Merge pull request #824 from c9s/refactor/indicator-api

refactor: indicator: rewrite VWMA calculator

pkg/indicator/inf.go

@@ -6,6 +6,12 @@ type KLineWindowUpdater interface {
 	OnKLineWindowUpdate(func(interval types.Interval, window types.KLineWindow))
 }
 
+type KLineClosedBinder interface {
+	BindK(target KLineClosedEmitter, symbol string, interval types.Interval)
+}
+
+// KLineClosedEmitter is currently applied to the market data stream
+// the market data stream emits the KLine closed event to the listeners.
 type KLineClosedEmitter interface {
 	OnKLineClosed(func(k types.KLine))
 }

pkg/indicator/sma.go

@@ -86,6 +86,10 @@ func (inc *SMA) handleKLineWindowUpdate(interval types.Interval, window types.KL
 	inc.CalculateAndUpdate(window)
 }
 
+func (inc *SMA) BindK(target KLineClosedEmitter, symbol string, interval types.Interval) {
+	target.OnKLineClosed(types.KLineWith(symbol, interval, inc.PushK))
+}
+
 func (inc *SMA) Bind(updater KLineWindowUpdater) {
 	updater.OnKLineWindowUpdate(inc.handleKLineWindowUpdate)
 }

pkg/indicator/vwma.go

@@ -3,8 +3,6 @@ package indicator
 import (
 	"time"
 
-	log "github.com/sirupsen/logrus"
-
 	"github.com/c9s/bbgo/pkg/types"
 )
 
@@ -22,10 +20,14 @@ Volume Weighted Moving Average
 type VWMA struct {
 	types.SeriesBase
 	types.IntervalWindow
+
 	Values         types.Float64Slice
+	PriceVolumeSMA *SMA
+	VolumeSMA      *SMA
+
 	EndTime time.Time
 
-	UpdateCallbacks []func(value float64)
+	updateCallbacks []func(value float64)
 }
 
 func (inc *VWMA) Last() float64 {
@@ -49,46 +51,46 @@ func (inc *VWMA) Length() int {
 
 var _ types.SeriesExtend = &VWMA{}
 
+func (inc *VWMA) Update(price, volume float64) {
+	if inc.PriceVolumeSMA == nil {
+		inc.PriceVolumeSMA = &SMA{IntervalWindow: inc.IntervalWindow}
+		inc.SeriesBase.Series = inc
+	}
+
+	if inc.VolumeSMA == nil {
+		inc.VolumeSMA = &SMA{IntervalWindow: inc.IntervalWindow}
+	}
+
+	inc.PriceVolumeSMA.Update(price * volume)
+	inc.VolumeSMA.Update(volume)
+
+	pv := inc.PriceVolumeSMA.Last()
+	v := inc.VolumeSMA.Last()
+	vwma := pv / v
+	inc.Values.Push(vwma)
+}
 
 func (inc *VWMA) CalculateAndUpdate(allKLines []types.KLine) {
 	if len(allKLines) < inc.Window {
 		return
 	}
 
-	var index = len(allKLines) - 1
+	var last = allKLines[len(allKLines)-1]
-	var kline = allKLines[index]
 
-	if inc.EndTime != zeroTime && kline.EndTime.Before(inc.EndTime) {
+	if inc.VolumeSMA == nil {
+		for _, k := range allKLines {
+			if inc.EndTime != zeroTime && k.EndTime.Before(inc.EndTime) {
 				return
 			}
 
-	var recentK = allKLines[index-(inc.Window-1) : index+1]
+			inc.Update(k.Close.Float64(), k.Volume.Float64())
-
-	pv, err := calculateSMA(recentK, inc.Window, KLinePriceVolumeMapper)
-	if err != nil {
-		log.WithError(err).Error("price x volume SMA error")
-		return
 		}
-	v, err := calculateSMA(recentK, inc.Window, KLineVolumeMapper)
+	} else {
-	if err != nil {
+		inc.Update(last.Close.Float64(), last.Volume.Float64())
-		log.WithError(err).Error("volume SMA error")
-		return
 	}
 
-	if len(inc.Values) == 0 {
+	inc.EndTime = last.EndTime.Time()
-		inc.SeriesBase.Series = inc
+	inc.EmitUpdate(inc.Values.Last())
-	}
-
-	vwma := pv / v
-	inc.Values.Push(vwma)
-
-	if len(inc.Values) > MaxNumOfSMA {
-		inc.Values = inc.Values[MaxNumOfSMATruncateSize-1:]
-	}
-
-	inc.EndTime = allKLines[index].EndTime.Time()
-
-	inc.EmitUpdate(vwma)
 }
 
 func (inc *VWMA) handleKLineWindowUpdate(interval types.Interval, window types.KLineWindow) {

pkg/indicator/vwma_callbacks.go

@@ -5,11 +5,11 @@ package indicator
 import ()
 
 func (inc *VWMA) OnUpdate(cb func(value float64)) {
-	inc.UpdateCallbacks = append(inc.UpdateCallbacks, cb)
+	inc.updateCallbacks = append(inc.updateCallbacks, cb)
 }
 
 func (inc *VWMA) EmitUpdate(value float64) {
-	for _, cb := range inc.UpdateCallbacks {
+	for _, cb := range inc.updateCallbacks {
 		cb(value)
 	}
 }