Loading one data series and run cerebro.run(runonce=False) Got Error Message

chaT123

The below code has error message below when I load only one series of OHLC data (In Pandas DataFrame format). But it doesnt have problem when I add a second series of data. i.e with two data series it works.

And when I use "runonce=True" setting, it works also.

So it ONLY doesn't work when I load only one series of data and use "runonce=False" set up. Does anyone know what is wrong here?

"C:\ProgramData\Anaconda3\lib\site-packages\backtrader\linebuffer.py", line 163, in getitem
return self.array[self.idx + ago]
IndexError: array index out of range

class TestStrategy(bt.Strategy):
     def __init__(self):

        self.closePx = self.datas[0].close
       
        

    def next(self):

       # The LINE BELOW POP UP ERROR MSG ABOVE
        print(self.stats.broker.value[0])
       
        # ***************************************************************

    def stop(self):
        pass

data = bt.feeds.PandasData(dataname=dailyOHLCDF, open='Open', high='High', low='Low', close = 'Close', volume = 'Volume'\
, openinterest=None)


cerebro = bt.Cerebro(stdstats=False)

cerebro.adddata(data)
cerebro.addobserver(bt.observers.Broker, plot = False)
cerebro.broker.setcash(500000.0)
cerebro.addstrategy(TestStrategy)
thestrats = cerebro.run(runonce=False)

chaT123

I juse tested self.broker.getvalue() is working.

But self.stats.broker.value[0] not working. So I can just use self.broker.getvalue() right? My goal is to print out broker value every day.

backtrader

An Observer operates after things have happened, because it is observing the overall consequences of your actions and the calculations of indicators.

In iterations next + 1, accessing stats.broker.value[0] will give you the broker value of the previous iteration.

In next + 0 (the 1st time), there is still no data there if you have no indicators forcing you to have a minimum period. And if you have them, you will get and old value as pointed out above.