I found this helpful
https://backtest-rookies.com/2020/05/09/backtrader-portfolio-rebalancing-with-alpha-vantage/
Thanks
SJ

@ab_trader Yes, Thank you!!

@run-out Thank you!!! understood the mistake at my end and got it now. I highly appreciate your on-time help. Many thanks again.
-SJ

@run-out Thank you! I see you have responded on a similar issue on another thread. Let me check that our and only if needed, will open an issue.
Thanks
SJ

@ab_trader
Hello, I too facing the timer issue, it doesn't trigger not only for this simple buy and hold but anywhere I tried. The pandas feed I am using has datetime index, I also tried tz_localize('UTC')

prices.index = prices.index.tz_localize('UTC')
prices.info()
DatetimeIndex: 2792 entries, 2009-01-02 00:00:00+00:00 to 2020-05-19 00:00:00+00:00
Data columns (total 5 columns):
 #   Column  Non-Null Count  Dtype  
---  ------  --------------  -----  
 0   open    2792 non-null   float64
 1   high    2792 non-null   float64
 2   low     2792 non-null   float64
 3   close   2792 non-null   float64
 4   volume  2792 non-null   float64

prices.head()
	open	high	low	close	volume
date					
2009-01-02 00:00:00+00:00	145.625000	145.625000	140.475006	50.516472	9012080.0
2009-01-05 00:00:00+00:00	142.500000	148.087006	142.462006	52.332775	11241232.0
2009-01-06 00:00:00+00:00	147.500000	148.750000	143.169006	52.143211	11563864.0
2009-01-07 00:00:00+00:00	146.393997	149.694000	143.199997	52.991051	22538352.0
2009-01-09 00:00:00+00:00	148.261993	158.324997	146.250000	53.698215	40182160.0

I appreciate any help!!

@Ronny-Li said in ZeroDivisionError: float division by zero:

inv = [bt.DivByZero(bt.LineNum(1), v) for v in vs]

Hello Ronny, Thanks a ton!! it worked.
If I may share another issue faced by me is monthly rebalancing. The workaround I do to resample data for monthly frequency and run the backtest. I tried below code to trigger monthly rebalancing on daily price series however looking at the log I understand it's not working. Appreciate help/ pointers

class Strategy(bt.Strategy):
    params = dict(
        selcperc=0.15,  # percentage of stocks to select from the universe
        rperiod=1,  # period for the returns calculation, default 1 period
        vperiod=126,  # lookback period for volatility - default 36 periods
        mperiod=126,  # lookback period for momentum - default 12 periods
        reserve=0.05,  # 5% reserve capital
        when=bt.timer.SESSION_END, #SESSION_START,
        timer=True,
        monthdays=[1],
        monthcarry=True
    )
    
    def log(self, arg):
            print('{} {}'.format(self.datetime.date(), arg))   

    def __init__(self):
        
#         bt.indicators.Stochastic(self.datas[0], safediv=True)
        
        # calculate 1st the amount of stocks that will be selected
        self.selnum = int(len(self.datas) * self.p.selcperc)

        # allocation perc per stock
        # reserve kept to make sure orders are not rejected due to
        # margin. Prices are calculated when known (close), but orders can only
        # be executed next day (opening price). Price can gap upwards
        self.perctarget = (1.0 - self.p.reserve) / self.selnum

        # returns, volatilities and momentums
        rs = [bt.ind.PctChange(d, period=self.p.rperiod) for d in self.datas] # safediv safezero
        vs = [bt.ind.StdDev(ret, period=self.p.vperiod) for ret in rs]
        ms = [bt.ind.ROC(d, period=self.p.mperiod) for d in self.datas]

        # simple rank formula: (momentum * net payout) / volatility
        # the highest ranked: low vol, large momentum, large payout
#         self.ranks = {d: d.npy * m / v for d, v, m in zip(self.datas, vs, ms)}
        self.ranks = {d: m / v for d, v, m in zip(self.datas, vs, ms)}

#         self.add_timer(
#             when=self.p.when,
#             monthdays=self.p.monthdays,
#             monthcarry=self.p.monthcarry
#         )

