Sizer calculating ATR indicator values

[Trade Prophet]

Is there a way for a sizer to hold the ATR calculation without initializing ATR in the strategy init?
For design decoupling purposes I would like the sizer to calculate a specific ticker's ATR value and then compute the position size,the ATR calculation should be the sizer's "head ache",not the strategies init ..
Can a sizer calculate ATR values for data without that ATR been initialized in the strategy?

this does not seem to calculate ATR values :

    # inside the sizer 
    def _getsizing(self, comminfo, cash, data, isbuy):
        atr = bt.indicators.ATR(data, period=self.atr_parameter) # not initialized in __init__,**always empty ...**

        return position_size_that_depends_on_atr  #  crash ..

[backtrader]

The Sizer instance is created inside the Strategy and the indicator will look for such Strategy to register itself. It has to do it or it wouldn't else work.

Bottomline: It will still be as if you had done inside the Strategy

Caveat Emptor: never tried.

[Trade Prophet]

OK,
Thank you for your reply ( and kudos on the incredible work ..)

[aaggmm]

Has this been solved? If so is it possible to post the Sizer code? Thanks!

[Trade Prophet]

class AtrBasedPositionSize(bt.Sizer):
   def __init__(self, atr_parameter, one_bar_risk, atrs):
       self.atr_parameter = atr_parameter
       self.atrs = atrs

   def _getsizing(self, comminfo, cash, data, isbuy):
       if(len(data)<=self.atr_parameter):return 0
       ticker = data._name
       position_size = int((self.broker.getvalue()) / self.atrs[ticker][0])
       return position_size 

[aaggmm]

Thanks !