Is bt.And only allowed to have 2 elements for the condition description as well?
Would I be able to build or chain together a higher number of elements with and?
for example:

condition = bt.And(d(-3) > e(-2), e(-2) > f(-1)) \
            and bt.And(i(-5) > g(-4), g(-4) > d(-3))

Thanks.

@ab_trader said in IndexError: array index out of range:

infline = bt.LineNum(float('Inf'))

thanks, but the change to infline still produces the same error:
TypeError: __bool__ should return bool, returned LineOwnOperation

x is different from y, because it returns d(-1) instead of e(-1),
unless I am stating the bt.If incorrectly.

@ab_trader

Thank you, I have replaced the [] with () and the out of range error has gone, but now I have another error:

    def __init__(self):

        x = bt.If(d(-3) > e(-2) > f(-1), d(-1), float('Inf'))  # new error here

 # error message: TypeError: __bool__ should return bool, returned LineOwnOperation     

Thanks again.

Why is this error message coming up with this line?

# error message:
    return self.array[self.idx + ago]
IndexError: array index out of range   

    def __init__(self):

        x = bt.If(d[-3] > e[-2] > f[-1], d[-1], float('Inf'))
        y = bt.If(d[-3] > e[-2] > f[-1], e[-1], float('Inf'))
        z = bt.If(y < float('Inf'), y[-1], float('Inf'))  # error message line

Thanks.

When BackTrader is connected to a broker api (https://github.com/ftomassetti/backtrader-oandav20),
does BackTrader keep track of existing positions locally/internally, or does it retrieve that data from the broker api?
Can the user choose which option?

Thanks.

@backtrader
thank you very much for your time and assistance, you have been very helpful.

@ab_trader
I have no coding experience at all, everything i've posted here is just what I took from the documentation, so if you have time; could you show me how to only have the self.data.low results in the line?

• how to define a placeholder for 9000?
• how and where do I create a self.variable that represents only the True return of a function/operator? in def __init__(self):?

if only_low[-1]>only_low[-2]:
        	self.buy()  # enter long

"Say element [-2] has no low value (condition didn't meet) and element[-1] has low value. What do you expect from the script?"
That statement was just to show I wanted to use the most recent previous low value and the one before that for trading logic; it already assumes I have created a line without the false value (9000)return.

thanks for you help.

@ab_trader said in bt.If operator/function:

low_or_9000 = bt.If(sma1(-2) > self.data.close(-1), self.data.low, 9000.0)

Wouldn't that create a "line" with the value "9000" in it still?
I would like to create a line from function/operator result without "9000" and a line with only "self.data.low".

Is there a version of bt.If function that only returns the True value? (instead of the True value or False value)
and
can an indexed value be used within bt.If?
and
would I be able to call previous occurrences of function result with [-1], [-2], for a strategy?

From the documentation:
https://backtrader.com/docu/concepts/#some-non-overriden-operatorsfunctions

class MyStrategy(bt.Strategy):

    def __init__(self):

        sma1 = btind.SMA(self.data.close, period=15)
        high_or_low = bt.If(sma1 > self.data.close, self.data.low, self.data.high)# returns Low if True, High if False
        sma2 = btind.SMA(high_or_low, period=15)

I would like to use the function/operator like this:

class MyStrategy(bt.Strategy):

    def __init__(self):

        sma1 = btind.SMA(self.data.close, period=15)
        only_low = bt.If(sma1[-2] > self.data.close[-1], self.data.low) # if sma1[-2]>close[-1] then return just the Low value
        sma2 = btind.SMA(high_or_low, period=15)

and then use it in strategy like this:

def next(self):
        if only_low[-1]>only_low[-2]:
        	self.buy()  # enter long

If bt.If cannot do this, which other function/operator would be able to?
or how would I modify bt.If to do this?

I tried to filter out 2nd result with below, but it does not work:

class MyStrategy(bt.Strategy):

    def __init__(self):

        sma1 = btind.SMA(self.data.close, period=15)
        low_or_9000 = bt.If(sma1[-2] > self.data.close[-1], self.data.low, 9000.0) # if sma1>close ture then return Low, false returns 9000.0
        sma2 = btind.SMA(high_or_low, period=15)
	self.data.only_low = low_or_9000 < 9000.0