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package data
import (
"fmt"
"math"
)
import "strconv"
const maxDigits = 6
func ff(x float64) string {
minExact := strconv.FormatFloat(x, 'g', -1, 64)
fixed := strconv.FormatFloat(x, 'g', maxDigits, 64)
if len(minExact) < len(fixed) {
return minExact
}
return fixed
}
type Bin struct {
LeftInclusive float64
Right float64
RightInclusive bool
Count uint64
}
func (b *Bin) String() string {
if b.RightInclusive {
return fmt.Sprintf("[%s,%s]", ff(b.LeftInclusive), ff(b.Right))
}
return fmt.Sprintf("[%s,%s)", ff(b.LeftInclusive), ff(b.Right))
}
type Bins struct {
Number int
min, max float64
numPoints int
}
func (b *Bins) ChooseSqrt() {
b.Number = int(math.Sqrt(float64(b.numPoints)))
}
func (b *Bins) ChooseSturges() {
b.Number = int(math.Ceil(math.Log2(float64(b.numPoints))) + 1)
}
func (b *Bins) ChooseRice() {
b.Number = int(math.Ceil(2 * math.Pow(float64(b.numPoints), 1.0/3.0)))
}
func NewBins(points []float64) *Bins {
bins := new(Bins)
bins.numPoints = len(points)
bins.Number = 5
bins.min = math.Inf(1)
bins.max = math.Inf(-1)
for _, x := range points {
bins.min = math.Min(bins.min, x)
bins.max = math.Max(bins.max, x)
}
return bins
}
func (b *Bins) left(i int) float64 {
return b.min + ((b.max - b.min) / float64(b.Number) * float64(i))
}
func (b *Bins) right(i int) float64 {
return b.left(i + 1)
}
func (b *Bins) All() (out []Bin) {
if b.max == b.min {
b.Number = 1
}
for i := 0; i < b.Number; i++ {
out = append(out, Bin{
LeftInclusive: b.left(i),
Right: b.right(i),
})
}
out[b.Number-1].RightInclusive = true
return
}
func (b *Bins) Point(x float64) int {
if b.max == b.min {
return 0
}
i := int((x - b.min) / (b.max - b.min) * float64(b.Number))
if i >= b.Number {
i--
}
return i
}
func Histogram(points []float64, bins *Bins) (out []Bin) {
out = bins.All()
for _, b := range out {
b.Count = 0
}
for _, x := range points {
out[bins.Point(x)].Count++
}
return
}
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