Multi-timeframe position size

[zetra_trader]

Hi All,

I'm working on a multi-timeframe data example and I'm getting unexpected results for the position size. I set the buy size to the same fixed value for all timeframes. My expectation is that for each timeframe only the given size would be bought. However, this is not the case. I get different positions for each timeframe. Please see code and output below. Can someone please explain to me what I'm missing. Thanks.

Code:

import backtrader as bt
        
class MyStrategy(bt.Strategy):
        def log(self, txt, dt=None, tm=None):
            ''' Logging function fot this strategy'''
            dt = dt or self.datas[0].datetime.date(0)
            tm = tm or self.datas[0].datetime.time(0)
            print('%s %s, %s' % (dt.isoformat(), tm.isoformat(), txt))
    
    
        def __init__(self):
            
            

            self.all_ind = {}
            
            for i,d in enumerate(self.datas):
                self.all_ind[i] = bt.talib.EMA(self.datas[i], period=10)    
            
                        
        def next(self):
             for i, d in enumerate(self.datas):
                  pos    = self.getposition(d).size
                  print("Position {} {}".format(pos,d._name))
                  if not pos:
                       if self.getdatabyname(d._name).close[0] > self.all_ind[i][0] :
                           self.o = self.buy(data=d,size=10)
                           
                        
                 
if __name__ == '__main__':
    
    
    cerebro = bt.Cerebro()

    data0 = bt.feeds.GenericCSVData(timeframe=bt.TimeFrame.Minutes,dataname=".../DAT_ASCII_USDJPY_M1_2001.csv",                                  separator=';',
                                  nullvalue=float('NaN'),
                                  dtformat=('%Y%m%d %H%M%S'),
                                  tmformat=('%H%M%S'),
                                  datetime=0,
                                  time=-1,
                                  open=1,
                                  high=2,
                                  low=3,
                                  close=4,
                                  volume=-1,
                                  openinterest=-1,
                                  compression=1)
    
    cerebro.adddata(data0, name="data0")
    cerebro.resampledata(data0,name="data1", timeframe=bt.TimeFrame.Minutes,compression=15)    
    cerebro.resampledata(data0,name="data2", timeframe=bt.TimeFrame.Minutes,compression=30)    

    startcash = 10000
     
     # Set our desired cash start
    cerebro.broker.setcash(startcash)

     # Set the strategy
    cerebro.addstrategy(MyStrategy)

Now the output:

Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2
Position 10 data0
Position 30 data1
Position 40 data2