(log Logger, arguments ...interface{}) {
+	if log == nil {
+		return
+	}
+	log.Debug(arguments...)
+}
+
+// Debugf logs an debug message if the logger is set.
+func Debugf(log Logger, format string, arguments ...interface{}) {
+	if log == nil {
+		return
+	}
+	log.Debugf(format, arguments...)
+}
+
+// StdoutLogger is a basic logger.
+type StdoutLogger struct {
+	TimeFormat string
+	Stdout     io.Writer
+	Stderr     io.Writer
+}
+
+// Info writes an info message.
+func (l *StdoutLogger) Info(arguments ...interface{}) {
+	l.Println(append([]interface{}{"[INFO]"}, arguments...)...)
+}
+
+// Infof writes an info message.
+func (l *StdoutLogger) Infof(format string, arguments ...interface{}) {
+	l.Println(append([]interface{}{"[INFO]"}, fmt.Sprintf(format, arguments...))...)
+}
+
+// Debug writes an debug message.
+func (l *StdoutLogger) Debug(arguments ...interface{}) {
+	l.Println(append([]interface{}{"[DEBUG]"}, arguments...)...)
+}
+
+// Debugf writes an debug message.
+func (l *StdoutLogger) Debugf(format string, arguments ...interface{}) {
+	l.Println(append([]interface{}{"[DEBUG]"}, fmt.Sprintf(format, arguments...))...)
+}
+
+// Error writes an error message.
+func (l *StdoutLogger) Error(arguments ...interface{}) {
+	l.Println(append([]interface{}{"[ERROR]"}, arguments...)...)
+}
+
+// Errorf writes an error message.
+func (l *StdoutLogger) Errorf(format string, arguments ...interface{}) {
+	l.Println(append([]interface{}{"[ERROR]"}, fmt.Sprintf(format, arguments...))...)
+}
+
+// Err writes an error message.
+func (l *StdoutLogger) Err(err error) {
+	if err != nil {
+		l.Println(append([]interface{}{"[ERROR]"}, err.Error())...)
+	}
+}
+
+// FatalErr writes an error message and exits.
+func (l *StdoutLogger) FatalErr(err error) {
+	if err != nil {
+		l.Println(append([]interface{}{"[FATAL]"}, err.Error())...)
+		os.Exit(1)
+	}
+}
+
+// Println prints a new message.
+func (l *StdoutLogger) Println(arguments ...interface{}) {
+	fmt.Fprintln(l.Stdout, append([]interface{}{time.Now().UTC().Format(l.TimeFormat)}, arguments...)...)
+}
+
+// Errorln prints a new message.
+func (l *StdoutLogger) Errorln(arguments ...interface{}) {
+	fmt.Fprintln(l.Stderr, append([]interface{}{time.Now().UTC().Format(l.TimeFormat)}, arguments...)...)
+}

parse.go

@@ -2,6 +2,7 @@ package chart
 
 import (
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/blend/go-sdk/exception"
@@ -12,8 +13,13 @@ func ParseFloats(values ...string) ([]float64, error) {
 	var output []float64
 	var parsedValue float64
 	var err error
+	var cleaned string
 	for _, value := range values {
-		if parsedValue, err = strconv.ParseFloat(value, 64); err != nil {
+		cleaned = strings.TrimSpace(strings.Replace(value, ",", "", -1))
+		if cleaned == "" {
+			continue
+		}
+		if parsedValue, err = strconv.ParseFloat(cleaned, 64); err != nil {
 			return nil, exception.New(err)
 		}
 		output = append(output, parsedValue)

pie_chart.go

@@ -116,7 +116,7 @@ func (pc PieChart) drawCanvas(r Renderer, canvasBox Box) {
 }
 
 func (pc PieChart) drawTitle(r Renderer) {
-	if len(pc.Title) > 0 && pc.TitleStyle.Show {
+	if len(pc.Title) > 0 && !pc.TitleStyle.Hidden {
 		Draw.TextWithin(r, pc.Title, pc.Box(), pc.styleDefaultsTitle())
 	}
 }

random_sequence.go

@@ -0,0 +1,92 @@
+package chart
+
+import (
+	"math"
+	"math/rand"
+	"time"
+)
+
+var (
+	_ Sequence = (*RandomSeq)(nil)
+)
+
+// RandomValues returns an array of random values.
+func RandomValues(count int) []float64 {
+	return Seq{NewRandomSequence().WithLen(count)}.Values()
+}
+
+// RandomValuesWithMax returns an array of random values with a given average.
+func RandomValuesWithMax(count int, max float64) []float64 {
+	return Seq{NewRandomSequence().WithMax(max).WithLen(count)}.Values()
+}
+
+// NewRandomSequence creates a new random seq.
+func NewRandomSequence() *RandomSeq {
+	return &RandomSeq{
+		rnd: rand.New(rand.NewSource(time.Now().Unix())),
+	}
+}
+
+// RandomSeq is a random number seq generator.
+type RandomSeq struct {
+	rnd *rand.Rand
+	max *float64
+	min *float64
+	len *int
+}
+
+// Len returns the number of elements that will be generated.
+func (r *RandomSeq) Len() int {
+	if r.len != nil {
+		return *r.len
+	}
+	return math.MaxInt32
+}
+
+// GetValue returns the value.
+func (r *RandomSeq) GetValue(_ int) float64 {
+	if r.min != nil && r.max != nil {
+		var delta float64
+
+		if *r.max > *r.min {
+			delta = *r.max - *r.min
+		} else {
+			delta = *r.min - *r.max
+		}
+
+		return *r.min + (r.rnd.Float64() * delta)
+	} else if r.max != nil {
+		return r.rnd.Float64() * *r.max
+	} else if r.min != nil {
+		return *r.min + (r.rnd.Float64())
+	}
+	return r.rnd.Float64()
+}
+
+// WithLen sets a maximum len
+func (r *RandomSeq) WithLen(length int) *RandomSeq {
+	r.len = &length
+	return r
+}
+
+// Min returns the minimum value.
+func (r RandomSeq) Min() *float64 {
+	return r.min
+}
+
+// WithMin sets the scale and returns the Random.
+func (r *RandomSeq) WithMin(min float64) *RandomSeq {
+	r.min = &min
+	return r
+}
+
+// Max returns the maximum value.
+func (r RandomSeq) Max() *float64 {
+	return r.max
+}
+
+// WithMax sets the average and returns the Random.
+func (r *RandomSeq) WithMax(max float64) *RandomSeq {
+	r.max = &max
+	return r
+}

seq.go

@@ -3,19 +3,22 @@ package chart
 import (
 	"math"
 	"sort"
-	"time"
-
-	"github.com/blend/go-sdk/timeutil"
 )
 
-// NewSeq wraps a provider with a seq.
+// ValueSequence returns a sequence for a given values set.
-func NewSeq(provider SeqProvider) Seq {
+func ValueSequence(values ...float64) Seq {
-	return Seq{SeqProvider: provider}
+	return Seq{NewArray(values...)}
+}
+
+// Sequence is a provider for values for a seq.
+type Sequence interface {
+	Len() int
+	GetValue(int) float64
 }
 
 // Seq is a utility wrapper for seq providers.
 type Seq struct {
-	SeqProvider
+	Sequence
 }
 
 // Values enumerates the seq into a slice.
@@ -45,7 +48,7 @@ func (s Seq) Map(mapfn func(i int, v float64) float64) Seq {
 	for i := 0; i < s.Len(); i++ {
 		mapfn(i, s.GetValue(i))
 	}
-	return Seq{SeqArray(output)}
+	return Seq{Array(output)}
 }
 
 // FoldLeft collapses a seq from left to right.
@@ -142,7 +145,7 @@ func (s Seq) Sort() Seq {
 	}
 	values := s.Values()
 	sort.Float64s(values)
-	return Seq{SeqArray(values)}
+	return Seq{Array(values)}
 }
 
 // Median returns the median or middle value in the sorted seq.
@@ -247,160 +250,5 @@ func (s Seq) Normalize() Seq {
 		output[i] = (s.GetValue(i) - min) / delta
 	}
 
