package indicator import ( "time" "github.com/c9s/bbgo/pkg/types" ) /* vwap implements the volume weighted average price (VWAP) indicator: Volume Weighted Average Price (VWAP) Definition - https://www.investopedia.com/terms/v/vwap.asp Volume-Weighted Average Price (VWAP) Explained - https://academy.binance.com/en/articles/volume-weighted-average-price-vwap-explained */ //go:generate callbackgen -type VWAP type VWAP struct { types.IntervalWindow Values types.Float64Slice WeightedSum float64 VolumeSum float64 EndTime time.Time UpdateCallbacks []func(value float64) } func (inc *VWAP) calculateVWAP(kLines []types.KLine, priceF KLinePriceMapper) (vwap float64) { for i, k := range kLines { inc.update(k, priceF, 1.0) // add kline // if window size is not zero, then we do not apply sliding window method if inc.Window != 0 && len(inc.Values) >= inc.Window { inc.update(kLines[i-inc.Window], priceF, -1.0) // pop kline } vwap = inc.WeightedSum / inc.VolumeSum inc.Values.Push(vwap) } return vwap } func (inc *VWAP) update(kLine types.KLine, priceF KLinePriceMapper, multiplier float64) { // multiplier = 1 or -1 price := priceF(kLine) volume := kLine.Volume inc.WeightedSum += multiplier * price * volume inc.VolumeSum += multiplier * volume } func (inc *VWAP) calculateAndUpdate(kLines []types.KLine) { if len(kLines) < inc.Window { return } var priceF = KLineTypicalPriceMapper var dataLen = len(kLines) // init the values from the kline data var from = 1 if len(inc.Values) == 0 { // for the first value, we should use the close price price := priceF(kLines[0]) volume := kLines[0].Volume inc.Values = []float64{price} inc.WeightedSum = price * volume inc.VolumeSum = volume } else { // update vwap with the existing values for i := dataLen - 1; i > 0; i-- { var k = kLines[i] if k.EndTime.After(inc.EndTime) { from = i } else { break } } } // update vwap for i := from; i < dataLen; i++ { inc.update(kLines[i], priceF, 1.0) // add kline if i >= inc.Window { inc.update(kLines[i-inc.Window], priceF, -1.0) // pop kline } vwap := inc.WeightedSum / inc.VolumeSum inc.Values.Push(vwap) inc.EmitUpdate(vwap) inc.EndTime = kLines[i].EndTime } } func (inc *VWAP) handleKLineWindowUpdate(interval types.Interval, window types.KLineWindow) { if inc.Interval != interval { return } inc.calculateAndUpdate(window) } func (inc *VWAP) Bind(updater KLineWindowUpdater) { updater.OnKLineWindowUpdate(inc.handleKLineWindowUpdate) }