True strength indicator help
I'm trying to create the mentioned indicator, but as newb, I have not grasped the concept of how stuff should be done!
So this is what I'm trying to do:
class TrueStrengthIndicator(bt.Indicator): ... ... def __init__(self): .... ema1 = bt.indicators.ExponentialMovingAverage(self.data - self.data[-1], period=self.params.lperiod)
I know that when the first bar is handled, there is no self.data[-1], but how can I handle this.
See Docs - Platform Concepts and specifically the section Lines: DELAYED indexing
During the declaration phase the
[x]operator makes no sense, because values are not yet there (even if preloading creates the false impression it does)
(-x)returns an object which will later deliver the delayed values. In your case:
self.data - self.data(-1)
Because you can obviously omit
It seems a nice indicator. Will get added along small details.
Should be something like this acoording to Stockcharts - TSI
class TrueStrengthIndicator(bt.Indicator): alias = ('TSI',) params = ( ('period1', 25), ('period2', 13), ) lines = ('tsi',) def __init__(self): pc = self.data - self.data(-1) smooth1 = bt.ind.EMA(bt.ind.EMA(pc, period=self.p.period1), period=self.p.period2) smooth2 = bt.ind.EMA(bt.ind.EMA(abs(pc), period=self.p.period1), period=self.p.period2) self.lines.tsi = 100.0 * (smooth1 / smooth2)
Thx for the input, as you know now, I have to digest this a little bit to fully understand what you have written.
It works perfectly, thx for the input about delayed indexing! I'm not sure how long it would have taken me to find this!
Probably the best way is to look at other indicators which are already part of the platform.
UpDay(which is nothing else but the definition made by Wilder to later define RSI)
class UpDay(Indicator): lines = ('upday',) def __init__(self): self.lines.upday = Max(self.data - self.data(-1), 0.0)
Maxis not a typo. Whilst
abscan be overridden (for the example above with
If you look into
Ichimokuyou can also see line forwarding.
I actually looked at just that example, but I got confused about when to use what, [ ] or ( ). As I said, I'm learning the platform right now, so I'm thankful for the input.