我在试图运行github上的backtrader示例安装代码时遇到了这个错误。在做了一些研究之后，我发现这个错误可能源于雅虎财务api已经过时或者不再与backtrader软件包兼容。我计划使用在线数据源进行我想做的回溯测试，那么有人知道我如何解决雅虎数据源的问题吗？一些在线消息来源建议深入研究源代码。我已经尝试过那些建议，但没有结果。

from datetime import datetime
import backtrader as bt

class SmaCross(bt.SignalStrategy):
    def __init__(self):
        sma1, sma2 = bt.ind.SMA(period=10), bt.ind.SMA(period=30)
        crossover = bt.ind.CrossOver(sma1, sma2)
        self.signal_add(bt.SIGNAL_LONG, crossover)

cerebro = bt.Cerebro()
cerebro.addstrategy(SmaCross)

data0 = bt.feeds.YahooFinanceData(dataname='AAPL', fromdate=datetime(2011, 1, 1),
                                  todate=datetime(2012, 12, 31))
cerebro.adddata(data0)

cerebro.run()
cerebro.plot()

错误堆栈：

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
<ipython-input-2-4abfaa589128> in <module>
     12 cerebro.adddata(data0)
     13 
---> 14 cerebro.run()
     15 cerebro.plot()

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/cerebro.py in run(self,**kwargs)
   1125             # let's skip process "spawning"
   1126             for iterstrat in iterstrats:
-> 1127                 runstrat = self.runstrategies(iterstrat)
   1128                 self.runstrats.append(runstrat)
   1129                 if self._dooptimize:

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/cerebro.py in runstrategies(self, iterstrat, predata)
   1208                 if self._exactbars < 1:  # datas can be full length
   1209                     data.extend(size=self.params.lookahead)
-> 1210                 data._start()
   1211                 if self._dopreload:
   1212                     data.preload()

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/feed.py in _start(self)
    201 
    202     def _start(self):
--> 203         self.start()
    204 
    205         if not self._started:

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/feeds/yahoo.py in start(self)
    354 
    355         # Prepared a "path" file -  CSV Parser can take over
--> 356         super(YahooFinanceData, self).start()
    357 
    358 

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/feeds/yahoo.py in start(self)
     92 
     93     def start(self):
---> 94         super(YahooFinanceCSVData, self).start()
     95 
     96         if not self.params.reverse:

~/opt/anaconda3/lib/python3.8/site-packages/backtrader/feed.py in start(self)
    672             else:
    673                 # Let an exception propagate to let the caller know
--> 674                 self.f = io.open(self.p.dataname, 'r')
    675 
    676         if self.p.headers:

FileNotFoundError: [Errno 2] No such file or directory: 'AAPL'