snapshot.

sequence/array.go

@@ -0,0 +1,14 @@
+package sequence
+
+// Array is a wrapper for an array of floats that implements `ValuesProvider`.
+type Array []float64
+
+// Len returns the value provider length.
+func (a Array) Len() int {
+	return len(a)
+}
+
+// GetValue returns the value at a given index.
+func (a Array) GetValue(index int) float64 {
+	return a[index]
+}

sequence/buffer.go

@@ -1,4 +1,4 @@
-package util
+package sequence
 
 import (
 	"fmt"

sequence/buffer_test.go

@@ -1,4 +1,4 @@
-package util
+package sequence
 
 import (
 	"testing"
@@ -6,10 +6,10 @@ import (
 	"github.com/blendlabs/go-assert"
 )
 
-func TestValueBuffer(t *testing.T) {
+func TestBuffer(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewValueBuffer()
+	buffer := NewBuffer()
 
 	buffer.Enqueue(1)
 	assert.Equal(1, buffer.Len())
@@ -100,10 +100,10 @@ func TestValueBuffer(t *testing.T) {
 	assert.Zero(buffer.PeekBack())
 }
 
-func TestRingBufferClear(t *testing.T) {
+func TestBufferClear(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewValueBuffer()
+	buffer := NewBuffer()
 	buffer.Enqueue(1)
 	buffer.Enqueue(1)
 	buffer.Enqueue(1)
@@ -121,10 +121,10 @@ func TestRingBufferClear(t *testing.T) {
 	assert.Zero(buffer.PeekBack())
 }
 
-func TestRingBufferAsSlice(t *testing.T) {
+func TestBufferArray(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewValueBuffer()
+	buffer := NewBuffer()
 	buffer.Enqueue(1)
 	buffer.Enqueue(2)
 	buffer.Enqueue(3)
@@ -140,10 +140,10 @@ func TestRingBufferAsSlice(t *testing.T) {
 	assert.Equal(5, contents[4])
 }
 
-func TestRingBufferEach(t *testing.T) {
+func TestBufferEach(t *testing.T) {
 	assert := assert.New(t)
 
-	buffer := NewValueBuffer()
+	buffer := NewBuffer()
 
 	for x := 1; x < 17; x++ {
 		buffer.Enqueue(float64(x))
@@ -159,10 +159,10 @@ func TestRingBufferEach(t *testing.T) {
 	assert.Equal(16, called)
 }
 
-func TestNewValueBuffer(t *testing.T) {
+func TestNewBuffer(t *testing.T) {
 	assert := assert.New(t)
 
-	empty := NewValueBuffer()
+	empty := NewBuffer()
 	assert.NotNil(empty)
 	assert.Zero(empty.Len())
 	assert.Equal(valueBufferDefaultCapacity, empty.Capacity())
@@ -170,13 +170,24 @@ func TestNewValueBuffer(t *testing.T) {
 	assert.Zero(empty.PeekBack())
 }
 
-func TestNewValueBufferWithValues(t *testing.T) {
+func TestNewBufferWithValues(t *testing.T) {
 	assert := assert.New(t)
 
-	values := NewValueBuffer(1, 2, 3, 4)
+	values := NewBuffer(1, 2, 3, 4, 5)
 	assert.NotNil(values)
-	assert.Equal(4, values.Len())
+	assert.Equal(5, values.Len())
 	assert.Equal(valueBufferDefaultCapacity, values.Capacity())
 	assert.Equal(1, values.Peek())
-	assert.Equal(4, values.PeekBack())
+	assert.Equal(5, values.PeekBack())
+}
+
+func TestBufferGrowth(t *testing.T) {
+	assert := assert.New(t)
+
+	values := NewBuffer(1, 2, 3, 4, 5)
+	for i := 0; i < 1<<10; i++ {
+		values.Enqueue(float64(i))
+	}
+
+	assert.Equal(1<<10-1, values.PeekBack())
 }

sequence/generate.go

@@ -1,4 +1,4 @@
-package util
+package sequence
 
 import (
 	"math/rand"
@@ -18,7 +18,7 @@ type generate struct {
 }
 
 // Values produces an array of floats from [start,end] by optional steps.
-func (g generate) Values(start, end float64, steps ...float64) Sequence {
+func (g generate) Values(start, end float64, steps ...float64) Seq {
 	var values []float64
 	step := 1.0
 	if len(steps) > 0 {
@@ -34,22 +34,22 @@ func (g generate) Values(start, end float64, steps ...float64) Sequence {
 			values = append(values, x)
 		}
 	}
-	return Sequence{Array(values)}
+	return Seq{Array(values)}
 }
 
 // Random generates a fixed length sequence of random values between (0, scale).
-func (g generate) RandomValues(samples int, scale float64) Sequence {
+func (g generate) RandomValues(samples int, scale float64) Seq {
 	values := make([]float64, samples)
 
 	for x := 0; x < samples; x++ {
 		values[x] = g.rnd.Float64() * scale
 	}
 
-	return Sequence{Array(values)}
+	return Seq{Array(values)}
 }
 
 // Random generates a fixed length sequence of random values with a given average, above and below that average by (-scale, scale)
-func (g generate) RandomValuesWithAverage(samples int, average, scale float64) Sequence {
+func (g generate) RandomValuesWithAverage(samples int, average, scale float64) Seq {
 	values := make([]float64, samples)
 
 	for x := 0; x < samples; x++ {
@@ -57,5 +57,5 @@ func (g generate) RandomValuesWithAverage(samples int, average, scale float64) S
 		values[x] = average + jitter
 	}
 
