Plotting a boolean indicator

[Marc Hanbuerger]

Hi there,
I am developing my own indicator and for debugging purposes I would like to plot the signal it generates over the actual data points, much like the buy/ sell arrows.
Here is some sample code so far (removed all unnecessary code for clarity purposes and generated random True / False indicator), as you can see, it plots a 1 if the indicator is true in a subplot. How do I convert that into an arrow above / below the candle?
Many thanks!
Marc

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)
import backtrader as bt
import datetime  # For datetime objects
import os.path  # To manage paths
import sys  # To find out the script name (in argv[0])
import random


class DummyInd(bt.Indicator):
    lines = ('dummyline',)

    def next(self):
        if random.randint(0, 100) > 90:
            result = 1
        else:
            result =0
        self.lines.dummyline[0] = result


# Create a Stratey
class TestStrategy(bt.Strategy):

    def __init__(self):
        self.myindicator = DummyInd()

    def next(self):
        pass


cerebro = bt.Cerebro()

cerebro.addstrategy(TestStrategy)

modpath = os.path.dirname(os.path.abspath(sys.argv[0]))
datapath = modpath + "\\datas\\orcl-1995-2014.txt"

data = bt.feeds.YahooFinanceCSVData(
    dataname=datapath,
    # Do not pass values before this date
    fromdate=datetime.datetime(2000, 1, 1),
    # Do not pass values after this date
    todate=datetime.datetime(2000, 12, 31),
    reverse=False)

cerebro.adddata(data)

cerebro.broker.setcash(100000.0)
cerebro.run()
cerebro.plot()

[backtrader]

To do that, look at the definition of how lines are plotted in the BuySell observer.

https://github.com/mementum/backtrader/blob/700380c8bc41ab9da8295cfc7b64091bab75866b/backtrader/observers/buysell.py#L47-L54

[Marc Hanbuerger]

Hi Backtrader,

Thanks a lot! that worked...
Here the code in case someone else needs it:

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)
import backtrader as bt
import datetime  # For datetime objects
import os.path  # To manage paths
import sys  # To find out the script name (in argv[0])
import random


class DummyInd(bt.Indicator):
    lines = ('dummyline',)
    plotinfo = dict(plot=True, subplot=False, plotlinelabels=True)
    plotlines = dict(dummyline=dict(marker='$\u21E9$', markersize=6.0, color='red', fillstyle='full', ls='') )
    params = (
        ('barplot', False),  # plot above/below max/min for clarity in bar plot
        ('bardist', 0.055),  # distance to max/min in absolute perc
    )

    def next(self):


        if random.randint(0, 100) > 96: # to get a ~4% chance of this dummy indicator triggering
           self.lines.dummyline[0] = self.datas[0].high[0]
        else:
            pass


# Create a Stratey
class TestStrategy(bt.Strategy):

    def __init__(self):
        self.myindicator = DummyInd()

    def next(self):
        pass


cerebro = bt.Cerebro()

cerebro.addstrategy(TestStrategy)

modpath = os.path.dirname(os.path.abspath(sys.argv[0]))
datapath = modpath + "\\datas\\orcl-1995-2014.txt"

data = bt.feeds.YahooFinanceCSVData(
    dataname=datapath,
    # Do not pass values before this date
    fromdate=datetime.datetime(2000, 1, 1),
    # Do not pass values after this date
    todate=datetime.datetime(2000, 12, 31),
    reverse=False)

cerebro.adddata(data)

cerebro.broker.setcash(100000.0)
cerebro.run()
cerebro.plot()

and here a screenshot of the indicator: