adding validation.

_examples/twopoint/main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"bytes"
+	"log"
+	"os"
+	//"time"
+	"github.com/wcharczuk/go-chart" //exposes "chart"
+)
+
+func main() {
+
+	var b float64
+	b = 1000
+
+	ts1 := chart.ContinuousSeries{ //TimeSeries{
+		Name: "Time Series",
+		Style: chart.Style{
+			Show: true,
+		},
+
+		//XValues: []time.Time{time.Unix(3*b,0),time.Unix(4*b,0),time.Unix(5*b,0),time.Unix(6*b,0),time.Unix(7*b,0),time.Unix(8*b,0),time.Unix(9*b,0),time.Unix(10*b,0)},
+		XValues: []float64{10 * b, 20 * b, 30 * b, 40 * b, 50 * b, 60 * b, 70 * b, 80 * b},
+		YValues: []float64{1.0, 2.0, 30.0, 4.0, 50.0, 6.0, 7.0, 88.0},
+	}
+
+	ts2 := chart.ContinuousSeries{ //TimeSeries{
+		Style: chart.Style{
+			Show:        true,
+			StrokeColor: chart.GetDefaultColor(1),
+		},
+
+		XValues: []float64{10 * b, 20 * b, 30 * b, 40 * b, 50 * b, 60 * b, 70 * b, 80 * b},
+		YValues: []float64{15.0, 52.0, 30.0, 42.0, 50.0, 26.0, 77.0, 38.0},
+	}
+
+	graph := chart.Chart{
+
+		XAxis: chart.XAxis{
+			Name:           "The XAxis",
+			NameStyle:      chart.StyleShow(),
+			Style:          chart.StyleShow(),
+			ValueFormatter: chart.TimeMinuteValueFormatter, //TimeHourValueFormatter,
+		},
+
+		YAxis: chart.YAxis{
+			Name:      "The YAxis",
+			NameStyle: chart.StyleShow(),
+			Style:     chart.StyleShow(),
+		},
+
+		Series: []chart.Series{
+			ts1,
+			ts2,
+		},
+	}
+
+	buffer := bytes.NewBuffer([]byte{})
+	err := graph.Render(chart.PNG, buffer)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fo, err := os.Create("output.png")
+	if err != nil {
+		panic(err)
+	}
+
+	if _, err := fo.Write(buffer.Bytes()); err != nil {
+		panic(err)
+	}
+}

annotation_series.go

@@ -1,6 +1,9 @@
 package chart
 
-import "math"
+import (
+	"fmt"
+	"math"
+)
 
 // AnnotationSeries is a series of labels on the chart.
 type AnnotationSeries struct {
@@ -73,3 +76,11 @@ func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Rang
 		}
 	}
 }
+
+// Validate validates the series.
+func (as AnnotationSeries) Validate() error {
+	if len(as.Annotations) == 0 {
+		return fmt.Errorf("annotation series requires annotations to be set and not empty")
+	}
+	return nil
+}

bollinger_band_series.go

@@ -1,6 +1,9 @@
 package chart
 
-import "math"
+import (
+	"fmt"
+	"math"
+)
 
 // 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.
@@ -147,3 +150,11 @@ func (bbs BollingerBandsSeries) getVariance(valueBuffer *RingBuffer) float64 {
 func (bbs BollingerBandsSeries) getStdDev(valueBuffer *RingBuffer) float64 {
 	return math.Pow(bbs.getVariance(valueBuffer), 0.5)
 }
+
+// Validate validates the series.
+func (bbs BollingerBandsSeries) Validate() error {
+	if bbs.InnerSeries == nil {
+		return fmt.Errorf("bollinger bands series requires InnerSeries to be set")
+	}
+	return nil
+}

chart.go

@@ -132,6 +132,17 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 	return r.Save(w)
 }
 
+func (c Chart) validateSeries() error {
+	var err error
+	for _, s := range c.Series {
+		err = s.Validate()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 	var minx, maxx float64 = math.MaxFloat64, -math.MaxFloat64
 	var miny, maxy float64 = math.MaxFloat64, -math.MaxFloat64

concat_series.go

@@ -30,3 +30,15 @@ func (cs ConcatSeries) GetValue(index int) (x, y float64) {
 	}
 	return
 }
+
+// Validate validates the series.
+func (cs ConcatSeries) Validate() error {
+	var err error
+	for _, s := range cs {
+		err = s.Validate()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

