How to extract trade buying price?

[Chunger-Lo]

Hi, I am a rookie to quantitative trades,

I really love the backtest output of this framework,
and I just want to modify the tutorial example:

Instead of comparing long and short sma signal,
my buying criteria is : current_price > ema
my selling criteria is : current_price < buy_price * 0.9
so I am wondering how to extract the buy_price (the price when I bought) from the trade?
and how to use it as a selling criteria

Sorry for the dumb question, please let me if there's any misunderstanding.
Thank you!

from backtesting import Backtest, Strategy
from backtesting.lib import crossover
from backtesting.test import SMA, GOOG
import pandas as pd
import talib

def EMA(arr: pd.Series, n: int) -> pd.Series:
    res = talib.EMA(pd.Series(arr), timeperiod = n)
    return res

class myCross(Strategy):
    ema_n = 144
    def init(self):
        price = self.data.Close
        self.ema = self.I(EMA, price, self.ema_n)
    
    def next(self):
        if crossover(self.data.Close, self.ema):
            self.buy()
        elif crossover(self.ema, self.trades[-1]['entry_price'] * 0.9):
            self.sell()
            
bt = Backtest(data = GOOG, strategy = myCross, commission=.002,
              exclusive_orders=True)
stats = bt.run()
bt.plot()

[kernc]

Did you see Strategy.trades and Trade.entry_price.

Something like:

        for trade in self.trades:
            if self.data.Close < trade.entry_price * .9:
                trade.close()

[Chunger-Lo]

It worked! thanks for your help.