124 lines
3.1 KiB
Go
124 lines
3.1 KiB
Go
package indicator
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import (
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"time"
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"git.qtrade.icu/lychiyu/qbtrade/pkg/datatype/floats"
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"git.qtrade.icu/lychiyu/qbtrade/pkg/types"
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)
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const MaxNumOfRMA = 1000
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const MaxNumOfRMATruncateSize = 500
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// Running Moving Average
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// Refer: https://github.com/twopirllc/pandas-ta/blob/main/pandas_ta/overlap/rma.py#L5
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// Refer: https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.ewm.html#pandas-dataframe-ewm
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//
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// The Running Moving Average (RMA) is a technical analysis indicator that is used to smooth price data and reduce the lag associated
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// with traditional moving averages. It is calculated by taking the weighted moving average of the input data, with the weighting factors
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// determined by the length of the moving average. The resulting average is then plotted on the price chart as a line, which can be used to
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// make predictions about future price movements. The RMA is typically more responsive to changes in the underlying data than a simple
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// moving average, but may be less reliable in trending markets. It is often used in conjunction with other technical analysis indicators
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// to confirm signals or provide additional information about the security's price.
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//go:generate callbackgen -type RMA
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type RMA struct {
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types.SeriesBase
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types.IntervalWindow
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Values floats.Slice
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EndTime time.Time
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counter int
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Adjust bool
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tmp float64
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sum float64
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updateCallbacks []func(value float64)
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}
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func (inc *RMA) Clone() types.UpdatableSeriesExtend {
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out := &RMA{
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IntervalWindow: inc.IntervalWindow,
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Values: inc.Values[:],
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counter: inc.counter,
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Adjust: inc.Adjust,
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tmp: inc.tmp,
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sum: inc.sum,
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EndTime: inc.EndTime,
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}
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out.SeriesBase.Series = out
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return out
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}
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func (inc *RMA) Update(x float64) {
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lambda := 1 / float64(inc.Window)
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if inc.counter == 0 {
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inc.SeriesBase.Series = inc
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inc.sum = 1
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inc.tmp = x
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} else {
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if inc.Adjust {
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inc.sum = inc.sum*(1-lambda) + 1
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inc.tmp = inc.tmp + (x-inc.tmp)/inc.sum
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} else {
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inc.tmp = inc.tmp*(1-lambda) + x*lambda
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}
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}
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inc.counter++
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inc.Values.Push(inc.tmp)
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if len(inc.Values) > MaxNumOfRMA {
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inc.Values = inc.Values[MaxNumOfRMATruncateSize-1:]
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}
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}
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func (inc *RMA) Last(i int) float64 {
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return inc.Values.Last(i)
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}
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func (inc *RMA) Index(i int) float64 {
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return inc.Last(i)
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}
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func (inc *RMA) Length() int {
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return len(inc.Values)
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}
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var _ types.SeriesExtend = &RMA{}
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func (inc *RMA) PushK(k types.KLine) {
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inc.Update(k.Close.Float64())
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inc.EndTime = k.EndTime.Time()
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}
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func (inc *RMA) CalculateAndUpdate(kLines []types.KLine) {
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last := kLines[len(kLines)-1]
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if len(inc.Values) == 0 {
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for _, k := range kLines {
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if inc.EndTime != zeroTime && !k.EndTime.After(inc.EndTime) {
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continue
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}
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inc.PushK(k)
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}
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} else {
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inc.PushK(last)
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}
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inc.EmitUpdate(inc.Last(0))
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}
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func (inc *RMA) handleKLineWindowUpdate(interval types.Interval, window types.KLineWindow) {
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if inc.Interval != interval {
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return
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}
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inc.CalculateAndUpdate(window)
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}
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func (inc *RMA) Bind(updater KLineWindowUpdater) {
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updater.OnKLineWindowUpdate(inc.handleKLineWindowUpdate)
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}
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