Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

seq.go

@@ -0,0 +1,275 @@
+package chart
+
+import (
+	"math"
+	"sort"
+)
+
+// ValueSequence returns a sequence for a given values set.
+func ValueSequence(values ...float64) Seq {
+	return Seq{NewArray(values...)}
+}
+
+// Sequence is a provider for values for a seq.
+type Sequence interface {
+	Len() int
+	GetValue(int) float64
+}
+
+// Seq is a utility wrapper for seq providers.
+type Seq struct {
+	Sequence
+}
+
+// Values enumerates the seq into a slice.
+func (s Seq) Values() (output []float64) {
+	if s.Len() == 0 {
+		return
+	}
+
+	output = make([]float64, s.Len())
+	for i := 0; i < s.Len(); i++ {
+		output[i] = s.GetValue(i)
+	}
+	return
+}
+
+// Each applies the `mapfn` to all values in the value provider.
+func (s Seq) Each(mapfn func(int, float64)) {
+	for i := 0; i < s.Len(); i++ {
+		mapfn(i, s.GetValue(i))
+	}
+}
+
+// Map applies the `mapfn` to all values in the value provider,
+// returning a new seq.
+func (s Seq) Map(mapfn func(i int, v float64) float64) Seq {
+	output := make([]float64, s.Len())
+	for i := 0; i < s.Len(); i++ {
+		mapfn(i, s.GetValue(i))
+	}
+	return Seq{Array(output)}
+}
+
+// FoldLeft collapses a seq from left to right.
+func (s Seq) FoldLeft(mapfn func(i int, v0, v float64) float64) (v0 float64) {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	if s.Len() == 1 {
+		return s.GetValue(0)
+	}
+
+	v0 = s.GetValue(0)
+	for i := 1; i < s.Len(); i++ {
+		v0 = mapfn(i, v0, s.GetValue(i))
+	}
+	return
+}
+
+// FoldRight collapses a seq from right to left.
+func (s Seq) FoldRight(mapfn func(i int, v0, v float64) float64) (v0 float64) {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	if s.Len() == 1 {
+		return s.GetValue(0)
+	}
+
+	v0 = s.GetValue(s.Len() - 1)
+	for i := s.Len() - 2; i >= 0; i-- {
+		v0 = mapfn(i, v0, s.GetValue(i))
+	}
+	return
+}
+
+// Min returns the minimum value in the seq.
+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 seq.
+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 seq sorted in ascending order.
+// This fully enumerates the seq.
+func (s Seq) Sort() Seq {
+	if s.Len() == 0 {
+		return s
+	}
+	values := s.Values()
+	sort.Float64s(values)
+	return Seq{Array(values)}
+}
+
+// Reverse reverses the sequence
+func (s Seq) Reverse() Seq {
+	if s.Len() == 0 {
+		return s
+	}
+
+	values := s.Values()
+	valuesLen := len(values)
+	valuesLen1 := len(values) - 1
+	valuesLen2 := valuesLen >> 1
+	var i, j float64
+	for index := 0; index < valuesLen2; index++ {
+		i = values[index]
+		j = values[valuesLen1-index]
+		values[index] = j
+		values[valuesLen1-index] = i
+	}
+
+	return Seq{Array(values)}
+}
+
+// Median returns the median or middle value in the sorted seq.
+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.
+func (s Seq) Sum() (accum float64) {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	for i := 0; i < s.Len(); i++ {
+		accum += s.GetValue(i)
+	}
+	return
+}
+
+// Average returns the float average of the values in the buffer.
+func (s Seq) Average() float64 {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	return s.Sum() / float64(s.Len())
+}
+
+// Variance computes the variance of the buffer.
+func (s Seq) Variance() float64 {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	m := s.Average()
+	var variance, v float64
+	for i := 0; i < s.Len(); i++ {
+		v = s.GetValue(i)
+		variance += (v - m) * (v - m)
+	}
+
+	return variance / float64(s.Len())
+}
+
+// StdDev returns the standard deviation.
+func (s Seq) StdDev() float64 {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	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{Array(output)}
+}