-	return Seq{SeqProvider: SeqArray(output)}
+	return Seq{Array(output)}
-}
-
-// SeqProvider is a provider for values for a seq.
-type SeqProvider interface {
-	Len() int
-	GetValue(int) float64
-}
-
-// SeqArray is a wrapper for an array of floats that implements `ValuesProvider`.
-type SeqArray []float64
-
-// Len returns the value provider length.
-func (a SeqArray) Len() int {
-	return len(a)
-}
-
-// GetValue returns the value at a given index.
-func (a SeqArray) GetValue(index int) float64 {
-	return a[index]
-}
-
-// SeqDays generates a seq of timestamps by day, from -days to today.
-func SeqDays(days int) []time.Time {
-	var values []time.Time
-	for day := days; day >= 0; day-- {
-		values = append(values, time.Now().AddDate(0, 0, -day))
-	}
-	return values
-}
-
-// SeqHours returns a sequence of times by the hour for a given number of hours
-// after a given start.
-func SeqHours(start time.Time, totalHours int) []time.Time {
-	times := make([]time.Time, totalHours)
-
-	last := start
-	for i := 0; i < totalHours; i++ {
-		times[i] = last
-		last = last.Add(time.Hour)
-	}
-
-	return times
-}
-
-// SeqHoursFilled adds zero values for the data bounded by the start and end of the xdata array.
-func SeqHoursFilled(xdata []time.Time, ydata []float64) ([]time.Time, []float64) {
-	start, end := TimeMinMax(xdata...)
-	totalHours := DiffHours(start, end)
-
-	finalTimes := SeqHours(start, totalHours+1)
-	finalValues := make([]float64, totalHours+1)
-
-	var hoursFromStart int
-	for i, xd := range xdata {
-		hoursFromStart = DiffHours(start, xd)
-		finalValues[hoursFromStart] = ydata[i]
-	}
-
-	return finalTimes, finalValues
-}
-
-// Assert types implement interfaces.
-var (
-	_ SeqProvider = (*SeqTimes)(nil)
-)
-
-// SeqTimes are an array of times.
-// It wraps the array with methods that implement `seq.Provider`.
-type SeqTimes []time.Time
-
-// Array returns the times to an array.
-func (t SeqTimes) Array() []time.Time {
-	return []time.Time(t)
-}
-
-// Len returns the length of the array.
-func (t SeqTimes) Len() int {
-	return len(t)
-}
-
-// GetValue returns a value at an index as a time.
-func (t SeqTimes) GetValue(index int) float64 {
-	return timeutil.ToFloat64(t[index])
-}
-
-// SeqRange returns the array values of a linear seq with a given start, end and optional step.
-func SeqRange(start, end float64) []float64 {
-	return Seq{NewSeqLinear().WithStart(start).WithEnd(end).WithStep(1.0)}.Values()
-}
-
-// SeqRangeWithStep returns the array values of a linear seq with a given start, end and optional step.
-func SeqRangeWithStep(start, end, step float64) []float64 {
-	return Seq{NewSeqLinear().WithStart(start).WithEnd(end).WithStep(step)}.Values()
-}
-
-// NewSeqLinear returns a new linear generator.
-func NewSeqLinear() *SeqLinear {
-	return &SeqLinear{step: 1.0}
-}
-
-// SeqLinear is a stepwise generator.
-type SeqLinear struct {
-	start float64
-	end   float64
-	step  float64
-}
-
-// Start returns the start value.
-func (lg SeqLinear) Start() float64 {
-	return lg.start
-}
-
-// End returns the end value.
-func (lg SeqLinear) End() float64 {
-	return lg.end
-}
-
-// Step returns the step value.
-func (lg SeqLinear) Step() float64 {
-	return lg.step
-}
-
-// Len returns the number of elements in the seq.
-func (lg SeqLinear) Len() int {
-	if lg.start < lg.end {
-		return int((lg.end-lg.start)/lg.step) + 1
-	}
-	return int((lg.start-lg.end)/lg.step) + 1
-}
-
-// GetValue returns the value at a given index.
-func (lg SeqLinear) GetValue(index int) float64 {
-	fi := float64(index)
-	if lg.start < lg.end {
-		return lg.start + (fi * lg.step)
-	}
-	return lg.start - (fi * lg.step)
-}
-
-// WithStart sets the start and returns the linear generator.
-func (lg *SeqLinear) WithStart(start float64) *SeqLinear {
-	lg.start = start
-	return lg
-}
-
-// WithEnd sets the end and returns the linear generator.
-func (lg *SeqLinear) WithEnd(end float64) *SeqLinear {
-	lg.end = end
-	return lg
-}
-
-// WithStep sets the step and returns the linear generator.
-func (lg *SeqLinear) WithStep(step float64) *SeqLinear {
-	lg.step = step
-	return lg
 }