-	return Sequence{Array(values)}
+	return Seq{Array(values)}
 }

sequence/generate_test.go

@@ -1,4 +1,4 @@
-package util
+package sequence
 
 import (
 	"testing"

sequence/linear.go

@@ -0,0 +1,41 @@
+package sequence
+
+// NewLinear returns a new linear generator.
+func NewLinear() *Linear {
+	return &Linear{}
+}
+
+// Linear is a stepwise generator.
+type Linear struct {
+	offset float64
+	limit  float64
+	step   float64
+}
+
+// Len returns the number of elements in the sequence.
+func (lg Linear) Len() int {
+	return int((lg.limit - lg.offset) / lg.step)
+}
+
+// GetValue returns the value at a given index.
+func (lg Linear) GetValue(index int) float64 {
+	return lg.offset + (float64(index) * lg.step)
+}
+
+// WithOffset sets the offset and returns the linear generator.
+func (lg *Linear) WithOffset(offset float64) *Linear {
+	lg.offset = offset
+	return lg
+}
+
+// WithLimit sets the step and returns the linear generator.
+func (lg *Linear) WithLimit(limit float64) *Linear {
+	lg.limit = limit
+	return lg
+}
+
+// WithStep sets the step and returns the linear generator.
+func (lg *Linear) WithStep(step float64) *Linear {
+	lg.step = step
+	return lg
+}

sequence/random.go

@@ -0,0 +1,21 @@
+package sequence
+
+import "math/rand"
+
+type Random struct {
+	rnd     *rand.Rand
+	scale   *float64
+	average *float64
+	len     int
+}
+
+func (r *Random) Len() int {
+	return r.len
+}
+
+func (r *Random) GetValue(_ int) float64 {
+	if r.scale != nil {
+		return r.rnd.Float64() * *r.scale
+	}
+	return r.rnd.Float64()
+}

sequence/sequence.go

@@ -1,20 +1,20 @@
-package util
+package sequence
 
 import "math"
 
-// SequenceProvider is a provider for values for a sequence.
+// Provider is a provider for values for a sequence.
-type SequenceProvider interface {
+type Provider interface {
 	Len() int
 	GetValue(int) float64
 }
 
-// Sequence is a utility wrapper for sequence providers.
+// Seq is a utility wrapper for sequence providers.
-type Sequence struct {
+type Seq struct {
-	SequenceProvider
+	Provider
 }
 
 // Each applies the `mapfn` to all values in the value provider.
-func (s Sequence) Each(mapfn func(int, float64)) {
+func (s Seq) Each(mapfn func(int, float64)) {
 	for i := 0; i < s.Len(); i++ {
 		mapfn(i, s.GetValue(i))
 	}
@@ -22,29 +22,62 @@ func (s Sequence) Each(mapfn func(int, float64)) {
 
 // Map applies the `mapfn` to all values in the value provider,
 // returning a new sequence.
-func (s Sequence) Map(mapfn func(i int, v float64) float64) Sequence {
+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 Sequence{Array(output)}
+	return Seq{Array(output)}
 }
 
-// Average returns the float average of the values in the buffer.
+// FoldLeft collapses a sequence from left to right.
-func (s Sequence) Average() float64 {
+func (s Seq) FoldLeft(mapfn func(i int, v0, v float64) float64) (v0 float64) {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	v0 = s.GetValue(0)
+	for i := 1; i < s.Len(); i++ {
+		v0 = mapfn(i, v0, s.GetValue(i))
+	}
+	return
+}
+
+// FoldRight collapses a sequence from right to left.
+func (s Seq) FoldRight(mapfn func(i int, v0, v float64) float64) (v0 float64) {
+	if s.Len() == 0 {
+		return 0
+	}
+
+	for i := s.Len() - 1; i >= 0; i-- {
+		v0 = mapfn(i, v0, s.GetValue(i))
+	}
+	return
+}
+
+// Sum adds all the elements of a series together.
+func (s Seq) Sum() (accum float64) {
 	if s.Len() == 0 {
 		return 0
 	}
 
-	var accum float64
 	for i := 0; i < s.Len(); i++ {
 		accum += s.GetValue(i)
 	}
-	return accum / float64(s.Len())
+	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 Sequence) Variance() float64 {
+func (s Seq) Variance() float64 {
 	if s.Len() == 0 {
 		return 0
 	}
@@ -60,23 +93,10 @@ func (s Sequence) Variance() float64 {
 }
 
 // StdDev returns the standard deviation.
-func (s Sequence) StdDev() float64 {
+func (s Seq) StdDev() float64 {
 	if s.Len() == 0 {
 		return 0
 	}
 
 	return math.Pow(s.Variance(), 0.5)
 }
-
-// Array is a wrapper for an array of floats that implements `ValuesProvider`.
-type Array []float64
-
-// Len returns the value provider length.
-func (a Array) Len() int {
-	return len(a)
-}
-
-// GetValue returns the value at a given index.
-func (a Array) GetValue(index int) float64 {
-	return a[index]
-}

sequence/sequence_test.go

@@ -1 +1,27 @@
-package util
+package sequence
+
+import (
+	"testing"
+
+	assert "github.com/blendlabs/go-assert"
+)
+
+func TestSequenceEach(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{Array([]float64{1, 2, 3, 4})}
+	values.Each(func(i int, v float64) {
+		assert.Equal(i, v)
+	})
+}
+
+func TestSequenceMap(t *testing.T) {
+	assert := assert.New(t)
+
+	values := Seq{Array([]float64{1, 2, 3, 4})}
+	mapped := values.Map(func(i int, v float64) float64 {
+		assert.Equal(i, v)
+		return v * 2
+	})
+	assert.Equal(4, mapped.Len())
+}

sequence/time.go

@@ -1,4 +1,4 @@
-package util
+package sequence
 
 import (
 	"time"