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package plot
import (
"bytes"
"math"
"github.com/sgreben/jp/pkg/draw"
)
// LineChart is a line chart
type LineChart struct{ draw.Canvas }
// NewLineChart returns a new line chart
func NewLineChart(canvas draw.Canvas) *LineChart { return &LineChart{canvas} }
func (c *LineChart) drawAxes(paddingX, paddingY int, minX, maxX, minY, maxY float64) {
buffer := c.GetBuffer()
// X axis
buffer.SetRow(1, paddingX, buffer.Width, draw.HorizontalLine)
// Y axis
buffer.SetColumn(1, buffer.Height, paddingX, draw.VerticalLine)
// Corner
buffer.Set(1, paddingX, draw.CornerBottomLeft)
// Labels
buffer.WriteRight(1, 1, Ff(minY))
buffer.WriteLeft(buffer.Height-1, paddingX, Ff(maxY))
buffer.WriteRight(0, paddingX, Ff(minX))
buffer.WriteLeft(0, buffer.Width, Ff(maxX))
}
// Draw implements Chart
func (c *LineChart) Draw(data *DataTable) string {
var scaleY, scaleX float64
var prevX, prevY int
minX, maxX, minY, maxY := minMax(data)
minLabelWidth := len(Ff(minY))
maxLabelWidth := len(Ff(maxY))
paddingX := minLabelWidth + 1
paddingY := 2
if minLabelWidth < maxLabelWidth {
paddingX = maxLabelWidth + 1
}
chartWidth := c.Size().Width - (paddingX+1)*c.RuneSize().Width
chartHeight := c.Size().Height - paddingY*c.RuneSize().Height
scaleX = float64(chartWidth) / (maxX - minX)
scaleY = float64(chartHeight) / (maxY - minY)
first := true
for _, point := range data.Rows {
if len(point) < 2 {
continue
}
x := int((point[0]-minX)*scaleX + float64((paddingX+1)*c.RuneSize().Width))
y := int((point[1]-minY)*scaleY + float64(paddingY*c.RuneSize().Height))
if first {
first = false
prevX = x
prevY = y
}
if prevX <= x {
c.DrawLine(prevY, prevX, y, x)
}
prevX = x
prevY = y
}
c.drawAxes(paddingX, paddingY, minX, maxX, minY, maxY)
b := bytes.NewBuffer(nil)
c.GetBuffer().Render(b)
return b.String()
}
func roundDownToPercentOfRange(x, d float64) float64 {
return math.Floor((x*(100-math.Copysign(5, x)))/d) * d / 100
}
func roundUpToPercentOfRange(x, d float64) float64 {
return math.Ceil((x*105)/d) * d / 100
}
func minMax(data *DataTable) (minX, maxX, minY, maxY float64) {
minX, minY = math.Inf(1), math.Inf(1)
maxX, maxY = math.Inf(-1), math.Inf(-1)
for _, r := range data.Rows {
if len(r) < 2 {
continue
}
maxX = math.Max(maxX, r[0])
minX = math.Min(minX, r[0])
maxY = math.Max(maxY, r[1])
minY = math.Min(minY, r[1])
}
yRange := maxY - minY
minY = roundDownToPercentOfRange(minY, yRange)
maxY = roundUpToPercentOfRange(maxY, yRange)
return
}
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