big api overhauls.

sequence.go

@@ -0,0 +1,55 @@
+package chart
+
+import (
+	"math/rand"
+	"time"
+)
+
+var (
+	// Sequence contains some sequence utilities.
+	// These utilities can be useful for generating test data.
+	Sequence = &sequence{}
+)
+
+type sequence struct{}
+
+// Float64 produces an array of floats from [start,end] by optional steps.
+func (s sequence) Float64(start, end float64, steps ...float64) []float64 {
+	var values []float64
+	step := 1.0
+	if len(steps) > 0 {
+		step = steps[0]
+	}
+
+	if start < end {
+		for x := start; x <= end; x += step {
+			values = append(values, x)
+		}
+	} else {
+		for x := start; x >= end; x = x - step {
+			values = append(values, x)
+		}
+	}
+	return values
+}
+
+// Random generates a fixed length sequence of random values between (0, scale).
+func (s sequence) Random(samples int, scale float64) []float64 {
+	rnd := rand.New(rand.NewSource(time.Now().Unix()))
+	values := make([]float64, samples)
+
+	for x := 0; x < samples; x++ {
+		values[x] = rnd.Float64() * scale
+	}
+
+	return values
+}
+
+// Days generates a sequence of timestamps by day, from -days to today.
+func (s sequence) Days(days int) []time.Time {
+	var values []time.Time
+	for day := days; day >= 0; day-- {
+		values = append(values, time.Now().AddDate(0, 0, -day))
+	}
+	return values
+}