3. Newbie looking for help
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Newbie looking for help

  • W

    I've made myself a indicator and a strategy, and I can see it buying and selling. I want to dig more into it to see how I can improve it by printing out the value of my indicator from inside my strategy, but anytime I try to print anything inside my strategy or indicator I get
    <backtrader.linebuffer.LineBuffer object at 0x7feab75cf5f8> or something similar.
    How do I properly print out the values so I can see then improve my strategy & indicator?

    import backtrader as bt
from indicators import efjay_indicator as ei

 class DevMomentum(bt.SignalStrategy):

def __init__(self):
    ey = ei.EyIndicator(self.data)
    self.buy_sig = (ey > 0.45)
    self.sell_sig = (ey < 0.45)

def next(self):
    if not self.position:
        if self.buy_sig:
            self.buy(size=1000)
    else:
        if self.sell_sig:
            self.sell(size=1000)

    `

    0
  • T

    Hi @wysest

    You can do it like this:

    print(self.myindicator[0])

    This will give you the most recent value. Use [-1] for the second most recent and so on. (This is a little different to python lists where [-1] will give you the last item. I think there is a note on this in the docs

    1

  • Quickstart - Our first strategy:

    class TestStrategy(bt.Strategy):

    def log(self, txt, dt=None):
        ''' Logging function for this strategy'''
        dt = dt or self.datas[0].datetime.date(0)
        print('%s, %s' % (dt.isoformat(), txt))

    def __init__(self):
        # Keep a reference to the "close" line in the data[0] dataseries
        self.dataclose = self.datas[0].close

    def next(self):
        # Simply log the closing price of the series from the reference
        self.log('Close, %.2f' % self.dataclose[0])
    2
    B
     1 Reply
  • W
     

    import backtrader as bt
import math

class eIndicator(bt.Indicator):
    lines = ('e',)
    params = (('period', 15),)
    def __init__(self):

        self.e_price_avg = bt.indicators.ExponentialMovingAverage(
            self.data,
            period=self.params.period
        )
        self.e_price_avg_2 = bt.indicators.ExponentialMovingAverage(
            self.data,
            period=self.params.period * 2
        )

        self.price_rev = (self.e_price_avg_2 - self.e_price_avg) / self.e_price_avg
        self.lines.e = self.price_rev

    def next(self):
        pass

    Okay that works inside my strategy to see the line value! Perfect.
    How about inside my indicator (shown above), how can I print the e_price_avg and e_price_avg2 for further info. Thanks! I'm just trying to calculate the percent different between two EMAs. Is this even the proper way to do it? I made it by looking at the Indicator development page but I may have misunderstood some things.
    Thanks!

    0
  • B
    administrators

    @wysest said in Newbie looking for help:

    How about inside my indicator (shown above), how can I print the e_price_avg and e_price_avg2 for further info.

    It would seem obvious following what @ThatBlokeDave and @ab_trader have shown you, which is to print index [0]

    Have you tried it?

    0
    W
     1 Reply
  • W

    @backtrader Ahh. I did try that but I did it inside of the init function, but tried inside the next function this time and it worked. Thanks :)

    0
  • B
    administrators

    You then need to read this: Docs - Platform Concepts and see Stage1 and Stage2

    1
    W
     1 Reply
  • W

    @backtrader Just what I needed, didn't realize this existed. Thanks again! Will be sure to scour the documentation more before any other questions I may have.

    0