continuous_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 // ContinuousSeries represents a line on a chart.
 type ContinuousSeries struct {
 	Name  string
@@ -64,3 +66,15 @@ func (cs ContinuousSeries) Render(r Renderer, canvasBox Box, xrange, yrange Rang
 	style := cs.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, cs)
 }
+
+// Validate validates the series.
+func (cs ContinuousSeries) Validate() error {
+	if len(cs.XValues) == 0 {
+		return fmt.Errorf("continuous series must have xvalues set")
+	}
+
+	if len(cs.YValues) == 0 {
+		return fmt.Errorf("continuous series must have yvalues set")
+	}
+	return nil
+}

continuous_series_test.go

@@ -47,3 +47,26 @@ func TestContinuousSeriesValueFormatter(t *testing.T) {
 	assert.Equal("0.100000 foo", xf(0.1))
 	assert.Equal("0.100000 bar", yf(0.1))
 }
+
+func TestContinuousSeriesValidate(t *testing.T) {
+	assert := assert.New(t)
+
+	cs := ContinuousSeries{
+		Name:    "Test Series",
+		XValues: Sequence.Float64(1.0, 10.0),
+		YValues: Sequence.Float64(1.0, 10.0),
+	}
+	assert.Nil(cs.Validate())
+
+	cs = ContinuousSeries{
+		Name:    "Test Series",
+		XValues: Sequence.Float64(1.0, 10.0),
+	}
+	assert.NotNil(cs.Validate())
+
+	cs = ContinuousSeries{
+		Name:    "Test Series",
+		YValues: Sequence.Float64(1.0, 10.0),
+	}
+	assert.NotNil(cs.Validate())
+}

ema_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 const (
 	// DefaultEMAPeriod is the default EMA period used in the sigma calculation.
 	DefaultEMAPeriod = 12
@@ -99,3 +101,11 @@ func (ema *EMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, de
 	style := ema.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, ema)
 }
+
+// Validate validates the series.
+func (ema *EMASeries) Validate() error {
+	if ema.InnerSeries == nil {
+		return fmt.Errorf("ema series requires InnerSeries to be set")
+	}
+	return nil
+}

histogram_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 // 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.
@@ -55,3 +57,11 @@ func (hs HistogramSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range
 	style := hs.Style.InheritFrom(defaults)
 	Draw.HistogramSeries(r, canvasBox, xrange, yrange, style, hs)
 }
+
+// Validate validates the series.
+func (hs HistogramSeries) Validate() error {
+	if hs.InnerSeries == nil {
+		return fmt.Errorf("histogram series requires InnerSeries to be set")
+	}
+	return nil
+}

image_writer.go

@@ -38,5 +38,5 @@ func (ir *ImageWriter) Image() (image.Image, error) {
 	if ir.contents != nil && ir.contents.Len() > 0 {
 		return png.Decode(ir.contents)
 	}
-	return nil, errors.New("No valid sources for image data, cannot continue.")
+	return nil, errors.New("no valid sources for image data, cannot continue")
 }

linear_regression_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 // LinearRegressionSeries is a series that plots the n-nearest neighbors
 // linear regression for the values.
 type LinearRegressionSeries struct {
@@ -130,3 +132,11 @@ func (lrs *LinearRegressionSeries) Render(r Renderer, canvasBox Box, xrange, yra
 	style := lrs.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, lrs)
 }
+
+// Validate validates the series.
+func (lrs *LinearRegressionSeries) Validate() error {
+	if lrs.InnerSeries == nil {
+		return fmt.Errorf("linear regression series requires InnerSeries to be set")
+	}
+	return nil
+}

macd_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 const (
 	// DefaultMACDPeriodPrimary is the long window.
 	DefaultMACDPeriodPrimary = 26
@@ -287,3 +289,11 @@ func (macdl *MACDLineSeries) Render(r Renderer, canvasBox Box, xrange, yrange Ra
 	style := macdl.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, macdl)
 }
+
+// Validate validates the series.
+func (macdl *MACDLineSeries) Validate() error {
+	if macdl.InnerSeries == nil {
+		return fmt.Errorf("macd line series requires InnerSeries to be set")
+	}
+	return nil
+}

min_max_series.go

@@ -1,6 +1,9 @@
 package chart
 
-import "math"
+import (
+	"fmt"
+	"math"
+)
 
 // MinSeries draws a horizontal line at the minimum value of the inner series.
 type MinSeries struct {
@@ -60,6 +63,14 @@ func (ms *MinSeries) ensureMinValue() {
 	}
 }
 
