feat: support mulit y axis

axis.go

@@ -78,14 +78,17 @@ func NewAxis(d *Draw, data AxisDataList, style AxisOption) *axis {
 
 }
 
+// GetLabelMargin returns the label margin value
 func (as *AxisOption) GetLabelMargin() int {
 	return getDefaultInt(as.LabelMargin, 8)
 }
 
+// GetTickLength returns the tick length value
 func (as *AxisOption) GetTickLength() int {
 	return getDefaultInt(as.TickLength, 5)
 }
 
+// Style returns the style of axis
 func (as *AxisOption) Style(f *truetype.Font) chart.Style {
 	s := chart.Style{
 		ClassName:   as.ClassName,
@@ -109,6 +112,7 @@ type AxisData struct {
 }
 type AxisDataList []AxisData
 
+// TextList returns the text list of axis data
 func (l AxisDataList) TextList() []string {
 	textList := make([]string, len(l))
 	for index, item := range l {
@@ -125,6 +129,7 @@ type axisRenderOption struct {
 	modValue      int
 }
 
+// NewAxisDataListFromStringList creates a new axis data list from string list
 func NewAxisDataListFromStringList(textList []string) AxisDataList {
 	list := make(AxisDataList, len(textList))
 	for index, text := range textList {

bar_chart.go

@@ -37,7 +37,7 @@ func barChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 	if err != nil {
 		return nil, err
 	}
-	yRange := result.yRange
+	// yRange := result.yRange
 	xRange := result.xRange
 	x0, x1 := xRange.GetRange(0)
 	width := int(x1 - x0)
@@ -50,7 +50,7 @@ func barChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 	// 总的宽度-两个margin-(总数-1)的barMargin
 	barWidth := (width - 2*margin - barMargin*(seriesCount-1)) / len(opt.SeriesList)
 
-	barMaxHeight := yRange.Size
+	barMaxHeight := result.getYRange(0).Size
 	theme := NewTheme(opt.Theme)
 
 	seriesNames := opt.Legend.Data
@@ -58,6 +58,9 @@ func barChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 	r := d.Render
 
 	for i, series := range opt.SeriesList {
+		yRange := result.getYRange(series.YAxisIndex)
+		points := make([]Point, len(series.Data))
+		seriesColor := theme.GetSeriesColor(i)
 		for j, item := range series.Data {
 			x0, _ := xRange.GetRange(j)
 			x := int(x0)
@@ -67,26 +70,32 @@ func barChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 			}
 
 			h := int(yRange.getHeight(item.Value))
-			fillColor := theme.GetSeriesColor(i)
+			fillColor := seriesColor
 			if !item.Style.FillColor.IsZero() {
 				fillColor = item.Style.FillColor
 			}
-
+			top := barMaxHeight - h
 			d.Bar(chart.Box{
-				Top:    barMaxHeight - h,
+				Top:    top,
 				Left:   x,
 				Right:  x + barWidth,
 				Bottom: barMaxHeight - 1,
 			}, BarStyle{
 				FillColor: fillColor,
 			})
+			// 用于生成marker point
+			points[j] = Point{
+				// 居中的位置
+				X: x + barWidth>>1,
+				Y: top,
+			}
 			if !series.Label.Show {
 				continue
 			}
 			text := NewValueLabelFormater(seriesNames, series.Label.Formatter)(i, item.Value, -1)
 			labelStyle := chart.Style{
 				FontColor: theme.GetTextColor(),
-				FontSize:  10,
+				FontSize:  labelFontSize,
 				Font:      opt.Font,
 			}
 			if !series.Label.Color.IsZero() {
@@ -96,6 +105,12 @@ func barChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 			textBox := r.MeasureText(text)
 			d.text(text, x+(barWidth-textBox.Width())>>1, barMaxHeight-h-5)
 		}
+		markPointRender(d, markPointRenderOption{
+			FillColor: seriesColor,
+			Font:      opt.Font,
+			Points:    points,
+			Series:    &series,
+		})
 	}
 
 	return result.d, nil

chart.go

@@ -42,6 +42,8 @@ type Point struct {
 	Y int
 }
 
+const labelFontSize = 10
+
 type ChartOption struct {
 	Type            string
 	Font            *truetype.Font
@@ -49,7 +51,7 @@ type ChartOption struct {
 	Title           TitleOption
 	Legend          LegendOption
 	XAxis           XAxisOption
-	YAxis           YAxisOption
+	YAxisList       []YAxisOption
 	Width           int
 	Height          int
 	Parent          *Draw
@@ -61,6 +63,17 @@ type ChartOption struct {
 