seq_test.go

@@ -0,0 +1,136 @@
+package chart
+
+import (
+	"testing"
+
+	assert "github.com/blend/go-sdk/assert"
+)
+
+func TestSeqEach(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	values.Each(func(i int, v float64) {
+		assert.Equal(i, v-1)
+	})
+}
+
+func TestSeqMap(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	mapped := values.Map(func(i int, v float64) float64 {
+		assert.Equal(i, v-1)
+		return v * 2
+	})
+	assert.Equal(4, mapped.Len())
+}
+
+func TestSeqFoldLeft(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	ten := values.FoldLeft(func(_ int, vp, v float64) float64 {
+		return vp + v
+	})
+	assert.Equal(10, ten)
+
+	orderTest := Seq{NewArray(10, 3, 2, 1)}
+	four := orderTest.FoldLeft(func(_ int, vp, v float64) float64 {
+		return vp - v
+	})
+	assert.Equal(4, four)
+}
+
+func TestSeqFoldRight(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	ten := values.FoldRight(func(_ int, vp, v float64) float64 {
+		return vp + v
+	})
+	assert.Equal(10, ten)
+
+	orderTest := Seq{NewArray(10, 3, 2, 1)}
+	notFour := orderTest.FoldRight(func(_ int, vp, v float64) float64 {
+		return vp - v
+	})
+	assert.Equal(-14, notFour)
+}
+
+func TestSeqSum(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	assert.Equal(10, values.Sum())
+}
+
+func TestSeqAverage(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4)}
+	assert.Equal(2.5, values.Average())
+
+	valuesOdd := Seq{NewArray(1, 2, 3, 4, 5)}
+	assert.Equal(3, valuesOdd.Average())
+}
+
+func TestSequenceVariance(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{NewArray(1, 2, 3, 4, 5)}
+	assert.Equal(2, values.Variance())
+}
+
+func TestSequenceNormalize(t *testing.T) {
+	assert := assert.New(t)
+
+	normalized := ValueSequence(1, 2, 3, 4, 5).Normalize().Values()
+
+	assert.NotEmpty(normalized)
+	assert.Len(normalized, 5)
+	assert.Equal(0, normalized[0])
+	assert.Equal(0.25, normalized[1])
+	assert.Equal(1, normalized[4])
+}
+
+func TestLinearRange(t *testing.T) {
+	assert := assert.New(t)
+
+	values := LinearRange(1, 100)
+	assert.Len(values, 100)
+	assert.Equal(1, values[0])
+	assert.Equal(100, values[99])
+}
+
+func TestLinearRangeWithStep(t *testing.T) {
+	assert := assert.New(t)
+
+	values := LinearRangeWithStep(0, 100, 5)
+	assert.Equal(100, values[20])
+	assert.Len(values, 21)
+}
+
+func TestLinearRangeReversed(t *testing.T) {
+	assert := assert.New(t)
+
+	values := LinearRange(10.0, 1.0)
+	assert.Equal(10, len(values))
+	assert.Equal(10.0, values[0])
+	assert.Equal(1.0, values[9])
+}
+
+func TestLinearSequenceRegression(t *testing.T) {
+	assert := assert.New(t)
+
+	// note; this assumes a 1.0 step is implicitly set in the constructor.
+	linearProvider := NewLinearSequence().WithStart(1.0).WithEnd(100.0)
+	assert.Equal(1, linearProvider.Start())
+	assert.Equal(100, linearProvider.End())
+	assert.Equal(100, linearProvider.Len())
+
+	values := Seq{linearProvider}.Values()
+	assert.Len(values, 100)
+	assert.Equal(1.0, values[0])
+	assert.Equal(100, values[99])
+}

sma_series_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 
 	"github.com/blend/go-sdk/assert"
-	"github.com/wcharczuk/go-chart/seq"
 )
 
 type mockValuesProvider struct {
@@ -32,8 +31,8 @@ func TestSMASeriesGetValue(t *testing.T) {
 	assert := assert.New(t)
 
 	mockSeries := mockValuesProvider{
-		seq.Range(1.0, 10.0),
+		LinearRange(1.0, 10.0),
-		seq.Range(10, 1.0),
+		LinearRange(10, 1.0),
 	}
 	assert.Equal(10, mockSeries.Len())
 
@@ -63,8 +62,8 @@ func TestSMASeriesGetLastValueWindowOverlap(t *testing.T) {
 	assert := assert.New(t)
 
 	mockSeries := mockValuesProvider{
-		seq.Range(1.0, 10.0),
+		LinearRange(1.0, 10.0),
-		seq.Range(10, 1.0),
+		LinearRange(10, 1.0),
 	}
 	assert.Equal(10, mockSeries.Len())
 
@@ -89,8 +88,8 @@ func TestSMASeriesGetLastValue(t *testing.T) {
 	assert := assert.New(t)
 
 	mockSeries := mockValuesProvider{
-		seq.Range(1.0, 100.0),
+		LinearRange(1.0, 100.0),
-		seq.Range(100, 1.0),
+		LinearRange(100, 1.0),
 	}
 	assert.Equal(100, mockSeries.Len())
 

stacked_bar_chart.go

@@ -162,7 +162,7 @@ func (sbc StackedBarChart) drawBar(r Renderer, canvasBox Box, xoffset int, bar S
 }
 
 func (sbc StackedBarChart) drawXAxis(r Renderer, canvasBox Box) {
-	if sbc.XAxis.Show {
+	if !sbc.XAxis.Hidden {
 		axisStyle := sbc.XAxis.InheritFrom(sbc.styleDefaultsAxes())
 		axisStyle.WriteToRenderer(r)
 