        # Add a timer which will be called on the 1st trading day of the month
        self.add_timer(
            bt.timer.SESSION_END,  # when it will be called
            monthdays=[1],  # called on the 1st day of the month
            monthcarry=self.p.monthcarry,  # called on the 2nd day if the 1st is holiday
        )

    def notify_timer(self, timer, when, *args, **kwargs):
        if self._getminperstatus() < 0:
            self.rebalance()

    def rebalance(self):
        # sort data and current rank
        ranks = sorted(
            self.ranks.items(),  # get the (d, rank), pair
            key=lambda x: x[1][0],  # use rank (elem 1) and current time "0"
            reverse=True,  # highest ranked 1st ... please
        )

        # put top ranked in dict with data as key to test for presence
        rtop = dict(ranks[:self.selnum])


        # For logging purposes of stocks leaving the portfolio
        rbot = dict(ranks[self.selnum:])

        # prepare quick lookup list of stocks currently holding a position
        posdata = [d for d, pos in self.getpositions().items() if pos]

        # remove those no longer top ranked
        # do this first to issue sell orders and free cash
        for d in (d for d in posdata if d not in rtop):
            self.log('Leave {} - Rank {:.2f}'.format(d._name, rbot[d][0]))
            self.order_target_percent(d, target=0.0)

        # rebalance those already top ranked and still there
        for d in (d for d in posdata if d in rtop):
            self.log('Rebal {} - Rank {:.2f}'.format(d._name, rtop[d][0]))
            self.order_target_percent(d, target=self.perctarget)
            del rtop[d]  # remove it, to simplify next iteration

        # issue a target order for the newly top ranked stocks
        # do this last, as this will generate buy orders consuming cash
        for d in rtop:
            self.log('Enter {} - Rank {:.2f}'.format(d._name, rtop[d][0]))
            self.order_target_percent(d, target=self.perctarget) 
            
    def next(self):
        self.notify_timer(self, self.p.timer, self.p.when)

Execution Log:

Starting Portfolio Value: 100000.00
2014-07-07 Enter CONCOR.NS - Rank 46.67
2014-07-07 Enter AUROPHARMA.NS - Rank 43.93
2014-07-07 Enter SHREECEM.NS - Rank 42.47
2014-07-07 Enter LT.NS - Rank 38.76
2014-07-07 Enter PFC.NS - Rank 36.94
2014-07-07 Enter SBIN.NS - Rank 36.59
2014-07-07 Enter ASHOKLEY.NS - Rank 35.69
2014-07-07 Enter MOTHERSUMI.NS - Rank 34.47
2014-07-07 Enter EICHERMOT.NS - Rank 34.41
2014-07-07 Enter PNB.NS - Rank 34.04
2014-07-07 Enter PGHH.NS - Rank 33.73
2014-07-07 Enter TITAN.NS - Rank 32.30
2014-07-07 Enter BPCL.NS - Rank 31.73
2014-07-08 Leave ASHOKLEY.NS - Rank 28.06
2014-07-08 Leave TITAN.NS - Rank 27.23
2014-07-08 Rebal AUROPHARMA.NS - Rank 35.99
2014-07-08 Rebal BPCL.NS - Rank 31.08
2014-07-08 Rebal CONCOR.NS - Rank 38.02
2014-07-08 Rebal LT.NS - Rank 36.04
2014-07-08 Rebal MOTHERSUMI.NS - Rank 30.61
2014-07-08 Rebal PFC.NS - Rank 31.57
2014-07-08 Rebal PGHH.NS - Rank 32.45
2014-07-08 Rebal PNB.NS - Rank 30.18
2014-07-08 Rebal SBIN.NS - Rank 33.78
2014-07-08 Rebal SHREECEM.NS - Rank 40.49
2014-07-08 Enter EICHERMOT.NS - Rank 33.64
2014-07-08 Enter BAJAJHLDNG.NS - Rank 32.01
2014-07-08 Enter AXISBANK.NS - Rank 30.54
2014-07-09 Leave AUROPHARMA.NS - Rank 26.37
2014-07-09 Rebal AXISBANK.NS - Rank 30.17
2014-07-09 Rebal BAJAJHLDNG.NS - Rank 29.87
2014-07-09 Rebal BPCL.NS - Rank 32.39
2014-07-09 Rebal CONCOR.NS - Rank 37.63
2014-07-09 Rebal LT.NS - Rank 34.93
2014-07-09 Rebal MOTHERSUMI.NS - Rank 29.34
2014-07-09 Rebal PFC.NS - Rank 30.32
2014-07-09 Rebal PGHH.NS - Rank 30.47
2014-07-09 Rebal PNB.NS - Rank 30.50
2014-07-09 Rebal SBIN.NS - Rank 35.63
2014-07-09 Rebal SHREECEM.NS - Rank 38.99
2014-07-09 Enter EICHERMOT.NS - Rank 31.73
2014-07-09 Enter ICICIBANK.NS - Rank 28.64
2014-07-10 Leave BAJAJHLDNG.NS - Rank 29.43
2014-07-10 Leave ICICIBANK.NS - Rank 27.20
2014-07-10 Rebal AXISBANK.NS - Rank 31.25
2014-07-10 Rebal BPCL.NS - Rank 33.67
2014-07-10 Rebal CONCOR.NS - Rank 40.36
2014-07-10 Rebal LT.NS - Rank 34.31
2014-07-10 Rebal MOTHERSUMI.NS - Rank 33.70
2014-07-10 Rebal PFC.NS - Rank 34.81
2014-07-10 Rebal PGHH.NS - Rank 29.82
2014-07-10 Rebal PNB.NS - Rank 30.65
2014-07-10 Rebal SBIN.NS - Rank 35.79
2014-07-10 Rebal SHREECEM.NS - Rank 39.86
2014-07-10 Enter EICHERMOT.NS - Rank 30.94
2014-07-10 Enter PAGEIND.NS - Rank 30.30
2014-07-10 Enter ADANIPORTS.NS - Rank 29.64
2014-07-11 Leave ADANIPORTS.NS - Rank 21.94
2014-07-11 Leave PFC.NS - Rank 26.35