 func (o *ChartOption) FillDefault(theme string) {
 	t := NewTheme(theme)
+	// 如果为空，初始化
+	yAxisCount := 1
+	for _, series := range o.SeriesList {
+		if series.YAxisIndex >= yAxisCount {
+			yAxisCount++
+		}
+	}
+	yAxisList := make([]YAxisOption, yAxisCount)
+	copy(yAxisList, o.YAxisList)
+	o.YAxisList = yAxisList
+
 	if o.Font == nil {
 		o.Font, _ = chart.GetDefaultFont()
 	}
@@ -136,9 +149,13 @@ func (o *ChartOption) getHeight() int {
 	return o.Height
 }
 
-func (o *ChartOption) getYRange(axisIndex int) Range {
+func (o *ChartOption) newYRange(axisIndex int) Range {
 	min := math.MaxFloat64
 	max := -math.MaxFloat64
+	if axisIndex >= len(o.YAxisList) {
+		axisIndex = 0
+	}
+	yAxis := o.YAxisList[axisIndex]
 
 	for _, series := range o.SeriesList {
 		if series.YAxisIndex != axisIndex {
@@ -155,21 +172,21 @@ func (o *ChartOption) getYRange(axisIndex int) Range {
 	}
 	min = min * 0.9
 	max = max * 1.1
-	if o.YAxis.Min != nil {
+	if yAxis.Min != nil {
-		min = *o.YAxis.Min
+		min = *yAxis.Min
 	}
-	if o.YAxis.Max != nil {
+	if yAxis.Max != nil {
-		max = *o.YAxis.Max
+		max = *yAxis.Max
 	}
 	divideCount := 6
 	// y轴分设置默认划分为6块
 	r := NewRange(min, max, divideCount)
 
 	// 由于NewRange会重新计算min max
-	if o.YAxis.Min != nil {
+	if yAxis.Min != nil {
 		r.Min = min
 	}
-	if o.YAxis.Max != nil {
+	if yAxis.Max != nil {
 		r.Max = max
 	}
 
@@ -178,11 +195,18 @@ func (o *ChartOption) getYRange(axisIndex int) Range {
 
 type basicRenderResult struct {
 	xRange     *Range
-	yRange   *Range
+	yRangeList []*Range
 	d          *Draw
 	titleBox   chart.Box
 }
 
+func (r *basicRenderResult) getYRange(index int) *Range {
+	if index >= len(r.yRangeList) {
+		index = 0
+	}
+	return r.yRangeList[index]
+}
+
 func Render(opt ChartOption) (*Draw, error) {
 	if len(opt.SeriesList) == 0 {
 		return nil, errors.New("series can not be nil")
@@ -206,7 +230,9 @@ func Render(opt ChartOption) (*Draw, error) {
 	// pie不需要axis
 	if isPieChart {
 		opt.XAxis.Hidden = true
-		opt.YAxis.Hidden = true
+		for index := range opt.YAxisList {
+			opt.YAxisList[index].Hidden = true
+		}
 	}
 	result, err := chartBasicRender(&opt)
 	if err != nil {
@@ -284,6 +310,9 @@ func chartBasicRender(opt *ChartOption) (*basicRenderResult, error) {
 	}
 
 	opt.FillDefault(opt.Theme)
+	if len(opt.YAxisList) > 2 {
+		return nil, errors.New("y axis should not be gt 2")
+	}
 	if opt.Parent == nil {
 		d.setBackground(opt.getWidth(), opt.getHeight(), opt.BackgroundColor)
 	}
@@ -299,25 +328,29 @@ func chartBasicRender(opt *ChartOption) (*basicRenderResult, error) {
 
 	if !opt.XAxis.Hidden {
 		// xAxis
-		xAxisHeight, xRange, err = drawXAxis(d, &opt.XAxis)
+		xAxisHeight, xRange, err = drawXAxis(d, &opt.XAxis, len(opt.YAxisList))
 		if err != nil {
 			return nil, err
 		}
 	}
 
