package indicator import ( "math" "github.com/c9s/bbgo/pkg/types" ) // Refer: Hull Moving Average // Refer URL: https://fidelity.com/learning-center/trading-investing/technical-analysis/technical-indicator-guide/hull-moving-average //go:generate callbackgen -type HULL type HULL struct { types.IntervalWindow ma1 *EWMA ma2 *EWMA result *EWMA UpdateCallbacks []func(value float64) } func (inc *HULL) Update(value float64) { if inc.result == nil { inc.ma1 = &EWMA{IntervalWindow: types.IntervalWindow{inc.Interval, inc.Window / 2}} inc.ma2 = &EWMA{IntervalWindow: types.IntervalWindow{inc.Interval, inc.Window}} inc.result = &EWMA{IntervalWindow: types.IntervalWindow{inc.Interval, int(math.Sqrt(float64(inc.Window)))}} } inc.ma1.Update(value) inc.ma2.Update(value) inc.result.Update(2*inc.ma1.Last() - inc.ma2.Last()) } func (inc *HULL) Last() float64 { if inc.result == nil { return 0 } return inc.result.Last() } func (inc *HULL) Index(i int) float64 { if inc.result == nil { return 0 } return inc.result.Index(i) } func (inc *HULL) Length() int { if inc.result == nil { return 0 } return inc.result.Length() } var _ types.Series = &HULL{} // TODO: should we just ignore the possible overlapping? func (inc *HULL) calculateAndUpdate(allKLines []types.KLine) { doable := false if inc.ma1 == nil || inc.ma1.Length() == 0 { doable = true } for _, k := range allKLines { if !doable && k.StartTime.After(inc.ma1.LastOpenTime) { doable = true } if doable { inc.Update(k.Close.Float64()) inc.EmitUpdate(inc.Last()) } } } func (inc *HULL) handleKLineWindowUpdate(interval types.Interval, window types.KLineWindow) { if inc.Interval != interval { return } inc.calculateAndUpdate(window) } func (inc *HULL) Bind(updater KLineWindowUpdater) { updater.OnKLineWindowUpdate(inc.handleKLineWindowUpdate) }