2014-07-11 Leave PNB.NS - Rank 26.56
2014-07-11 Rebal AXISBANK.NS - Rank 30.62
2014-07-11 Rebal BPCL.NS - Rank 32.29
2014-07-11 Rebal CONCOR.NS - Rank 34.57
2014-07-11 Rebal LT.NS - Rank 30.98
2014-07-11 Rebal MOTHERSUMI.NS - Rank 30.25
2014-07-11 Rebal PGHH.NS - Rank 28.42
2014-07-11 Rebal SBIN.NS - Rank 31.46
2014-07-11 Rebal SHREECEM.NS - Rank 37.59
2014-07-11 Enter EICHERMOT.NS - Rank 30.97
2014-07-11 Enter PAGEIND.NS - Rank 28.64
2014-07-11 Enter IOC.NS - Rank 28.58
2014-07-11 Enter AUROPHARMA.NS - Rank 28.29
2014-07-11 Enter HINDPETRO.NS - Rank 27.17
2014-07-14 Leave IOC.NS - Rank 26.02
2014-07-14 Leave MOTHERSUMI.NS - Rank 26.31
2014-07-14 Rebal AUROPHARMA.NS - Rank 30.59
2014-07-14 Rebal AXISBANK.NS - Rank 34.12
2014-07-14 Rebal BPCL.NS - Rank 31.61
2014-07-14 Rebal CONCOR.NS - Rank 34.03
2014-07-14 Rebal HINDPETRO.NS - Rank 27.88
2014-07-14 Rebal LT.NS - Rank 34.89
2014-07-14 Rebal PGHH.NS - Rank 28.22
2014-07-14 Rebal SBIN.NS - Rank 31.84
2014-07-14 Rebal SHREECEM.NS - Rank 38.14
2014-07-14 Enter EICHERMOT.NS - Rank 31.50
2014-07-14 Enter PFC.NS - Rank 29.32
2014-07-14 Enter PNB.NS - Rank 28.90
2014-07-14 Enter HAVELLS.NS - Rank 27.97
2014-07-15 Leave HAVELLS.NS - Rank 29.65
2014-07-15 Rebal AUROPHARMA.NS - Rank 34.18
2014-07-15 Rebal AXISBANK.NS - Rank 38.14
2014-07-15 Rebal BPCL.NS - Rank 32.98
2014-07-15 Rebal CONCOR.NS - Rank 36.38
2014-07-15 Rebal HINDPETRO.NS - Rank 29.95
2014-07-15 Rebal LT.NS - Rank 38.46
2014-07-15 Rebal PFC.NS - Rank 32.38
2014-07-15 Rebal PGHH.NS - Rank 30.71
2014-07-15 Rebal PNB.NS - Rank 31.95
2014-07-15 Rebal SBIN.NS - Rank 36.52
2014-07-15 Rebal SHREECEM.NS - Rank 37.98
2014-07-15 Enter EICHERMOT.NS - Rank 34.44
2014-07-15 Enter MOTHERSUMI.NS - Rank 30.71
2014-07-16 Leave PFC.NS - Rank 28.23
2014-07-16 Rebal AUROPHARMA.NS - Rank 37.10
2014-07-16 Rebal AXISBANK.NS - Rank 39.30
2014-07-16 Rebal BPCL.NS - Rank 32.91
2014-07-16 Rebal CONCOR.NS - Rank 38.53
2014-07-16 Rebal HINDPETRO.NS - Rank 30.86
2014-07-16 Rebal LT.NS - Rank 37.69
2014-07-16 Rebal MOTHERSUMI.NS - Rank 35.12
2014-07-16 Rebal PGHH.NS - Rank 31.92
2014-07-16 Rebal PNB.NS - Rank 31.67
2014-07-16 Rebal SBIN.NS - Rank 36.63
2014-07-16 Rebal SHREECEM.NS - Rank 38.88
2014-07-16 Enter EICHERMOT.NS - Rank 33.98
2014-07-16 Enter ADANIPORTS.NS - Rank 31.71
2014-07-17 Leave ADANIPORTS.NS - Rank 31.33
2014-07-17 Leave PGHH.NS - Rank 28.79
2014-07-17 Rebal AUROPHARMA.NS - Rank 36.68