-	// 暂时仅支持单一yaxis
+	yRangeList := make([]*Range, len(opt.YAxisList))
+
+	for index, yAxis := range opt.YAxisList {
 		var yRange *Range
-	if !opt.YAxis.Hidden {
+		if !yAxis.Hidden {
-		yRange, err = drawYAxis(d, opt, xAxisHeight, chart.Box{
+			yRange, err = drawYAxis(d, opt, index, xAxisHeight, chart.Box{
 				Top: titleBox.Height(),
 			})
 			if err != nil {
 				return nil, err
 			}
+			yRangeList[index] = yRange
+		}
 	}
 	return &basicRenderResult{
 		xRange:     xRange,
-		yRange:   yRange,
+		yRangeList: yRangeList,
 		d:          d,
 		titleBox:   titleBox,
 	}, nil

draw.go

@@ -173,7 +173,60 @@ func (d *Draw) pin(x, y, width int) {
 	cx := x
 	cy := y + int(r*2.5)
 	d.Render.QuadCurveTo(cx+left, cy+top, endX+left, endY+top)
-	d.Render.Fill()
+	d.Render.Stroke()
+}
+
+func (d *Draw) arrowLeft(x, y, width, height int) {
+	d.arrow(x, y, width, height, PositionLeft)
+}
+
+func (d *Draw) arrowRight(x, y, width, height int) {
+	d.arrow(x, y, width, height, PositionRight)
+}
+
+func (d *Draw) arrowTop(x, y, width, height int) {
+	d.arrow(x, y, width, height, PositionTop)
+}
+func (d *Draw) arrowBottom(x, y, width, height int) {
+	d.arrow(x, y, width, height, PositionBottom)
+}
+
+func (d *Draw) arrow(x, y, width, height int, direction string) {
+	halfWidth := width >> 1
+	halfHeight := height >> 1
+	if direction == PositionTop || direction == PositionBottom {
+		x0 := x - halfWidth
+		x1 := x0 + width
+		dy := -height / 3
+		y0 := y
+		y1 := y0 - height
+		if direction == PositionBottom {
+			y0 = y - height
+			y1 = y
+			dy = 2 * dy
+		}
+		d.moveTo(x0, y0)
+		d.lineTo(x0+halfWidth, y1)
+		d.lineTo(x1, y0)
+		d.lineTo(x0+halfWidth, y+dy)
+		d.lineTo(x0, y0)
+	} else {
+		x0 := x + width
+		x1 := x0 - width
+		y0 := y - halfHeight
+		dx := -width / 3
+		if direction == PositionRight {
+			x0 = x - width
+			dx = -dx
+			x1 = x0 + width
+		}
+		d.moveTo(x0, y0)
+		d.lineTo(x1, y0+halfHeight)
+		d.lineTo(x0, y0+height)
+		d.lineTo(x0+dx, y0+halfHeight)
+		d.lineTo(x0, y0)
+	}
+	d.Render.Stroke()
 }
 
 func (d *Draw) circle(radius float64, x, y int) {

draw_test.go

@@ -239,6 +239,7 @@ func TestDraw(t *testing.T) {
 			},
 			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 205 110\nA 100 100 90.00 0 1 105 210\nZ\" style=\"stroke-width:1;stroke:rgba(0,0,0,1.0);fill:rgba(0,0,255,1.0)\"/></svg>",
 		},
+		// pin
 		{
 			fn: func(d *Draw) {
 				chart.Style{
@@ -260,6 +261,94 @@ func TestDraw(t *testing.T) {
 			},
 			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 32 47\nA 15 15 330.00 1 1 38 47\nL 35 33\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/><path  d=\"M 20 33\nQ35,70 50,33\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/></svg>",
 		},
+		// arrow left
+		{
+			fn: func(d *Draw) {
+				chart.Style{
+					StrokeWidth: 1,
+					StrokeColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+					FillColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+				}.WriteToRenderer(d.Render)
+				d.arrowLeft(30, 30, 16, 10)
+			},
+			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 51 35\nL 35 40\nL 51 45\nL 46 40\nL 51 35\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/></svg>",
+		},
+		// arrow right
+		{
+			fn: func(d *Draw) {
+				chart.Style{
+					StrokeWidth: 1,
+					StrokeColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+					FillColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+				}.WriteToRenderer(d.Render)
+				d.arrowRight(30, 30, 16, 10)
+			},
+			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 19 35\nL 35 40\nL 19 45\nL 24 40\nL 19 35\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/></svg>",
+		},
+		// arrow top
+		{
+			fn: func(d *Draw) {
+				chart.Style{
+					StrokeWidth: 1,
+					StrokeColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+					FillColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+				}.WriteToRenderer(d.Render)
+				d.arrowTop(30, 30, 10, 16)
+			},
+			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 30 40\nL 35 24\nL 40 40\nL 35 35\nL 30 40\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/></svg>",
+		},
+		// arrow bottom
+		{
+			fn: func(d *Draw) {
+				chart.Style{
+					StrokeWidth: 1,
+					StrokeColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+					FillColor: drawing.Color{
+						R: 84,
+						G: 112,
+						B: 198,
+						A: 255,
+					},
+				}.WriteToRenderer(d.Render)
+				d.arrowBottom(30, 30, 10, 16)
+			},
+			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"400\" height=\"300\">\\n<path  d=\"M 30 24\nL 35 40\nL 40 24\nL 35 30\nL 30 24\" style=\"stroke-width:1;stroke:rgba(84,112,198,1.0);fill:rgba(84,112,198,1.0)\"/></svg>",
+		},
 	}
 	for _, tt := range tests {
 		d, err := NewDraw(DrawOption{

