Zero division error on developed indicators

vaclavku

Hi, I try to develop a new simple indicator about however zero division error araises (something related to the acc dist).
I've checked the forum as well as the solution for the RSI, however I'm still short a little bit.
Could someone advise?
I've tried two approaches:

Except: However the "ZeroDivisionError: float division by zero" persists.

    lines = ('accdist',)
    
    def __init__(self):
        super(Accdist, self).__init__()
        
        try:
            mfm = ((self.data.close - self.data.low) - (self.data.high - self.data.close))/(self.data.high - self.data.low)
        except ZeroDivisionError:
            mfm = 0.0

        mfv = mfm * self.data.volume  
        self.lines.accdist =  mfv + mfv(-1)```

2. Conditional approach, however there is an issue with the object. 
```class Accdist(bt.Indicator):
    lines = ('accdist',)

    def __init__(self):
        super(Accdist, self).__init__()
        
        numerator = ((self.data.close - self.data.low) - (self.data.high - self.data.close))
        denominator = (self.data.high - self.data.low)

        zero = 0.0
        mfm = numerator / denominator if numerator else zero
 
        mfv = mfm * self.data.volume 
        
        self.lines.accdist =  mfv + mfv(-1)```

Anyone can help me with a simple way to handle it.
Many thanks
v

vaclavku

Hello, I've found the issue with condition bt.If (in this nice threat: https://community.backtrader.com/topic/531/indicator-development-missing-a-key-piece/3), that's fine and I could not see the link. However, my issue still persists even if the condition works fine:
ZeroDivisionError: float division by zero

Anyone can explain it?

    lines = ('accdist', )

    def __init__(self):
        super(Accdist, self).__init__()
        
        numerator = ((self.data.close - self.data.low) - (self.data.high - self.data.close))
        denominator = (self.data.high - self.data.low)        
        mfm = bt.If(self.data.high > self.data.low, numerator/denominator, 0)         
        mfv = mfm * self.data.volume         
        self.lines.accdist =  mfv + mfv(-1)```

Many thanks,
v

backtrader

@vaclavku said in Zero division error on developed indicators:

I've found the issue with condition bt.If (in this nice threat: https://community.backtrader.com/topic/531/indicator-development-missing-a-key-piece/3),

I guess your intention is to say that you have found out how to address your issue with information from that thread.

The issue at hand is that you are not managing the division by zero condition. You need DivByZero, which executes a division with parts (i.e.: lines) working inside backtrader and delivers a specific result if a division by zero happens.

See here: https://community.backtrader.com/topic/1179/min-period-for-custom-stochasticrsi-indicator/4

vaclavku

Hello administor, you're right as always.
And thanks for the clue about the DivByZero.