+// Validate validates the series.
+func (ms *MinSeries) Validate() error {
+	if ms.InnerSeries == nil {
+		return fmt.Errorf("min series requires InnerSeries to be set")
+	}
+	return nil
+}
+
 // MaxSeries draws a horizontal line at the maximum value of the inner series.
 type MaxSeries struct {
 	Name        string
@@ -117,3 +128,11 @@ func (ms *MaxSeries) ensureMaxValue() {
 		ms.maxValue = &maxValue
 	}
 }
+
+// Validate validates the series.
+func (ms *MaxSeries) Validate() error {
+	if ms.InnerSeries == nil {
+		return fmt.Errorf("max series requires InnerSeries to be set")
+	}
+	return nil
+}

pie_chart.go

@@ -66,7 +66,7 @@ func (pc PieChart) GetHeight() int {
 // Render renders the chart with the given renderer to the given io.Writer.
 func (pc PieChart) Render(rp RendererProvider, w io.Writer) error {
 	if len(pc.Values) == 0 {
-		return errors.New("Please provide at least one value.")
+		return errors.New("please provide at least one value")
 	}
 
 	r, err := rp(pc.GetWidth(), pc.GetHeight())

series.go

@@ -5,5 +5,6 @@ type Series interface {
 	GetName() string
 	GetYAxis() YAxisType
 	GetStyle() Style
+	Validate() error
 	Render(r Renderer, canvasBox Box, xrange, yrange Range, s Style)
 }

sma_series.go

@@ -1,5 +1,7 @@
 package chart
 
+import "fmt"
+
 const (
 	// DefaultSimpleMovingAveragePeriod is the default number of values to average.
 	DefaultSimpleMovingAveragePeriod = 16
@@ -88,3 +90,11 @@ func (sma SMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, def
 	style := sma.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, sma)
 }
+
+// Validate validates the series.
+func (sma SMASeries) Validate() error {
+	if sma.InnerSeries == nil {
+		return fmt.Errorf("sma series requires InnerSeries to be set")
+	}
+	return nil
+}

stacked_bar_chart.go

@@ -94,7 +94,7 @@ func (sbc StackedBarChart) GetBarSpacing() int {
 // Render renders the chart with the given renderer to the given io.Writer.
 func (sbc StackedBarChart) Render(rp RendererProvider, w io.Writer) error {
 	if len(sbc.Bars) == 0 {
-		return errors.New("Please provide at least one bar.")
+		return errors.New("please provide at least one bar")
 	}
 
 	r, err := rp(sbc.GetWidth(), sbc.GetHeight())

time_series.go

@@ -1,6 +1,9 @@
 package chart
 
-import "time"
+import (
+	"fmt"
+	"time"
+)
 
 // TimeSeries is a line on a chart.
 type TimeSeries struct {
@@ -59,3 +62,15 @@ func (ts TimeSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, def
 	style := ts.Style.InheritFrom(defaults)
 	Draw.LineSeries(r, canvasBox, xrange, yrange, style, ts)
 }
+
+// Validate validates the series.
+func (ts TimeSeries) Validate() error {
+	if len(ts.XValues) == 0 {
+		return fmt.Errorf("time series must have xvalues set")
+	}
+
+	if len(ts.YValues) == 0 {
+		return fmt.Errorf("time series must have yvalues set")
+	}
+	return nil
+}

time_series_test.go

@@ -28,3 +28,42 @@ func TestTimeSeriesGetValue(t *testing.T) {
 	assert.NotZero(x0)
 	assert.Equal(1.0, y0)
 }
+
+func TestTimeSeriesValidate(t *testing.T) {
+	assert := assert.New(t)
+
+	cs := TimeSeries{
+		Name: "Test Series",
+		XValues: []time.Time{
+			time.Now().AddDate(0, 0, -5),
+			time.Now().AddDate(0, 0, -4),
+			time.Now().AddDate(0, 0, -3),
+			time.Now().AddDate(0, 0, -2),
+			time.Now().AddDate(0, 0, -1),
+		},
+		YValues: []float64{
+			1.0, 2.0, 3.0, 4.0, 5.0,
+		},
+	}
+	assert.Nil(cs.Validate())
+
+	cs = TimeSeries{
+		Name: "Test Series",
+		XValues: []time.Time{
+			time.Now().AddDate(0, 0, -5),
+			time.Now().AddDate(0, 0, -4),
+			time.Now().AddDate(0, 0, -3),
+			time.Now().AddDate(0, 0, -2),
+			time.Now().AddDate(0, 0, -1),
+		},
+	}
+	assert.NotNil(cs.Validate())
+
+	cs = TimeSeries{
+		Name: "Test Series",
+		YValues: []float64{
+			1.0, 2.0, 3.0, 4.0, 5.0,
+		},
+	}
+	assert.NotNil(cs.Validate())
+}