execution price for market order

PythonNoob

I have gone through the documentation and it mentioned when order type is "market" then the executed price should be the open of next period but i dont understand how it ends up with below
e.g. there is an order 2021-01-12, BUY CREATE but ends up the executed price is 128.57 , which is not the open of 2021-01-13. (which yahoo it should be 128.75999450683594)

and sorry for the second question I saw being asked many times yet I dont see any clear explanation. is there anyway i can run python line by line like F8 in excel VBA? i know there is a debug function (ALT SHIFT E) but when i try to run the line one line it ends up error on lines like defining a class

Main

import numpy as np
import pandas as pd
import datetime
import time
import yfinance as yf
import backtrader as bt
from Strategies import TestStrategy

df1 = yf.download("AAPL",start='2021-01-03',end='2021-02-05')
print(df1)

df1.to_csv("YahooFileAAPL.csv")
data = bt.feeds.YahooFinanceCSVData(dataname='YahooFileAAPL.csv')

cerebro = bt.Cerebro()
cerebro.broker.set_cash(500000)
cerebro.adddata(data)
cerebro.addstrategy(TestStrategy)

print('Starting Portfolio Value: %d' % cerebro.broker.getvalue())
cerebro.run()
print('Final Portfolio Value: %d' % cerebro.broker.getvalue())

Create a Stratey

class TestStrategy(bt.Strategy):

def log(self, txt, dt=None):
    ''' Logging function for this strategy'''
    dt = dt or self.datas[0].datetime.date(0)
    print('%s, %s' % (dt.isoformat(), txt))

def __init__(self):
    # Keep a reference to the "close" line in the data[0] dataseries
    self.dataclose = self.datas[0].close
    self.order = None

def notify_order(self, order):
    if order.status in [order.Submitted, order.Accepted]:
        return

    if order.status in [order.Completed]:

        if order.isbuy():
            self.log(
                'BUY EXECUTED, Price: %.2f, Cost: %.2f, Comm %.2f' %
                (order.executed.price,
                 order.executed.value,
                 order.executed.comm))

        elif order.issell():
            self.log("SELL EXECTUED{}".format(order.executed.price))

        self.bar_executed = len(self)

    self.order = None


def next(self):
    # Simply log the closing price of the series from the reference
    self.log('Close, %.2f' % self.dataclose[0])
    # print(str(len(self)) +" "+ str(bool(self.position)))
    # print(type(self.position))


    # print(len(self))
    # print(self.order)
    # print(self.position)
    if self.order:
        return

    if not self.position:
        if self.dataclose[0] < self.dataclose[-1]:
            # current close less than previous close

            if self.dataclose[-1] < self.dataclose[-2]:
                # previous close less than the previous close

                # BUY, BUY, BUY!!! (with all possible default parameters)
                self.log('BUY CREATE, %.2f' % self.dataclose[0])
                self.order = self.buy()
    else:
        if len(self) >= (self.bar_executed + 5):
            self.log("SELL CREATED {}".format(self.dataclose[0]))
            self.order = self.sell()

rajanprabu

@pythonnoob

You are reading from Yahoo finance which has a field Adj. Price this is used to adjust the open, high , low, close prices. Thats why you are seeing different price.