2014-07-17 Rebal AXISBANK.NS - Rank 39.47
2014-07-17 Rebal BPCL.NS - Rank 33.75
2014-07-17 Rebal CONCOR.NS - Rank 40.51
2014-07-17 Rebal HINDPETRO.NS - Rank 31.85
2014-07-17 Rebal LT.NS - Rank 39.13
2014-07-17 Rebal MOTHERSUMI.NS - Rank 35.79
2014-07-17 Rebal PNB.NS - Rank 32.22
2014-07-17 Rebal SBIN.NS - Rank 38.27
2014-07-17 Rebal SHREECEM.NS - Rank 39.25
2014-07-17 Enter EICHERMOT.NS - Rank 36.00
2014-07-17 Enter HAVELLS.NS - Rank 34.63
2014-07-17 Enter ULTRACEMCO.NS - Rank 32.15
2014-07-18 Leave HINDPETRO.NS - Rank 28.44
2014-07-18 Leave PNB.NS - Rank 29.86
2014-07-18 Leave ULTRACEMCO.NS - Rank 27.88
2014-07-18 Rebal AUROPHARMA.NS - Rank 37.18
2014-07-18 Rebal AXISBANK.NS - Rank 41.21
2014-07-18 Rebal BPCL.NS - Rank 32.85
2014-07-18 Rebal CONCOR.NS - Rank 40.39
2014-07-18 Rebal HAVELLS.NS - Rank 36.26
2014-07-18 Rebal LT.NS - Rank 37.78
2014-07-18 Rebal MOTHERSUMI.NS - Rank 35.56
2014-07-18 Rebal SBIN.NS - Rank 36.24
2014-07-18 Rebal SHREECEM.NS - Rank 38.80
2014-07-18 Enter EICHERMOT.NS - Rank 36.03
2014-07-18 Enter ICICIBANK.NS - Rank 30.90
2014-07-18 Enter ASHOKLEY.NS - Rank 30.70
2014-07-18 Enter ADANIPORTS.NS - Rank 30.63
2014-07-21 Leave ASHOKLEY.NS - Rank 29.98
2014-07-21 Rebal ADANIPORTS.NS - Rank 30.28
2014-07-21 Rebal AUROPHARMA.NS - Rank 33.30
2014-07-21 Rebal AXISBANK.NS - Rank 42.66
2014-07-21 Rebal BPCL.NS - Rank 31.95
2014-07-21 Rebal CONCOR.NS - Rank 40.64
2014-07-21 Rebal HAVELLS.NS - Rank 33.77
2014-07-21 Rebal ICICIBANK.NS - Rank 30.98
2014-07-21 Rebal LT.NS - Rank 36.36
2014-07-21 Rebal MOTHERSUMI.NS - Rank 34.23
2014-07-21 Rebal SBIN.NS - Rank 35.12
2014-07-21 Rebal SHREECEM.NS - Rank 40.04
2014-07-21 Enter EICHERMOT.NS - Rank 35.67
2014-07-21 Enter PAGEIND.NS - Rank 30.67
2014-07-22 Leave ADANIPORTS.NS - Rank 30.48
2014-07-22 Leave BPCL.NS - Rank 30.13
2014-07-22 Rebal AUROPHARMA.NS - Rank 35.39
2014-07-22 Rebal AXISBANK.NS - Rank 44.50
2014-07-22 Rebal CONCOR.NS - Rank 44.00
2014-07-22 Rebal HAVELLS.NS - Rank 34.87
2014-07-22 Rebal ICICIBANK.NS - Rank 33.02
2014-07-22 Rebal LT.NS - Rank 35.56
2014-07-22 Rebal MOTHERSUMI.NS - Rank 34.47
2014-07-22 Rebal SBIN.NS - Rank 35.92
2014-07-22 Rebal SHREECEM.NS - Rank 37.68
2014-07-22 Enter EICHERMOT.NS - Rank 35.59
2014-07-22 Enter PNB.NS - Rank 31.50
2014-07-22 Enter PFC.NS - Rank 30.66
2014-07-22 Enter ASHOKLEY.NS - Rank 30.55
2014-07-23 Leave PFC.NS - Rank 30.53
2014-07-23 Rebal ASHOKLEY.NS - Rank 31.39