@@ -196,7 +196,7 @@ func (sbc StackedBarChart) drawXAxis(r Renderer, canvasBox Box) {
 }
 
 func (sbc StackedBarChart) drawYAxis(r Renderer, canvasBox Box) {
-	if sbc.YAxis.Show {
+	if !sbc.YAxis.Hidden {
 		axisStyle := sbc.YAxis.InheritFrom(sbc.styleDefaultsAxes())
 		axisStyle.WriteToRenderer(r)
 		r.MoveTo(canvasBox.Right, canvasBox.Top)
@@ -207,7 +207,7 @@ func (sbc StackedBarChart) drawYAxis(r Renderer, canvasBox Box) {
 		r.LineTo(canvasBox.Right+DefaultHorizontalTickWidth, canvasBox.Bottom)
 		r.Stroke()
 
-		ticks := SeqRangeWithStep(0.0, 1.0, 0.2)
+		ticks := LinearRangeWithStep(0.0, 1.0, 0.2)
 		for _, t := range ticks {
 			axisStyle.GetStrokeOptions().WriteToRenderer(r)
 			ty := canvasBox.Bottom - int(t*float64(canvasBox.Height()))
@@ -226,7 +226,7 @@ func (sbc StackedBarChart) drawYAxis(r Renderer, canvasBox Box) {
 }
 
 func (sbc StackedBarChart) drawTitle(r Renderer) {
-	if len(sbc.Title) > 0 && sbc.TitleStyle.Show {
+	if len(sbc.Title) > 0 && !sbc.TitleStyle.Hidden {
 		r.SetFont(sbc.TitleStyle.GetFont(sbc.GetFont()))
 		r.SetFontColor(sbc.TitleStyle.GetFontColor(sbc.GetColorPalette().TextColor()))
 		titleFontSize := sbc.TitleStyle.GetFontSize(DefaultTitleFontSize)
@@ -274,7 +274,7 @@ func (sbc StackedBarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box) Box {
 		totalWidth += bar.GetWidth() + sbc.GetBarSpacing()
 	}
 
-	if sbc.XAxis.Show {
+	if !sbc.XAxis.Hidden {
 		xaxisHeight := DefaultVerticalTickHeight
 
 		axisStyle := sbc.XAxis.InheritFrom(sbc.styleDefaultsAxes())

style.go

@@ -14,10 +14,18 @@ const (
 	Disabled = -1
 )
 
-// StyleShow is a prebuilt style with the `Show` property set to true.
+// Hidden is a prebuilt style with the `Hidden` property set to true.
-func StyleShow() Style {
+func Hidden() Style {
 	return Style{
-		Show: true,
+		Hidden: true,
+	}
+}
+
+// Shown is a prebuilt style with the `Hidden` property set to false.
+// You can also think of this as the default.
+func Shown() Style {
+	return Style{
+		Hidden: false,
 	}
 }
 
@@ -26,7 +34,7 @@ func StyleShow() Style {
 func StyleTextDefaults() Style {
 	font, _ := GetDefaultFont()
 	return Style{
-		Show:      true,
+		Hidden:    false,
 		Font:      font,
 		FontColor: DefaultTextColor,
 		FontSize:  DefaultTitleFontSize,
@@ -35,7 +43,7 @@ func StyleTextDefaults() Style {
 
 // Style is a simple style set.
 type Style struct {
-	Show    bool
+	Hidden  bool
 	Padding Box
 
 	ClassName string
@@ -65,7 +73,8 @@ type Style struct {
 
 // IsZero returns if the object is set or not.
 func (s Style) IsZero() bool {
-	return s.StrokeColor.IsZero() &&
+	return !s.Hidden &&
+		s.StrokeColor.IsZero() &&
 		s.StrokeWidth == 0 &&
 		s.DotColor.IsZero() &&
 		s.DotWidth == 0 &&
@@ -83,10 +92,10 @@ func (s Style) String() string {
 	}
 
 	var output []string
-	if s.Show {
+	if s.Hidden {
-		output = []string{"\"show\": true"}
+		output = []string{"\"hidden\": true"}
 	} else {
-		output = []string{"\"show\": false"}
+		output = []string{"\"hidden\": false"}
 	}
 
