94 lines
2.5 KiB
Go
94 lines
2.5 KiB
Go
package chart
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import (
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"fmt"
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"math"
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)
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// LogarithmicRange represents a boundary for a set of numbers.
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type LogarithmicRange struct {
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Min float64
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Max float64
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Domain int
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Descending bool
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}
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// IsDescending returns if the range is descending.
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func (r LogarithmicRange) IsDescending() bool {
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return r.Descending
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}
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// IsZero returns if the LogarithmicRange has been set or not.
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func (r LogarithmicRange) IsZero() bool {
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return (r.Min == 0 || math.IsNaN(r.Min)) &&
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(r.Max == 0 || math.IsNaN(r.Max)) &&
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r.Domain == 0
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}
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// GetMin gets the min value for the continuous range.
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func (r LogarithmicRange) GetMin() float64 {
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return r.Min
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}
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// SetMin sets the min value for the continuous range.
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func (r *LogarithmicRange) SetMin(min float64) {
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r.Min = min
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}
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// GetMax returns the max value for the continuous range.
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func (r LogarithmicRange) GetMax() float64 {
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return r.Max
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}
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// SetMax sets the max value for the continuous range.
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func (r *LogarithmicRange) SetMax(max float64) {
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r.Max = max
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}
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// GetDelta returns the difference between the min and max value.
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func (r LogarithmicRange) GetDelta() float64 {
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return r.Max - r.Min
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}
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// GetDomain returns the range domain.
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func (r LogarithmicRange) GetDomain() int {
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return r.Domain
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}
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// SetDomain sets the range domain.
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func (r *LogarithmicRange) SetDomain(domain int) {
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r.Domain = domain
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}
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// String returns a simple string for the LogarithmicRange.
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func (r LogarithmicRange) String() string {
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return fmt.Sprintf("LogarithmicRange [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
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}
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// Translate maps a given value into the LogarithmicRange space. Modified version from ContinuousRange.
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func (r LogarithmicRange) Translate(value float64) int {
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if value < 1 {
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return 0
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}
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normalized := math.Max(value-r.Min, 1)
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ratio := math.Log10(normalized) / math.Log10(r.GetDelta())
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if r.IsDescending() {
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return r.Domain - int(math.Ceil(ratio*float64(r.Domain)))
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}
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return int(math.Ceil(ratio * float64(r.Domain)))
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}
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// GetTicks calculates the needed ticks for the axis, in log scale. Only supports Y values > 0.
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func (r LogarithmicRange) GetTicks(render Renderer, defaults Style, vf ValueFormatter) []Tick {
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var ticks []Tick
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exponentStart := int64(math.Max(0, math.Floor(math.Log10(r.Min)))) // one below min
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exponentEnd := int64(math.Max(0, math.Ceil(math.Log10(r.Max)))) // one above max
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for exp:=exponentStart; exp<=exponentEnd; exp++ {
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tickVal := math.Pow(10, float64(exp))
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ticks = append(ticks, Tick{Value: tickVal, Label: vf(tickVal)})
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}
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return ticks
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}
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