line_chart.go

@@ -23,8 +23,6 @@
 package charts
 
 import (
-	"math"
-
 	"github.com/wcharczuk/go-chart/v2"
 	"github.com/wcharczuk/go-chart/v2/drawing"
 )
@@ -45,36 +43,25 @@ func lineChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error)
 	seriesNames := opt.Legend.Data
 
 	r := d.Render
-	yRange := result.yRange
 	xRange := result.xRange
 	for i, series := range opt.SeriesList {
-		points := make([]Point, 0)
+		yRange := result.getYRange(series.YAxisIndex)
-		minIndex := -1
+		points := make([]Point, len(series.Data))
-		maxIndex := -1
+
-		minValue := math.MaxFloat64
-		maxValue := -math.MaxFloat64
 		for j, item := range series.Data {
-			if item.Value < minValue {
-				minIndex = j
-				minValue = item.Value
-			}
-			if item.Value > maxValue {
-				maxIndex = j
-				maxValue = item.Value
-			}
 			y := yRange.getRestHeight(item.Value)
 			x := xRange.getWidth(float64(j))
-			points = append(points, Point{
+			points[j] = Point{
 				Y: y,
 				X: x,
-			})
+			}
 			if !series.Label.Show {
 				continue
 			}
 			text := NewValueLabelFormater(seriesNames, series.Label.Formatter)(i, item.Value, -1)
 			labelStyle := chart.Style{
 				FontColor: theme.GetTextColor(),
-				FontSize:  10,
+				FontSize:  labelFontSize,
 				Font:      opt.Font,
 			}
 			if !series.Label.Color.IsZero() {
@@ -101,33 +88,12 @@ func lineChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error)
 			DotFillColor: dotFillColor,
 		})
 		// draw mark point
-		symbolSize := 30
+		markPointRender(d, markPointRenderOption{
-		if series.MarkPoint.SymbolSize > 0 {
-			symbolSize = series.MarkPoint.SymbolSize
-		}
-		for _, markPointData := range series.MarkPoint.Data {
-			p := points[minIndex]
-			value := minValue
-			switch markPointData.Type {
-			case SeriesMarkPointDataTypeMax:
-				p = points[maxIndex]
-				value = maxValue
-			}
-			chart.Style{
 			FillColor: seriesColor,
-			}.WriteToRenderer(r)
-			d.pin(p.X, p.Y-symbolSize>>1, symbolSize)
-
-			chart.Style{
-				FontColor:   NewTheme(ThemeDark).GetTextColor(),
-				FontSize:    10,
-				StrokeWidth: 1,
 			Font:      opt.Font,
-			}.WriteTextOptionsToRenderer(d.Render)
+			Points:    points,
-			text := commafWithDigits(value)
+			Series:    &series,
-			textBox := r.MeasureText(text)
+		})
-			d.text(text, p.X-textBox.Width()>>1, p.Y-symbolSize>>1-2)
-		}
 	}
 
