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scale_linear.go
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scale_linear.go
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package tplot
import (
"math"
)
// Linear represents a linear scale.
type ScaleLinear struct {
factory DecimalFactory
rng Range
size int
}
var _ Scale = &ScaleLinear{}
// NewLinear constructs a new linear scale.
func NewScaleLinear(factory DecimalFactory) *ScaleLinear {
return &ScaleLinear{
factory: factory,
rng: NewRange(factory),
}
}
func (a *ScaleLinear) Copy() Scale {
b := *a
return &b
}
// Size returns the scale size.
func (a *ScaleLinear) Size() int {
return a.size
}
// SetRange sets the scale range.
func (a *ScaleLinear) SetRange(rng Range) {
a.rng = rng
}
func (a *ScaleLinear) Range() Range {
return a.rng
}
// SetSize sets the size.
func (a *ScaleLinear) SetSize(size int) {
a.size = size
}
func (a *ScaleLinear) Reverse(i int) Decimal {
val := a.factory.NewFromInt64(int64(i))
return a.rng.Min.Add(val.Mul(a.step()))
}
func (a *ScaleLinear) NumDecimals() int {
step := a.step()
if step.IsZero() {
return 0
}
stepFloat := step.Float64()
numDecs := 0
if f := math.Log10(stepFloat); f < 0 {
numDecs = int(math.Abs(f))
}
return numDecs
}
func (a *ScaleLinear) step() Decimal {
step := a.factory.Zero()
if s := a.size - 1; s > 0 {
step = a.rng.Max.Sub(a.rng.Min).Div(a.factory.NewFromInt64(int64(s)))
}
return step
}
func (a *ScaleLinear) scale() Decimal {
if a.rng.Min.Equal(a.rng.Max) {
return a.factory.Zero()
}
val := a.factory.NewFromInt64(int64(a.size - 1))
return val.Div(a.rng.Max.Sub(a.rng.Min))
}
// Value returns a scaled value from decimal.
func (a *ScaleLinear) Value(v Decimal) int {
scale := a.scale()
ret := v.Sub(a.rng.Min).Mul(scale).IntPart()
return int(ret)
}