Hi *,

i am searching for a possibility to add some additional information to a new order. In my particular case it would be nice to add some general information (e.g. distances to other lines; the first SL in a buy_bracket operation or free text information like "This trade has been opened by signal XY")

In more general: I am searching for a place to store information around a trade opening which can be accessed later on easily within next and holds a reference to the order.

Thanks and BR!
cgi1

Wrote a first version: https://github.com/mementum/backtrader/pull/330

Has someone worked on the Choppiness Index (CHOP) indicator yet?

From tradingview:

The Choppiness Index (CHOP) is an indicator designed to determine if the market is choppy (trading sideways) or not choppy (trading within a trend in either direction).

Implementing the formula should be not very difficult:

100 * LOG10( SUM(ATR(1), n) / ( MaxHi(n) - MinLo(n) ) ) / LOG10(n)
n = User defined period length.
LOG10(n) = base-10 LOG of n
ATR(1) = Average True Range (Period of 1)
SUM(ATR(1), n) = Sum of the Average True Range over past n bars
MaxHi(n) = The highest high over past n bars

@backtrader said in Wrong value of Indicator in another CustomIndicator:

Of course. You can pass any number of data-feed-like objects to indicators. They will be available as self.dataX or the corresponding self.datas[X]

Nice. For reference:

self.sr = SR(self.datas[0], self.atr)

Gives

inside custom indicator SR. So it can be used like

class SR(bt.Indicator):
    def __init__(self, logger, master, fromdate, todate):

        # self.datas[0] is yahoo market data (as default)
        self.atr = self.datas[1]

DONE

Thanks for the good explanation! That´s a view of data feeds I did not had in before.

So self.datas[0] within SR(bt.Indicator) are now set correctly to the values of ATR.

The limitation now is, that there is no YahooDataFeed available anymore, because the data feed gets overwritten by

self.sr = SR(self.atr, [...])

Is it possible to pass multiple data feeds to the indicator?
In this case the market data (YahooDataFeed) and another indicator (ATR)

Something like:

self.sr = SR([self.datas[0], self.atr, self.further_indi], [...])

Generating it new in the custom indicator worked for me:

class SomeStrategy(bt.Strategy):

    def __init__(self):
        self.atr = bt.indicators.ATR(self.datas[0], subplot=False)

class SomeStrategy(bt.Strategy):

    def __init__(self):
        self.atr = bt.indicators.ATR(self.datas[0], plotname="ATR", subplot=True)
        self.sr = SR(logger=self.indi_logger, master=self, fromdate=self.p.fromdate_trading, todate=self.p.todate_trading)

Within my custom indicator SR I need to access the ATR line value within SR->next(). So I pass the whole self to it during init:

class SR(bt.Indicator):

    def __init__(self, logger, master, fromdate, todate):
        self.logger = logger
        self.master = master
        self.atr = self.master.atr

In this example I would assume to access the ATR line value of candle 2001-09-10 using self.atr[0] (which is about 0.51). Instead I get the final ATR line value of today (which is 2.67588x):

Do I need to calculate the shift manually to get the correct ATR value or is there another way to achieve this?

Thanks & BR!

Doc Reference

Thanks for the reply. Just wrote a test:

        try:
            pickle.dump(cerebro, open(pickle_file_path, "wb"))
            logger.debug("Successfully pickled cerebro instance to file (%s)!" %pickle_file_path)
        except:
            logger.exception("Failed to pickle cerebro instance to file (%s)" %pickle_file_path)

but it fails with

File "/Users/g/PycharmProjects/g1trd/master.py", line 236, in runstrat
    pickle.dump(cerebro, open(pickle_file_path, "wb"))
TypeError: can't pickle _thread.RLock objects

Here is how I work in general

I am working on a strategy which works on a bigger set of indicators and price action / swing trading setups. My approach is, to integrate several trading ideas into one strategy.

Said that, there are particular branches for each idea. E.g.:

• master branch holds stable status of strategy
• feature_x branch holds one newly generated stop-rule
• feature_y branch holds a new filter for ranging markets

After developing a new stop-rule / entry / pattern etc I need to backtest it to see if it works for a lot of market data. The normal process here is:

0. Checkout feature_x
1. Backtest it on about 140 symbols for 10-17 years
2. Find bugs / Find market conditions in backtest which I did not concider in before / ...
3. Adjust it
4. If not satisfied: Repeat at 1. If satisfied: Merge it into master branch

So the step of backtesting a huge dataset is done very often. Therefore my interest in having the backtest process done quickly, automated and away from my laptop is very high.

Due to some resource-consuming custom indicator (Support/Resistance) one backtest runs approx. 90 seconds per symbol. I outsourced the backtesting to a powerful linux server which runs 12 backtests in parallel.

Problem

So the problem right now is, that my log entries tell me, at which symbols on which dates the current feature have an impact on (e.g. Your new stop rule triggered on 2008-01-19 on EURUSD=X). But I need a chart to see if the program executes it in a situation which I created it for. So i started to use savefig option (cerebro.plot(style='candlestick', savefig=save_fig, dpi=900, width=32, height=18, numfigs=5)) which has been nicely provided by @xnox, but zooming into it looks like this (even with the provided settings):

Proposal

So my idea is to save all the cerebro data to file (e.g. by a linux server) and load the plotter later (on a normal computer) with the saved data. Do you think this is a reasonable way?

Thanks for the reply.

This means that some lines (a sample line would help) contains prices which can be parse, but the string null that where the volume should be, or is it something else?

Exactly: So sometimes the datafeed provider (in this case Yahoo on 2017-06-08) does not provider any Volume for some of the symbols. E.g. EURHKD=X:

Date,Open,High,Low,Close,Adj Close,Volume
2003-12-01,9.347397,9.278463,9.339722,9.290833,9.290833,null
2003-12-02,9.287244,9.278581,9.393217,9.380319,9.380319,null

2017-06-06,8.783572,8.734257,8.789911,8.784152,8.784152,null
2017-06-08,8.780444,8.732892,8.782912,8.748856,8.748856,0 <<<<< Date of download!

Some symbols are including Volume==0. E.g. EURUSD=X

Date,Open,High,Low,Close,Adj Close,Volume
2003-12-01,1.203398,1.194401,1.204007,1.196501,1.196501,0
2003-12-02,1.196101,1.194600,1.210903,1.208897,1.208897,0

2005-09-20,null,null,null,null,null,null <<<< Some dates are does not even contain any data

2017-06-06,1.127053,1.120523,1.127993,1.127142,1.127142,0
2017-06-08,1.126507,1.127142,1.119946,1.122083,1.122083,0 <<<<< Date of download!

Meanwhile on the same date a lot symbols (e.g. IFX.DE) contain Volume and works as expected.

Date,Open,High,Low,Close,Adj Close,Volume
2000-03-14,71.400002,80.000000,71.400002,78.900002,78.900002,9579700
2000-03-15,76.900002,76.949997,70.800003,73.040001,73.040001,5855009

Hope this helps. If you need further information please let me know.