TypeError: __init__() takes 1 positional argument but 2 were given

[Chricco94]

hi, i'm trying to backtest this strategy:

class WaveTrendStrategy(bt.Strategy):

def __init__(self) :
    n1 = 21
    n2 = 14
    obLevel1 = 60
    obLevel1 = 60
    obLevel2 = 53
    osLevel1 = -60
    osLevel2 = -53
    hlc3 = (self.data.high+self.data.low+self.data.close)/3
    ap = hlc3 
    esa = bt.ind.EMA(ap, n1)
    d = bt.ind.EMA(abs(ap - esa), n1)
    ci = (ap - esa) / (0.015 * d)
    tci = bt.ind.EMA(ci, n2)
    wt1 = tci
    wt2 = bt.ind.SMA(wt1,4)
    longCondition  = bt.ind.CrossOver(wt2,osLevel2)
    shortCondition = bt.ind.CrossUnder(wt2,obLevel2)
    
    
def next(self):
    if longCondition:
            self.buy()
    
    elif shortCondition:
        self.sell()

but i get TypeError: init() takes 1 positional argument but 2 were given.

Someone can show me where i'm wrong? Thanks a lot.

[davidavr]

@chricco94 That error is coming from your use of EMA. You need to name the period parameter so use

esa = bt.ind.EMA(ap, period=n1)

instead of

esa = bt.ind.EMA(ap, n1)

BT makes heavy use of meta classes which can be confusing at times.

There are a couple of other issues in your code:

• There is no CrossUnder indicator in BT
• You aren't storing the longCondition and shortCondition indicators in self so you cannot access them in next()

[Chricco94]

@davidavr thank you, it worked!