2014-07-23 Rebal AUROPHARMA.NS - Rank 31.51
2014-07-23 Rebal AXISBANK.NS - Rank 42.79
2014-07-23 Rebal CONCOR.NS - Rank 41.76
2014-07-23 Rebal HAVELLS.NS - Rank 31.93
2014-07-23 Rebal ICICIBANK.NS - Rank 33.48
2014-07-23 Rebal LT.NS - Rank 35.85
2014-07-23 Rebal MOTHERSUMI.NS - Rank 30.82
2014-07-23 Rebal PNB.NS - Rank 31.00
2014-07-23 Rebal SBIN.NS - Rank 35.45
2014-07-23 Rebal SHREECEM.NS - Rank 37.84
2014-07-23 Enter EICHERMOT.NS - Rank 33.90
2014-07-23 Enter BPCL.NS - Rank 31.62
2014-07-24 Leave AUROPHARMA.NS - Rank 28.30
2014-07-24 Rebal ASHOKLEY.NS - Rank 32.42
2014-07-24 Rebal AXISBANK.NS - Rank 40.71
2014-07-24 Rebal BPCL.NS - Rank 33.21
2014-07-24 Rebal CONCOR.NS - Rank 42.58
2014-07-24 Rebal HAVELLS.NS - Rank 32.82
2014-07-24 Rebal ICICIBANK.NS - Rank 31.19
2014-07-24 Rebal LT.NS - Rank 35.29
2014-07-24 Rebal MOTHERSUMI.NS - Rank 30.00
2014-07-24 Rebal PNB.NS - Rank 30.52
2014-07-24 Rebal SBIN.NS - Rank 35.13
2014-07-24 Rebal SHREECEM.NS - Rank 34.77
2014-07-24 Enter EICHERMOT.NS - Rank 32.88
2014-07-24 Enter PFC.NS - Rank 29.63
2014-07-25 Leave PFC.NS - Rank 27.90
2014-07-25 Rebal ASHOKLEY.NS - Rank 29.14
2014-07-25 Rebal AXISBANK.NS - Rank 40.14
2014-07-25 Rebal BPCL.NS - Rank 30.27
2014-07-25 Rebal CONCOR.NS - Rank 42.54
2014-07-25 Rebal HAVELLS.NS - Rank 33.57
2014-07-25 Rebal ICICIBANK.NS - Rank 28.78
2014-07-25 Rebal LT.NS - Rank 35.62
2014-07-25 Rebal MOTHERSUMI.NS - Rank 29.60
2014-07-25 Rebal PNB.NS - Rank 29.44
2014-07-25 Rebal SBIN.NS - Rank 33.82
2014-07-25 Rebal SHREECEM.NS - Rank 37.58
2014-07-25 Enter EICHERMOT.NS - Rank 34.59
2014-07-25 Enter PETRONET.NS - Rank 29.75
2014-07-28 Leave ASHOKLEY.NS - Rank 26.90
2014-07-28 Rebal AXISBANK.NS - Rank 37.76
2014-07-28 Rebal BPCL.NS - Rank 27.34
2014-07-28 Rebal CONCOR.NS - Rank 37.34
2014-07-28 Rebal HAVELLS.NS - Rank 32.27
2014-07-28 Rebal ICICIBANK.NS - Rank 28.04
2014-07-28 Rebal LT.NS - Rank 32.41
2014-07-28 Rebal MOTHERSUMI.NS - Rank 33.21
2014-07-28 Rebal PETRONET.NS - Rank 29.41
2014-07-28 Rebal PNB.NS - Rank 31.49
2014-07-28 Rebal SBIN.NS - Rank 32.93
2014-07-28 Rebal SHREECEM.NS - Rank 39.10
2014-07-28 Enter EICHERMOT.NS - Rank 35.07
2014-07-28 Enter PFC.NS - Rank 27.19
2014-07-30 Leave BPCL.NS - Rank 28.06
2014-07-30 Leave LT.NS - Rank 26.83
2014-07-30 Rebal AXISBANK.NS - Rank 40.11
2014-07-30 Rebal CONCOR.NS - Rank 40.12
2014-07-30 Rebal HAVELLS.NS - Rank 30.97
2014-07-30 Rebal ICICIBANK.NS - Rank 31.50
