How to overlay two indicators?

[flexelem]

Hi there,

I know self.I() has overlay parameter to make overlap current indicator on price chart but I want to overlay two different (both of them are oscillators with range -100,100). As you can see from the picture I want to overlay EMA and SMA indicators. Thanks!

[kernc]

To join multiple indicator lines on the same indicator plot, just return them together in a tuple. E.g.:

class MyStrategy(Strategy):
    def init(self):

        @self.I
        def my_indicator():
            ema = EMA(self.data.High, 21)
            return ema, SMA(ema, 4)

[flexelem]

Hi @kernc,

Thanks a lot for helping out. I am kinda python dummy. And trying to find where to import @self.I. Here is the very basic code I am running on. And I have two questions;

1. How to import @self.I?
2. Should I use my_indicator def in computing side or this is only for plotting?

from backtesting import Strategy
from backtesting.lib import crossover
from talib import EMA, SMA


class WTCross(Strategy):
    n1 = 10
    n2 = 21

    def init(self):
        close = self.data.Close
        high = self.data.High
        low = self.data.Low
        ap = (high + low + close) / 3

        esa = EMA(ap, self.n1)
        d = EMA(abs(ap - esa), self.n1)
        self.ci = (ap - esa) / (0.015 * d)
        self.wt1 = self.I(EMA, self.ci, self.n2)
        self.wt2 = self.I(SMA, self.wt1, 4)

    def next(self):
        if crossover(self.wt1, self.wt2):
            self.buy()
        elif crossover(self.wt2, self.wt1):
            self.sell()

    @self.I
    def my_indicator(self):
        wt1 = self.I(EMA, self.ci, self.n2)
        return wt1, self.I(SMA, self.wt1, 4)

Thanks

[kernc]

See my answer above revised. Using it as a decorator is equivalent to a normal self.I() function call.

[flexelem]

gotcha. thanks @kernc