 	return result.d, nil

mark_point.go

@@ -0,0 +1,75 @@
+// MIT License
+
+// Copyright (c) 2022 Tree Xie
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package charts
+
+import (
+	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/v2"
+	"github.com/wcharczuk/go-chart/v2/drawing"
+)
+
+type markPointRenderOption struct {
+	FillColor drawing.Color
+	Font      *truetype.Font
+	Series    *Series
+	Points    []Point
+}
+
+func markPointRender(d *Draw, opt markPointRenderOption) {
+	s := opt.Series
+	if len(s.MarkPoint.Data) == 0 {
+		return
+	}
+	points := opt.Points
+	summary := s.Summary()
+	symbolSize := s.MarkPoint.SymbolSize
+	if symbolSize == 0 {
+		symbolSize = 30
+	}
+	r := d.Render
+	// 设置填充样式
+	chart.Style{
+		FillColor: opt.FillColor,
+	}.WriteToRenderer(r)
+	// 设置文本样式
+	chart.Style{
+		FontColor:   NewTheme(ThemeDark).GetTextColor(),
+		FontSize:    10,
+		StrokeWidth: 1,
+		Font:        opt.Font,
+	}.WriteTextOptionsToRenderer(r)
+	for _, markPointData := range s.MarkPoint.Data {
+		p := points[summary.MinIndex]
+		value := summary.MinValue
+		switch markPointData.Type {
+		case SeriesMarkPointDataTypeMax:
+			p = points[summary.MaxIndex]
+			value = summary.MaxValue
+		}
+
+		d.pin(p.X, p.Y-symbolSize>>1, symbolSize)
+		text := commafWithDigits(value)
+		textBox := r.MeasureText(text)
+		d.text(text, p.X-textBox.Width()>>1, p.Y-symbolSize>>1-2)
+	}
+}

pie_chart.go

@@ -136,7 +136,7 @@ func pieChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error) {
 			r.Stroke()
 			textStyle := chart.Style{
 				FontColor: theme.GetTextColor(),
-				FontSize:  10,
+				FontSize:  labelFontSize,
 				Font:      opt.Font,
 			}
 			if !series.Label.Color.IsZero() {

range.go

@@ -40,9 +40,15 @@ func NewRange(min, max float64, divideCount int) Range {
 	// 最小单位计算
 	unit := 2
 	if r > 10 {
+		unit = 4
+	}
+	if r > 30 {
 		unit = 5
 	}
 	if r > 100 {
+		unit = 10
+	}
+	if r > 200 {
 		unit = 20
 	}
 	unit = int((r/float64(divideCount))/float64(unit))*unit + unit

range_test.go

@@ -37,12 +37,16 @@ func TestRange(t *testing.T) {
 
 	r = NewRange(0, 12, 6)
 	assert.Equal(0.0, r.Min)
-	assert.Equal(30.0, r.Max)
+	assert.Equal(24.0, r.Max)
 
 	r = NewRange(-13, 18, 6)
 	assert.Equal(-20.0, r.Min)
 	assert.Equal(40.0, r.Max)
 
+	r = NewRange(0, 150, 6)
+	assert.Equal(0.0, r.Min)
+	assert.Equal(180.0, r.Max)
+
 	r = NewRange(0, 400, 6)
 	assert.Equal(0.0, r.Min)
 	assert.Equal(480.0, r.Max)

series.go

@@ -23,6 +23,7 @@
 package charts
 
 import (
+	"math"
 	"strings"
 
 	"github.com/dustin/go-humanize"
@@ -86,6 +87,40 @@ type Series struct {
 	MarkPoint SeriesMarkPoint
 }
 
+type seriesSummary struct {
+	MaxIndex     int
+	MaxValue     float64
+	MinIndex     int
+	MinValue     float64
+	AverageValue float64
+}
+
+func (s *Series) Summary() seriesSummary {
+	minIndex := -1
+	maxIndex := -1
+	minValue := math.MaxFloat64
+	maxValue := -math.MaxFloat64
+	sum := float64(0)
+	for j, item := range s.Data {
+		if item.Value < minValue {
+			minIndex = j
+			minValue = item.Value
+		}
+		if item.Value > maxValue {
+			maxIndex = j
+			maxValue = item.Value
+		}
+		sum += item.Value
+	}
+	return seriesSummary{
+		MaxIndex:     maxIndex,
+		MaxValue:     maxValue,
+		MinIndex:     minIndex,
+		MinValue:     minValue,
+		AverageValue: sum / float64(len(s.Data)),
+	}
+}
+
 type LabelFormatter func(index int, value float64, percent float64) string
 
 func NewPieLabelFormatter(seriesNames []string, layout string) LabelFormatter {

util.go

@@ -106,7 +106,7 @@ func isFalse(flag *bool) bool {
 	return false
 }
 
-func toFloatPoint(f float64) *float64 {
+func NewFloatPoint(f float64) *float64 {
 	v := f
 	return &v
 }
@@ -118,7 +118,7 @@ func commafWithDigits(value float64) string {
 	}
 	k := float64(1000)
 	if value >= k {
-		return humanize.CommafWithDigits(value/k, decimals) + " K"
+		return humanize.CommafWithDigits(value/k, decimals) + "k"
 	}
 	return humanize.CommafWithDigits(value, decimals)
 }

xaxis.go

@@ -22,7 +22,9 @@
 
 package charts
 
-import "github.com/wcharczuk/go-chart/v2"
+import (
+	"github.com/wcharczuk/go-chart/v2"
+)
 
 type XAxisOption struct {
 	// The boundary gap on both sides of a coordinate axis.
@@ -39,16 +41,19 @@ type XAxisOption struct {
 }
 