 	if s.ClassName != "" {

times.go

@@ -0,0 +1,43 @@
+package chart
+
+import (
+	"sort"
+	"time"
+
+	"github.com/blend/go-sdk/timeutil"
+)
+
+// Assert types implement interfaces.
+var (
+	_ Sequence       = (*Times)(nil)
+	_ sort.Interface = (*Times)(nil)
+)
+
+// Times are an array of times.
+// It wraps the array with methods that implement `seq.Provider`.
+type Times []time.Time
+
+// Array returns the times to an array.
+func (t Times) Array() []time.Time {
+	return []time.Time(t)
+}
+
+// Len returns the length of the array.
+func (t Times) Len() int {
+	return len(t)
+}
+
+// GetValue returns a value at an index as a time.
+func (t Times) GetValue(index int) float64 {
+	return timeutil.ToFloat64(t[index])
+}
+
+// Swap implements sort.Interface.
+func (t Times) Swap(i, j int) {
+	t[i], t[j] = t[j], t[i]
+}
+
+// Less implements sort.Interface.
+func (t Times) Less(i, j int) bool {
+	return t[i].Before(t[j])
+}

timeutil.go

@@ -80,6 +80,11 @@ func TimeToFloat64(t time.Time) float64 {
 	return float64(t.UnixNano())
 }
 
+// TimeFromFloat64 returns a time from a float64.
+func TimeFromFloat64(tf float64) time.Time {
+	return time.Unix(0, int64(tf))
+}
+
 // TimeDescending sorts a given list of times ascending, or min to max.
 type TimeDescending []time.Time
 
@@ -103,3 +108,43 @@ func (a TimeAscending) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
 
 // Less implements sort.Sorter
 func (a TimeAscending) Less(i, j int) bool { return a[i].Before(a[j]) }
+
+// Days generates a seq of timestamps by day, from -days to today.
+func Days(days int) []time.Time {
+	var values []time.Time
+	for day := days; day >= 0; day-- {
+		values = append(values, time.Now().AddDate(0, 0, -day))
+	}
+	return values
+}
+
+// Hours returns a sequence of times by the hour for a given number of hours
+// after a given start.
+func Hours(start time.Time, totalHours int) []time.Time {
+	times := make([]time.Time, totalHours)
+
+	last := start
+	for i := 0; i < totalHours; i++ {
+		times[i] = last
+		last = last.Add(time.Hour)
+	}
+
+	return times
+}
+
+// HoursFilled adds zero values for the data bounded by the start and end of the xdata array.
+func HoursFilled(xdata []time.Time, ydata []float64) ([]time.Time, []float64) {
+	start, end := TimeMinMax(xdata...)
+	totalHours := DiffHours(start, end)
+
+	finalTimes := Hours(start, totalHours+1)
+	finalValues := make([]float64, totalHours+1)
+
+	var hoursFromStart int
+	for i, xd := range xdata {
+		hoursFromStart = DiffHours(start, xd)
+		finalValues[hoursFromStart] = ydata[i]
+	}
+
+	return finalTimes, finalValues
+}

value_buffer.go

@@ -149,7 +149,7 @@ func (b *ValueBuffer) TrimExcess() {
 }
 
 // Array returns the ring buffer, in order, as an array.
-func (b *ValueBuffer) Array() SeqArray {
+func (b *ValueBuffer) Array() Array {
 	newArray := make([]float64, b.size)
 
 	if b.size == 0 {
@@ -163,7 +163,7 @@ func (b *ValueBuffer) Array() SeqArray {
 		arrayCopy(b.array, 0, newArray, len(b.array)-b.head, b.tail)
 	}
 
-	return SeqArray(newArray)
+	return Array(newArray)
 }
 
 // Each calls the consumer for each element in the buffer.

value_buffer_test.go

@@ -6,10 +6,10 @@ import (
 	"github.com/blend/go-sdk/assert"
 )
 
-func TestRingBuffer(t *testing.T) {
+func TestBuffer(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	buffer := NewValueBuffer()
 
 	buffer.Enqueue(1)
 	assert.Equal(1, buffer.Len())
@@ -96,14 +96,14 @@ func TestRingBuffer(t *testing.T) {
 	value = buffer.Dequeue()
 	assert.Equal(8, value)
 	assert.Equal(0, buffer.Len())
-	assert.Nil(buffer.Peek())
+	assert.Zero(buffer.Peek())
-	assert.Nil(buffer.PeekBack())
+	assert.Zero(buffer.PeekBack())
 }
 
