handle zero values with error.
This commit is contained in:
parent
7163f89845
commit
7ae42ee2e1
3 changed files with 63 additions and 10 deletions
14
pie_chart.go
14
pie_chart.go
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@ -2,6 +2,7 @@ package chart
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import (
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"errors"
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"fmt"
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"io"
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"github.com/golang/freetype/truetype"
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@ -88,7 +89,10 @@ func (pc PieChart) Render(rp RendererProvider, w io.Writer) error {
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pc.drawBackground(r)
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pc.drawCanvas(r, canvasBox)
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finalValues := pc.finalizeValues(pc.Values)
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finalValues, err := pc.finalizeValues(pc.Values)
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if err != nil {
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return err
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}
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pc.drawSlices(r, canvasBox, finalValues)
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pc.drawTitle(r)
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for _, a := range pc.Elements {
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@ -158,8 +162,12 @@ func (pc PieChart) drawSlices(r Renderer, canvasBox Box, values []Value) {
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}
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}
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func (pc PieChart) finalizeValues(values []Value) []Value {
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return Values(values).Normalize()
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func (pc PieChart) finalizeValues(values []Value) ([]Value, error) {
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finalValues := Values(values).Normalize()
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if len(finalValues) == 0 {
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return nil, fmt.Errorf("pie chart must contain at least (1) non-zero value")
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}
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return finalValues, nil
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}
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func (pc PieChart) getDefaultCanvasBox() Box {
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@ -29,3 +29,41 @@ func TestPieChart(t *testing.T) {
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pie.Render(PNG, b)
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assert.NotZero(b.Len())
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}
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func TestPieChartDropsZeroValues(t *testing.T) {
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assert := assert.New(t)
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pie := PieChart{
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Canvas: Style{
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FillColor: ColorLightGray,
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},
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Values: []Value{
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{Value: 5, Label: "Blue"},
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{Value: 5, Label: "Green"},
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{Value: 0, Label: "Gray"},
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},
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}
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b := bytes.NewBuffer([]byte{})
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err := pie.Render(PNG, b)
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assert.Nil(err)
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}
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func TestPieChartAllZeroValues(t *testing.T) {
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assert := assert.New(t)
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pie := PieChart{
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Canvas: Style{
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FillColor: ColorLightGray,
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},
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Values: []Value{
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{Value: 0, Label: "Blue"},
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{Value: 0, Label: "Green"},
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{Value: 0, Label: "Gray"},
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},
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}
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b := bytes.NewBuffer([]byte{})
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err := pie.Render(PNG, b)
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assert.NotNil(err)
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}
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21
value.go
21
value.go
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@ -26,13 +26,20 @@ func (vs Values) ValuesNormalized() []float64 {
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// Normalize returns the values normalized.
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func (vs Values) Normalize() []Value {
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output := make([]Value, len(vs))
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total := Math.Sum(vs.Values()...)
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for index, v := range vs {
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output[index] = Value{
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Style: v.Style,
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Label: v.Label,
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Value: Math.RoundDown(v.Value/total, 0.0001),
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var output []Value
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var total float64
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for _, v := range vs {
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total += v.Value
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}
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for _, v := range vs {
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if v.Value > 0 {
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output = append(output, Value{
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Style: v.Style,
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Label: v.Label,
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Value: Math.RoundDown(v.Value/total, 0.0001),
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})
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}
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}
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return output
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