2014-07-30 Rebal MOTHERSUMI.NS - Rank 34.60
2014-07-30 Rebal PETRONET.NS - Rank 30.49
2014-07-30 Rebal PFC.NS - Rank 31.60
2014-07-30 Rebal PNB.NS - Rank 37.99
2014-07-30 Rebal SBIN.NS - Rank 34.20
2014-07-30 Rebal SHREECEM.NS - Rank 40.88
2014-07-30 Enter EICHERMOT.NS - Rank 36.10
2014-07-30 Enter ASHOKLEY.NS - Rank 32.29
2014-07-30 Enter TITAN.NS - Rank 29.98
2014-07-31 Leave TITAN.NS - Rank 30.74
2014-07-31 Rebal ASHOKLEY.NS - Rank 33.71
2014-07-31 Rebal AXISBANK.NS - Rank 41.55
2014-07-31 Rebal CONCOR.NS - Rank 39.78
2014-07-31 Rebal HAVELLS.NS - Rank 37.30
2014-07-31 Rebal ICICIBANK.NS - Rank 34.95
2014-07-31 Rebal MOTHERSUMI.NS - Rank 38.18
2014-07-31 Rebal PETRONET.NS - Rank 35.87
2014-07-31 Rebal PFC.NS - Rank 36.63
2014-07-31 Rebal PNB.NS - Rank 41.66
2014-07-31 Rebal SBIN.NS - Rank 34.58
2014-07-31 Rebal SHREECEM.NS - Rank 44.88
2014-07-31 Enter EICHERMOT.NS - Rank 37.48
2014-07-31 Enter PGHH.NS - Rank 31.19
2014-08-01 Leave PGHH.NS - Rank 31.49
2014-08-01 Rebal ASHOKLEY.NS - Rank 33.93
2014-08-01 Rebal AXISBANK.NS - Rank 44.33
2014-08-01 Rebal CONCOR.NS - Rank 36.67
2014-08-01 Rebal HAVELLS.NS - Rank 32.24
2014-08-01 Rebal ICICIBANK.NS - Rank 34.48
2014-08-01 Rebal MOTHERSUMI.NS - Rank 35.42
2014-08-01 Rebal PETRONET.NS - Rank 37.81
2014-08-01 Rebal PFC.NS - Rank 34.10
2014-08-01 Rebal PNB.NS - Rank 41.39
2014-08-01 Rebal SBIN.NS - Rank 34.42
2014-08-01 Rebal SHREECEM.NS - Rank 44.25
2014-08-01 Enter EICHERMOT.NS - Rank 37.08
2014-08-01 Enter MARUTI.NS - Rank 34.32
2014-08-04 Leave HAVELLS.NS - Rank 29.66
2014-08-04 Rebal ASHOKLEY.NS - Rank 36.26
2014-08-04 Rebal AXISBANK.NS - Rank 43.75
2014-08-04 Rebal CONCOR.NS - Rank 36.85
2014-08-04 Rebal ICICIBANK.NS - Rank 36.91
2014-08-04 Rebal MARUTI.NS - Rank 31.97
2014-08-04 Rebal MOTHERSUMI.NS - Rank 37.13
2014-08-04 Rebal PETRONET.NS - Rank 33.84
2014-08-04 Rebal PFC.NS - Rank 33.88
2014-08-04 Rebal PNB.NS - Rank 43.70
2014-08-04 Rebal SBIN.NS - Rank 36.44
2014-08-04 Rebal SHREECEM.NS - Rank 42.08
2014-08-04 Enter EICHERMOT.NS - Rank 38.96
2014-08-04 Enter TATAMTRDVR.NS - Rank 31.49
2014-08-05 Leave PETRONET.NS - Rank 30.15
2014-08-05 Leave TATAMTRDVR.NS - Rank 31.60
2014-08-05 Rebal ASHOKLEY.NS - Rank 37.32
2014-08-05 Rebal AXISBANK.NS - Rank 47.66
2014-08-05 Rebal CONCOR.NS - Rank 37.98
2014-08-05 Rebal ICICIBANK.NS - Rank 39.26
2014-08-05 Rebal MARUTI.NS - Rank 34.96
2014-08-05 Rebal MOTHERSUMI.NS - Rank 39.71
.......

