How could I plot Crossover Signal on master window(plotinfo.plotmaster == self.datas[0]) as triangle indicating where it happens??

[xyshell]

Hi everyone.
Currently I want to plot some Crossover Signal (bt.ind.CrossOver) on the price to gain some insight.
I want to plot it as triangle (just like the buy and sell point) with probably different colors and directions (up-triangle indicating it's crossing up, down-triangle indicating it's crossing down), just like selling gives a red downside triangle and buying gives a green upside triangle.
Is there anyone know how to do that?

[xyshell]

I think I found some part of solution in this article.

https://www.backtrader.com/blog/posts/2016-12-10-buysellarrows/buysellarrows/

But this only re-defines buy-sell signal pattern, not exactly what I want.

[ab_trader]

You may want to create custom indicator with two lines up and down which has a CrossOver indicator inside. Something like this (not tested):

class CrossOverWithArrows(bt.Indicator):

    lines = ('up', 'down')

    plotlines = dict(
        up=dict(marker='$\u21E7$', markersize=12.0),
        down=dict(marker='$\u21E9$', markersize=12.0)

    def __init__(self):
        up = bt.ind.CrossUp(smthng, smthng)
        down = bt.ind.CrossDown(smthng, smthng)

[xyshell]

@ab_trader Cool, I'll try it latter!

[xyshell]

@ab_trader said in How could I plot Crossover Signal on master window(plotinfo.plotmaster == self.datas[0]) as triangle indicating where it happens??:

plotlines = dict(
    up=dict(marker='$\u21E7$', markersize=12.0),
    down=dict(marker='$\u21E9$', markersize=12.0)

Thanks for your advice, here is what I've done and it works exactly the same as expected.

import datetime

import backtrader as bt


class DoubleSMAWithLoc(bt.Indicator):

    lines = ('fast', 'slow', 'loc')

    params = (
        ('pfast', 10),
        ('pslow', 30),
    )

    plotlines = dict(loc=dict(_plotskip='True',))

    def __init__(self):
        self.l.fast = bt.ind.SMA(self.data, period=self.p.pfast)
        self.l.slow = bt.ind.SMA(self.data, period=self.p.pslow)
        self.l.loc = self.data.close


class CrossOverWithArrows(bt.Indicator):

    lines = ('up', 'down')

    plotlines = (
        ('up', dict(ls='', marker='^', markersize=8.0, color='green', fillstyle='full')),
        ('down', dict(ls='', marker='v', markersize=8.0, color='red', fillstyle='full'))
    )

    def __init__(self):
        self.cross_up = bt.ind.CrossUp(self.data.fast, self.data.slow)
        self.cross_down = bt.ind.CrossDown(self.data.fast, self.data.slow)
        self.l.up = bt.If(self.cross_up, self.data.loc, -1)
        self.l.down = bt.If(self.cross_down, self.data.loc, -1)


class SMACross(bt.Strategy):

    params = (
        ('pfast', 10),
        ('pslow', 30),
    )

    def __init__(self):
        self.sma = DoubleSMAWithLoc(
            self.datas[0],
            pfast=self.p.pfast, pslow=self.p.pslow,
            plotmaster=self.datas[0])
        self.cross = CrossOverWithArrows(
            self.sma,
            plotmaster=self.datas[0])


if __name__ == '__main__':
    cerebro = bt.Cerebro(stdstats=False)
    cerebro.addstrategy(SMACross)
    datapath = 'datas/orcl-1995-2014.txt'

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

    cerebro.adddata(data)
    cerebro.addwriter(bt.WriterFile, csv=True, out='temp.csv')
    cerebro.run()
    cerebro.plot()

[slashAmoment]

@xyshell I think this will be better
('up', dict(_skipnan=True, ls='', marker='^', markersize=8.0, color='green', fillstyle='full')),
('down', dict(_skipnan=True, ls='', marker='v', markersize=8.0, color='red', fillstyle='full')),
and
self.l.up = bt.If(self.cross_up, self.data.loc, float('NaN'))
self.l.down = bt.If(self.cross_down, self.data.loc,float('NaN'))