How to write size into self.mystats.write

vaclavku

Hello guys,
anyone can help me? I try to write the size of trade while next().
My understanding is that first define self.tradesize in notify_trade:

def notify_trade(self, trade):
        if trade.justopened:
            self.tradesize = trade.size

Then, I try to calculate the trade in next():

        if self.tradesize:
            self.tsize = self.tradesize[0]
        else:
            self.tsize = 0

I get the error: "AttributeError: 'Lines_LineSeries_LineIterator_DataAccessor_Strateg' object has no attribute 'tradesize'"

What do I do wrong?

Many thanks,
Vaclav

ab_trader

self.tradesize as it is calculated in the notify_trade() is a number. So I don't think that self.tradesize[0] is a valid call. Otherwise I don't see any other issues with the piece of code above. Also it is better to provide full error message since python shows lines of code which causes the error.

vaclavku

Hello, thanks for support. To be honest, I don't want leave the topic without a clue not meet the issue in future.
When I log the self.tradesize in notify_trade, it works well.
However, I understand the issue in the way, the instance of class does not know the (self.)tradesize.

  File "C:\UsersXXX\___master\master.py", line 137, in runstrat
    cebrun = cerebro.run()
  File "C:\UsersXXX\lib\site-packages\backtrader\cerebro.py", line 1127, in run
    runstrat = self.runstrategies(iterstrat)
  File "C:\UsersXXX\lib\site-packages\backtrader\cerebro.py", line 1293, in runstrategies
    self._runonce(runstrats)
  File "C:\UsersXXX\lib\site-packages\backtrader\cerebro.py", line 1695, in _runonce
    strat._oncepost(dt0)
  File "C:\UsersXXX\lib\site-packages\backtrader\strategy.py", line 311, in _oncepost
    self.nextstart()  # only called for the 1st value
  File "C:\UsersXXX\lib\site-packages\backtrader\lineiterator.py", line 347, in nextstart
    self.next()
  File "C:\UsersXXX\___master\modules\strategy.py", line 149, in next
    if self.tradesize:
  File "C:\UsersXXX\lib\site-packages\backtrader\lineseries.py", line 461, in __getattr__
    return getattr(self.lines, name)
AttributeError: 'Lines_LineSeries_LineIterator_DataAccessor_Strateg' object has no attribute 'tradesize'

Please, note: I try it without the index as well.

        if self.tradesize:
            self.tsize = self.tradesize
        else:
            self.tsize = 0

Line 149 refers to the condition...
Thank you for your time.

vaclavku

@ab_trader : I've also tried make it in init

self.tsize = bt.If(self.tradesize, self.tradesize, 0)

The issue is almost the same.

This however works well:

    def notify_trade(self, trade):
        if trade.justopened:
            print('----TRADE OPENED----')
            self.tradesize = trade.size
            print(self.tradesize)

And prints the size...

ab_trader

Put self.tradesize = None or self.tradesize = 0 in the __init()__. It is undefined for first next() calls before you get your trade open.

vaclavku

@ab_trader : Many thanks. A new added value for me. Very appreciated.