Adding upstream version 2.1.2.

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

linear_sequence.go

@@ -0,0 +1,73 @@
+package chart
+
+// LinearRange returns an array of values representing the range from start to end, incremented by 1.0.
+func LinearRange(start, end float64) []float64 {
+	return Seq{NewLinearSequence().WithStart(start).WithEnd(end).WithStep(1.0)}.Values()
+}
+
+// LinearRangeWithStep returns the array values of a linear seq with a given start, end and optional step.
+func LinearRangeWithStep(start, end, step float64) []float64 {
+	return Seq{NewLinearSequence().WithStart(start).WithEnd(end).WithStep(step)}.Values()
+}
+
+// NewLinearSequence returns a new linear generator.
+func NewLinearSequence() *LinearSeq {
+	return &LinearSeq{step: 1.0}
+}
+
+// LinearSeq is a stepwise generator.
+type LinearSeq struct {
+	start float64
+	end   float64
+	step  float64
+}
+
+// Start returns the start value.
+func (lg LinearSeq) Start() float64 {
+	return lg.start
+}
+
+// End returns the end value.
+func (lg LinearSeq) End() float64 {
+	return lg.end
+}
+
+// Step returns the step value.
+func (lg LinearSeq) Step() float64 {
+	return lg.step
+}
+
+// Len returns the number of elements in the seq.
+func (lg LinearSeq) Len() int {
+	if lg.start < lg.end {
+		return int((lg.end-lg.start)/lg.step) + 1
+	}
+	return int((lg.start-lg.end)/lg.step) + 1
+}
+
+// GetValue returns the value at a given index.
+func (lg LinearSeq) GetValue(index int) float64 {
+	fi := float64(index)
+	if lg.start < lg.end {
+		return lg.start + (fi * lg.step)
+	}
+	return lg.start - (fi * lg.step)
+}
+
+// WithStart sets the start and returns the linear generator.
+func (lg *LinearSeq) WithStart(start float64) *LinearSeq {
+	lg.start = start
+	return lg
+}
+
+// WithEnd sets the end and returns the linear generator.
+func (lg *LinearSeq) WithEnd(end float64) *LinearSeq {
+	lg.end = end
+	return lg
+}
+
+// WithStep sets the step and returns the linear generator.
+func (lg *LinearSeq) WithStep(step float64) *LinearSeq {
+	lg.step = step
+	return lg
+}