This commit is contained in:
Will Charczuk 2017-05-01 22:18:52 -07:00
parent 41d81c82db
commit c0fc2baa50
4 changed files with 176 additions and 3 deletions

View File

@ -1,6 +1,14 @@
package sequence package sequence
import "math" import (
"math"
"sort"
)
// New returns a new sequence.
func New(values ...float64) Seq {
return Seq{Provider: Array(values)}
}
// Provider is a provider for values for a sequence. // Provider is a provider for values for a sequence.
type Provider interface { type Provider interface {
@ -73,6 +81,88 @@ func (s Seq) FoldRight(mapfn func(i int, v0, v float64) float64) (v0 float64) {
return return
} }
// Min returns the minimum value in the sequence.
func (s Seq) Min() float64 {
if s.Len() == 0 {
return 0
}
min := s.GetValue(0)
var value float64
for i := 1; i < s.Len(); i++ {
value = s.GetValue(i)
if value < min {
min = value
}
}
return min
}
// Max returns the maximum value in the sequence.
func (s Seq) Max() float64 {
if s.Len() == 0 {
return 0
}
max := s.GetValue(0)
var value float64
for i := 1; i < s.Len(); i++ {
value = s.GetValue(i)
if value > max {
max = value
}
}
return max
}
// MinMax returns the minimum and the maximum in one pass.
func (s Seq) MinMax() (min, max float64) {
if s.Len() == 0 {
return
}
min = s.GetValue(0)
max = min
var value float64
for i := 1; i < s.Len(); i++ {
value = s.GetValue(i)
if value < min {
min = value
}
if value > max {
max = value
}
}
return
}
// Sort returns the sequence sorted in ascending order.
// This fully enumerates the sequence.
func (s Seq) Sort() Seq {
if s.Len() == 0 {
return s
}
values := s.Array()
sort.Float64s(values)
return Seq{Provider: Array(values)}
}
// Median returns the median or middle value in the sorted sequence.
func (s Seq) Median() (median float64) {
l := s.Len()
if l == 0 {
return
}
sorted := s.Sort()
if l%2 == 0 {
v0 := sorted.GetValue(l/2 - 1)
v1 := sorted.GetValue(l/2 + 1)
median = (v0 + v1) / 2
} else {
median = float64(sorted.GetValue(l << 1))
}
return
}
// Sum adds all the elements of a series together. // Sum adds all the elements of a series together.
func (s Seq) Sum() (accum float64) { func (s Seq) Sum() (accum float64) {
if s.Len() == 0 { if s.Len() == 0 {
@ -118,3 +208,43 @@ func (s Seq) StdDev() float64 {
return math.Pow(s.Variance(), 0.5) return math.Pow(s.Variance(), 0.5)
} }
//Percentile finds the relative standing in a slice of floats.
// `percent` should be given on the interval [0,1.0).
func (s Seq) Percentile(percent float64) (percentile float64) {
l := s.Len()
if l == 0 {
return 0
}
if percent < 0 || percent > 1.0 {
panic("percent out of range [0.0, 1.0)")
}
sorted := s.Sort()
index := percent * float64(l)
if index == float64(int64(index)) {
i := f64i(index)
ci := sorted.GetValue(i - 1)
c := sorted.GetValue(i)
percentile = (ci + c) / 2.0
} else {
i := f64i(index)
percentile = sorted.GetValue(i)
}
return percentile
}
// Normalize maps every value to the interval [0, 1.0).
func (s Seq) Normalize() Seq {
min, max := s.MinMax()
delta := max - min
output := make([]float64, s.Len())
for i := 0; i < s.Len(); i++ {
output[i] = (s.GetValue(i) - min) / delta
}
return Seq{Provider: Array(output)}
}

View File

@ -81,3 +81,14 @@ func TestSequenceVariance(t *testing.T) {
values := Seq{NewArray(1, 2, 3, 4, 5)} values := Seq{NewArray(1, 2, 3, 4, 5)}
assert.Equal(2, values.Variance()) assert.Equal(2, values.Variance())
} }
func TestSequenceNormalize(t *testing.T) {
assert := assert.New(t)
normalized := New(1, 2, 3, 4, 5).Normalize().Array()
assert.NotEmpty(normalized)
assert.Len(normalized, 5)
assert.Equal(0, normalized[0])
assert.Equal(1, normalized[4])
}

32
sequence/util.go Normal file
View File

@ -0,0 +1,32 @@
package sequence
import "math"
func round(input float64, places int) (rounded float64) {
if math.IsNaN(input) {
return 0.0
}
sign := 1.0
if input < 0 {
sign = -1
input *= -1
}
precision := math.Pow(10, float64(places))
digit := input * precision
_, decimal := math.Modf(digit)
if decimal >= 0.5 {
rounded = math.Ceil(digit)
} else {
rounded = math.Floor(digit)
}
return rounded / precision * sign
}
func f64i(value float64) int {
r := round(value, 0)
return int(r)
}

View File

@ -47,7 +47,7 @@ func (m mathUtil) MinAndMax(values ...float64) (min float64, max float64) {
} }
min = values[0] min = values[0]
max = values[0] max = values[0]
for _, v := range values { for _, v := range values[1:] {
if max < v { if max < v {
max = v max = v
} }
@ -68,7 +68,7 @@ func (m mathUtil) MinAndMaxOfTime(values ...time.Time) (min time.Time, max time.
min = values[0] min = values[0]
max = values[0] max = values[0]
for _, v := range values { for _, v := range values[1:] {
if max.Before(v) { if max.Before(v) {
max = v max = v
} }