-func TestRingBufferClear(t *testing.T) {
+func TestBufferClear(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	buffer := NewValueBuffer()
 	buffer.Enqueue(1)
 	buffer.Enqueue(1)
 	buffer.Enqueue(1)
@@ -117,21 +117,21 @@ func TestRingBufferClear(t *testing.T) {
 
 	buffer.Clear()
 	assert.Equal(0, buffer.Len())
-	assert.Nil(buffer.Peek())
+	assert.Zero(buffer.Peek())
-	assert.Nil(buffer.PeekBack())
+	assert.Zero(buffer.PeekBack())
 }
 
-func TestRingBufferContents(t *testing.T) {
+func TestBufferArray(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	buffer := NewValueBuffer()
 	buffer.Enqueue(1)
 	buffer.Enqueue(2)
 	buffer.Enqueue(3)
 	buffer.Enqueue(4)
 	buffer.Enqueue(5)
 
-	contents := buffer.Contents()
+	contents := buffer.Array()
 	assert.Len(contents, 5)
 	assert.Equal(1, contents[0])
 	assert.Equal(2, contents[1])
@@ -140,145 +140,53 @@ func TestRingBufferContents(t *testing.T) {
 	assert.Equal(5, contents[4])
 }
 
-func TestRingBufferDrain(t *testing.T) {
+func TestBufferEach(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	buffer := NewValueBuffer()
-	buffer.Enqueue(1)
-	buffer.Enqueue(2)
-	buffer.Enqueue(3)
-	buffer.Enqueue(4)
-	buffer.Enqueue(5)
-
-	contents := buffer.Drain()
-	assert.Len(contents, 5)
-	assert.Equal(1, contents[0])
-	assert.Equal(2, contents[1])
-	assert.Equal(3, contents[2])
-	assert.Equal(4, contents[3])
-	assert.Equal(5, contents[4])
-
-	assert.Equal(0, buffer.Len())
-	assert.Nil(buffer.Peek())
-	assert.Nil(buffer.PeekBack())
-}
-
-func TestRingBufferEach(t *testing.T) {
-	assert := assert.New(t)
-
-	buffer := NewRingBuffer()
 
 	for x := 1; x < 17; x++ {
-		buffer.Enqueue(x)
+		buffer.Enqueue(float64(x))
 	}
 
 	called := 0
-	buffer.Each(func(v interface{}) {
+	buffer.Each(func(_ int, v float64) {
-		if typed, isTyped := v.(int); isTyped {
+		if v == float64(called+1) {
-			if typed == (called + 1) {
 			called++
 		}
-		}
 	})
 
 	assert.Equal(16, called)
 }
 
-func TestRingBufferEachUntil(t *testing.T) {
+func TestNewBuffer(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	empty := NewValueBuffer()
-
+	assert.NotNil(empty)
-	for x := 1; x < 17; x++ {
+	assert.Zero(empty.Len())
-		buffer.Enqueue(x)
+	assert.Equal(bufferDefaultCapacity, empty.Capacity())
+	assert.Zero(empty.Peek())
+	assert.Zero(empty.PeekBack())
 }
 
-	called := 0
+func TestNewBufferWithValues(t *testing.T) {
-	buffer.EachUntil(func(v interface{}) bool {
-		if typed, isTyped := v.(int); isTyped {
-			if typed > 10 {
-				return false
-			}
-			if typed == (called + 1) {
-				called++
-			}
-		}
-		return true
-	})
-
-	assert.Equal(10, called)
-}
-
-func TestRingBufferReverseEachUntil(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBufferWithCapacity(32)
+	values := NewValueBuffer(1, 2, 3, 4, 5)
-
+	assert.NotNil(values)
-	for x := 1; x < 17; x++ {
+	assert.Equal(5, values.Len())
-		buffer.Enqueue(x)
+	assert.Equal(1, values.Peek())
+	assert.Equal(5, values.PeekBack())
 }
 
-	var values []int
+func TestBufferGrowth(t *testing.T) {
-	buffer.ReverseEachUntil(func(v interface{}) bool {
-		if typed, isTyped := v.(int); isTyped {
-			if typed < 10 {
-				return false
-			}
-			values = append(values, typed)
-			return true
-		}
-		panic("value is not an integer")
-	})
-
-	assert.Len(values, 7)
-	assert.Equal(16, values[0])
-	assert.Equal(10, values[6])
-}
-
-func TestRingBufferReverseEachUntilUndersized(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewRingBuffer()
+	values := NewValueBuffer(1, 2, 3, 4, 5)
-
+	for i := 0; i < 1<<10; i++ {
-	for x := 1; x < 17; x++ {
+		values.Enqueue(float64(i))
-		buffer.Enqueue(x)
 	}
 
