Backtrader ATR Position Sizing Strategy

import backtrader as bt

class ATRPositionSizing(bt.Strategy):
    params = (('atr_period', 14), ('risk_multiple', 2.0), ('risk_pct', 0.02))

    def __init__(self):
        self.atr = bt.indicators.ATR(self.data, period=self.p.atr_period)

    def next(self):
        if not self.position:
            # Entry signal (simplified)
            if self.data.close[0] > self.data.close[-1]:
                # Position size based on ATR
                stop_distance = self.p.risk_multiple * self.atr[0]
                risk_per_share = stop_distance
                position_size = (self.broker.getvalue() * self.p.risk_pct) / risk_per_share
                self.buy(size=position_size)
                self.stop_price = self.data.close[0] - stop_distance
        else:
            # ATR-based trailing stop
            if self.data.close[0] < self.stop_price:
                self.close()