 // drawXAxis draws x axis, and returns the height, range of if.
-func drawXAxis(p *Draw, opt *XAxisOption) (int, *Range, error) {
+func drawXAxis(p *Draw, opt *XAxisOption, yAxisCount int) (int, *Range, error) {
 	if opt.Hidden {
 		return 0, nil, nil
 	}
+	left := YAxisWidth
+	right := (yAxisCount - 1) * YAxisWidth
 	dXAxis, err := NewDraw(
 		DrawOption{
 			Parent: p,
 		},
 		PaddingOption(chart.Box{
-			Left: YAxisWidth,
+			Left:  left,
+			Right: right,
 		}),
 	)
 	if err != nil {

xaxis_test.go

@@ -81,7 +81,7 @@ func TestDrawXAxis(t *testing.T) {
 
 	for _, tt := range tests {
 		d := tt.newDraw()
-		height, _, err := drawXAxis(d, tt.newOption())
+		height, _, err := drawXAxis(d, tt.newOption(), 1)
 		assert.Nil(err)
 		assert.Equal(25, height)
 		data, err := d.Bytes()

yaxis.go

@@ -41,11 +41,11 @@ type YAxisOption struct {
 
 const YAxisWidth = 40
 
-func drawYAxis(p *Draw, opt *ChartOption, xAxisHeight int, padding chart.Box) (*Range, error) {
+func drawYAxis(p *Draw, opt *ChartOption, axisIndex, xAxisHeight int, padding chart.Box) (*Range, error) {
 	theme := NewTheme(opt.Theme)
-	yRange := opt.getYRange(0)
+	yRange := opt.newYRange(axisIndex)
 	values := yRange.Values()
-	formatter := opt.YAxis.Formatter
+	formatter := opt.YAxisList[axisIndex].Formatter
 	if len(formatter) != 0 {
 		for index, text := range values {
 			values[index] = strings.ReplaceAll(formatter, "{value}", text)
@@ -64,12 +64,21 @@ func drawYAxis(p *Draw, opt *ChartOption, xAxisHeight int, padding chart.Box) (*
 	}
 	width := NewAxis(p, data, style).measureAxis()
 
+	yAxisCount := len(opt.YAxisList)
+	boxWidth := p.Box.Width()
+	if axisIndex > 0 {
+		style.SplitLineShow = false
+		style.Position = PositionRight
+		padding.Right += (axisIndex - 1) * YAxisWidth
+	} else {
+		boxWidth = p.Box.Width() - (yAxisCount-1)*YAxisWidth
 		padding.Left += (YAxisWidth - width)
+	}
 
 	dYAxis, err := NewDraw(
 		DrawOption{
 			Parent: p,
-			Width:  p.Box.Width(),
+			Width:  boxWidth,
 			// 减去x轴的高
 			Height: p.Box.Height() - xAxisHeight,
 		},

yaxis_test.go

@@ -49,8 +49,10 @@ func TestDrawYAxis(t *testing.T) {
 			newDraw: newDraw,
 			newOption: func() *ChartOption {
 				return &ChartOption{
-					YAxis: YAxisOption{
+					YAxisList: []YAxisOption{
-						Max: toFloatPoint(20),
+						{
+							Max: NewFloatPoint(20),
+						},
 					},
 					SeriesList: []Series{
 						{
@@ -72,7 +74,7 @@ func TestDrawYAxis(t *testing.T) {
 
 	for _, tt := range tests {
 		d := tt.newDraw()
-		r, err := drawYAxis(d, tt.newOption(), tt.xAxisHeight, chart.NewBox(10, 10, 10, 10))
+		r, err := drawYAxis(d, tt.newOption(), 0, tt.xAxisHeight, chart.NewBox(10, 10, 10, 10))
 		assert.Nil(err)
 		assert.Equal(&Range{
 			divideCount: 6,