-	var values []int
+	assert.Equal(1<<10-1, values.PeekBack())
-	buffer.ReverseEachUntil(func(v interface{}) bool {
-		if typed, isTyped := v.(int); isTyped {
-			if typed < 10 {
-				return false
-			}
-			values = append(values, typed)
-			return true
-		}
-		panic("value is not an integer")
-	})
-
-	assert.Len(values, 7)
-	assert.Equal(16, values[0])
-	assert.Equal(10, values[6])
-}
-
-func TestRingBufferConsume(t *testing.T) {
-	assert := assert.New(t)
-
-	buffer := NewRingBuffer()
-
-	for x := 1; x < 17; x++ {
-		buffer.Enqueue(x)
-	}
-
-	assert.Equal(16, buffer.Len())
-
-	var called int
-	buffer.Consume(func(v interface{}) {
-		if _, isTyped := v.(int); isTyped {
-			called++
-		}
-	})
-
-	assert.Equal(16, called)
-	assert.Zero(buffer.Len())
 }

xaxis.go

@@ -108,7 +108,7 @@ func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, tic
 		bottom = MaxInt(bottom, ty)
 	}
 
-	if xa.NameStyle.Show && len(xa.Name) > 0 {
+	if !xa.NameStyle.Hidden && len(xa.Name) > 0 {
 		tb := Draw.MeasureText(r, xa.Name, xa.NameStyle.InheritFrom(defaults))
 		bottom += DefaultXAxisMargin + tb.Height()
 	}
@@ -180,16 +180,16 @@ func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, tick
 	}
 
 	nameStyle := xa.NameStyle.InheritFrom(defaults)
-	if xa.NameStyle.Show && len(xa.Name) > 0 {
+	if !xa.NameStyle.Hidden && len(xa.Name) > 0 {
 		tb := Draw.MeasureText(r, xa.Name, nameStyle)
 		tx := canvasBox.Right - (canvasBox.Width()>>1 + tb.Width()>>1)
 		ty := canvasBox.Bottom + DefaultXAxisMargin + maxTextHeight + DefaultXAxisMargin + tb.Height()
 		Draw.Text(r, xa.Name, tx, ty, nameStyle)
 	}
 
-	if xa.GridMajorStyle.Show || xa.GridMinorStyle.Show {
+	if !xa.GridMajorStyle.Hidden || !xa.GridMinorStyle.Hidden {
 		for _, gl := range xa.GetGridLines(ticks) {
-			if (gl.IsMinor && xa.GridMinorStyle.Show) || (!gl.IsMinor && xa.GridMajorStyle.Show) {
+			if (gl.IsMinor && !xa.GridMinorStyle.Hidden) || (!gl.IsMinor && !xa.GridMajorStyle.Hidden) {
 				defaults := xa.GridMajorStyle
 				if gl.IsMinor {
 					defaults = xa.GridMinorStyle

yaxis.go

@@ -117,7 +117,7 @@ func (ya YAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, tic
 		maxy = MaxInt(maxy, ly+tbh2)
 	}
 
-	if ya.NameStyle.Show && len(ya.Name) > 0 {
+	if !ya.NameStyle.Hidden && len(ya.Name) > 0 {
 		maxx += (DefaultYAxisMargin + maxTextHeight)
 	}
 
@@ -188,7 +188,7 @@ func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, tick
 	}
 
 	nameStyle := ya.NameStyle.InheritFrom(defaults.InheritFrom(Style{TextRotationDegrees: 90}))
-	if ya.NameStyle.Show && len(ya.Name) > 0 {
+	if !ya.NameStyle.Hidden && len(ya.Name) > 0 {
 		nameStyle.GetTextOptions().WriteToRenderer(r)
 		tb := Draw.MeasureText(r, ya.Name, nameStyle)
 
@@ -209,13 +209,13 @@ func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, tick
 		Draw.Text(r, ya.Name, tx, ty, nameStyle)
 	}
 
-	if ya.Zero.Style.Show {
+	if !ya.Zero.Style.Hidden {
 		ya.Zero.Render(r, canvasBox, ra, false, Style{})
 	}
 
-	if ya.GridMajorStyle.Show || ya.GridMinorStyle.Show {
+	if !ya.GridMajorStyle.Hidden || !ya.GridMinorStyle.Hidden {
 		for _, gl := range ya.GetGridLines(ticks) {
-			if (gl.IsMinor && ya.GridMinorStyle.Show) || (!gl.IsMinor && ya.GridMajorStyle.Show) {
+			if (gl.IsMinor && !ya.GridMinorStyle.Hidden) || (!gl.IsMinor && !ya.GridMajorStyle.Hidden) {
 				defaults := ya.GridMajorStyle
 				if gl.IsMinor {
 					defaults = ya.GridMinorStyle