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Bollinger Bands

Usage​

// Basic usage (20, 2.0 is standard)
bb := s.k.Indicators().BollingerBands(btc, 20, 2.0)

s.k.Log().Debug("Bollinger Bands", btc.Symbol(), "Upper: %s, Middle: %s, Lower: %s",
    bb.Upper, bb.Middle, bb.Lower)

// With options
bb := s.k.Indicators().BollingerBands(btc, 20, 2.0, indicators.IndicatorOptions{
    Interval: "1h",
})

In a Strategy​

func (s *Strategy) GetSignals() ([]*strategy.Signal, error) {
    btc := s.k.Asset("BTC")
    
    price := s.k.Market().Price(btc)
    bb := s.k.Indicators().BollingerBands(btc, 20, 2.0)
    
    // Buy when price touches lower band
    if price.LessThan(bb.Lower) {
        return []*strategy.Signal{
            s.Signal().
                Buy(btc).
                Quantity(decimal.NewFromFloat(0.1)).
                Reason("Price below lower Bollinger Band").
                Build(),
        }, nil
    }
    
    // Sell when price touches upper band
    if price.GreaterThan(bb.Upper) {
        return []*strategy.Signal{
            s.Signal().
                Sell(btc).
                Quantity(decimal.NewFromFloat(0.1)).
                Reason("Price above upper Bollinger Band").
                Build(),
        }, nil
    }
    
    return nil, nil
}

Parameters​

BollingerBands(asset, period, stdDev, ...options) *BollingerBandsResult
ParameterTypeDescription
assettypes.AssetAsset to calculate for
periodintSMA period (typically 20)
stdDevfloat64Std dev multiplier (typically 2.0)
options...IndicatorOptionsOptional exchange/interval

Return Value​

type BollingerBandsResult struct {
    Upper  decimal.Decimal  // Upper band (SMA + stdDev)
    Middle decimal.Decimal  // Middle band (SMA)
    Lower  decimal.Decimal  // Lower band (SMA - stdDev)
}

Common Patterns​

Mean Reversion​

price := s.k.Market().Price(btc)
bb := s.k.Indicators().BollingerBands(btc, 20, 2.0)

// Buy at lower band
if price.LessThan(bb.Lower) {
    return s.Signal().Buy(btc).Build()
}

// Sell at upper band
if price.GreaterThan(bb.Upper) {
    return s.Signal().Sell(btc).Build()
}

Breakout Detection​

bb := s.k.Indicators().BollingerBands(btc, 20, 2.0)

// Band width (volatility measure)
bandWidth := bb.Upper.Sub(bb.Lower).Div(bb.Middle).Mul(decimal.NewFromInt(100))

// Squeeze: bands narrowing (low volatility)
if bandWidth.LessThan(decimal.NewFromInt(10)) {
    // Potential breakout coming
}

What It Measures​

Bollinger Bands measure volatility and identify overbought/oversold conditions:

Formulas​

Middle Band = SMA(period)
Upper Band = Middle + (stdDev × Standard Deviation)
Lower Band = Middle - (stdDev × Standard Deviation)

Interpretation​

  • Price near upper band: Overbought
  • Price near lower band: Oversold
  • Bands narrow: Low volatility, potential breakout
  • Bands wide: High volatility

See Also​

References​