Please accept my apology for bad formatting.

Hi, Very frequently I struggled with float division by zero error. It goes away only after removing multiple tickers data. I went thru existing threads and suggested solutions to supply ```
safediv or safezero

however this parameter is not valid for all indicators. Appreciate any help! Attached is the code 

class Strategy(bt.Strategy):
params = dict(
selcperc=0.15, # percentage of stocks to select from the universe
rperiod=1, # period for the returns calculation, default 1 period
vperiod=252, # lookback period for volatility - default 36 periods
mperiod=126, # lookback period for momentum - default 12 periods
reserve=0.05, # 5% reserve capital
when=bt.timer.SESSION_START,
timer=True,
monthdays=[1],
monthcarry=True
)

def log(self, arg):
        print('{} {}'.format(self.datetime.date(), arg))   

def __init__(self):

bt.indicators.Stochastic(self.datas[0], safediv=True)

    # calculate 1st the amount of stocks that will be selected
    self.selnum = int(len(self.datas) * self.p.selcperc)

    # allocation perc per stock
    # reserve kept to make sure orders are not rejected due to
    # margin. Prices are calculated when known (close), but orders can only
    # be executed next day (opening price). Price can gap upwards
    self.perctarget = (1.0 - self.p.reserve) / self.selnum

    # returns, volatilities and momentums
    rs = [bt.ind.PctChange(d, period=self.p.rperiod) for d in self.datas] # safediv safezero
    vs = [bt.ind.StdDev(ret, period=self.p.vperiod) for ret in rs]
    ms = [bt.ind.ROC(d, period=self.p.mperiod) for d in self.datas]

    # simple rank formula: (momentum * net payout) / volatility
    # the highest ranked: low vol, large momentum, large payout

self.ranks = {d: d.npy * m / v for d, v, m in zip(self.datas, vs, ms)}

    self.ranks = {d: m / v for d, v, m in zip(self.datas, vs, ms)}

    self.add_timer(
        when=self.p.when,
        monthdays=self.p.monthdays,
        monthcarry=self.p.monthcarry
    )

def notify_timer(self, timer, when, *args, **kwargs):
    if self._getminperstatus() < 0:
        self.rebalance()

def rebalance(self):
    # sort data and current rank
    ranks = sorted(
        self.ranks.items(),  # get the (d, rank), pair
        key=lambda x: x[1][0],  # use rank (elem 1) and current time "0"
        reverse=True,  # highest ranked 1st ... please
    )

    # put top ranked in dict with data as key to test for presence
    rtop = dict(ranks[:self.selnum])


    # For logging purposes of stocks leaving the portfolio
    rbot = dict(ranks[self.selnum:])

    # prepare quick lookup list of stocks currently holding a position
    posdata = [d for d, pos in self.getpositions().items() if pos]

    # remove those no longer top ranked
    # do this first to issue sell orders and free cash
    for d in (d for d in posdata if d not in rtop):
        self.log('Leave {} - Rank {:.2f}'.format(d._name, rbot[d][0]))
        self.order_target_percent(d, target=0.0)

    # rebalance those already top ranked and still there
    for d in (d for d in posdata if d in rtop):
        self.log('Rebal {} - Rank {:.2f}'.format(d._name, rtop[d][0]))
        self.order_target_percent(d, target=self.perctarget)
        del rtop[d]  # remove it, to simplify next iteration

    # issue a target order for the newly top ranked stocks
    # do this last, as this will generate buy orders consuming cash
    for d in rtop:
        self.log('Enter {} - Rank {:.2f}'.format(d._name, rtop[d][0]))
        self.order_target_percent(d, target=self.perctarget) 
        
def next(self):
    self.notify_timer(self, self.p.timer, self.p.when)

Error

C:\ProgramData\Anaconda3\lib\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:

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\cerebro.py in runstrategies(self, iterstrat, predata)
   1291                     self._runonce_old(runstrats)
   1292                 else:
-> 1293                     self._runonce(runstrats)
   1294             else:
   1295                 if self.p.oldsync:

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\cerebro.py in _runonce(self, runstrats)
   1650         '''
   1651         for strat in runstrats:
-> 1652             strat._once()
   1653             strat.reset()  # strat called next by next - reset lines
   1654 

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\lineiterator.py in _once(self)
    295 
    296         for indicator in self._lineiterators[LineIterator.IndType]:
--> 297             indicator._once()
    298 
    299         for observer in self._lineiterators[LineIterator.ObsType]:

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\linebuffer.py in _once(self)
    629         self.preonce(0, self._minperiod - 1)
    630         self.oncestart(self._minperiod - 1, self._minperiod)
--> 631         self.once(self._minperiod, self.buflen())
    632 
    633         self.oncebinding()

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\linebuffer.py in once(self, start, end)
    753     def once(self, start, end):
    754         if self.bline:
--> 755             self._once_op(start, end)
    756         elif not self.r:
    757             if not self.btime:

C:\ProgramData\Anaconda3\lib\site-packages\backtrader\linebuffer.py in _once_op(self, start, end)
    770 
    771         for i in range(start, end):
--> 772             dst[i] = op(srca[i], srcb[i])
    773 
    774     def _once_time_op(self, start, end):

ZeroDivisionError: float division by zero

There is no issue with the code. Data wasn't clean hence causing the issue. Once I run the code with clean data, it worked.
Thanks

It looks like a data issue, I get this when I change the frequency from daily to monthly.