This is the user guide for using pysystemtrade as a backtesting platform. Before reading this you should have gone through the introduction.
Related documents:
- Storing futures and spot FX data
- Using pysystemtrade as a production trading environment
- Connecting pysystemtrade to interactive brokers
- Recent undocumented changes
This guide is divided into four parts. The first 'How do I?' explains how to do many common tasks. The second part 'Guide' details the relevant parts of the code, and explains how to modify or create new parts. The third part 'Processes' discusses certain processes that cut across multiple parts of the code in more detail. The final part 'Reference' includes lists of methods and parameters.
- How do I?
- How do I.... Experiment with a single trading rule and instrument
- How do I....Create a standard futures backtest
- How do I....Create a futures backtest which estimates parameters
- How do I....See intermediate results from a backtest
- How do I....See how profitable a backtest was
- How do I....Change backtest parameters
- How do I....Run a backtest on a different set of instruments
- How do I.... run the backtest only on more recent data
- How do I....Run a backtest on all available instruments
- How do I.... Exclude some instruments from the backtest
- How do I.... Exclude some instruments from having positive instrument weights
- How do I....Create my own trading rule
- How do I....Use different data or instruments
- How do I... Save my work
- Guide
- Data
- Configuration
- System
- Stages
- Stage 'wiring'
- Writing new stages
- Specific stages
- Stage: Raw data
- Stage: Rules
- Trading rules
- The Rules class, and specifying lists of trading rules
- Stage: Forecast scale and cap ForecastScaleCap class
- Stage: Forecast combine ForecastCombine class
- Stage: Position scaling
- Stage: Creating portfolios Portfolios class
- Stage: Accounting
- Processes
- File names
- Logging
- Optimisation
- Estimating correlations and diversification multipliers
- Capital correction: Varying capital
- Reference
- Table of standard system.data and system.stage methods
- Explanation of columns
- System object
- Data object
- Raw data stage
- Trading rules stage (chapter 7 of book)
- Forecast scaling and capping stage (chapter 7 of book)
- Combine forecasts stage (chapter 8 of book)
- Position sizing stage (chapters 9 and 10 of book)
- Portfolio stage (chapter 11 of book)
- Accounting stage
- Configuration options
- Table of standard system.data and system.stage methods
Created by gh-md-toc
- How do I.... Experiment with a single trading rule and instrument
- How do I....Create a standard futures backtest
- How do I....Create a futures backtest which estimates parameters
- How do I....See intermediate results from a backtest
- How do I....See how profitable a backtest was
- How do I....Change backtest parameters
- How do I....Run a backtest on a different set of instruments
- How do I....Create my own trading rule
- How do I....Use different data or instruments
- How do I... Save my work
Although the project is intended mainly for working with trading systems, it's possible to do some limited experimentation without building a system. See the introduction for an example.
This creates the staunch systems trader example defined in chapter 15 of my book, using the csv data that is provided, and gives you the position in the Eurodollar market:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.portfolio.get_notional_position("EDOLLAR")See standard futures system for more.
This creates the staunch systems trader example defined in chapter 15 of my book, using the csv data that is provided, and estimates forecast scalars, instrument and forecast weights, and instrument and forecast diversification multipliers:
from systems.provided.futures_chapter15.estimatedsystem import futures_system
system=futures_system()
system.portfolio.get_notional_position("EDOLLAR")This will give you the raw forecast (before scaling and capping) of one of the EWMAC rules for Eurodollar futures in the standard futures backtest:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.rules.get_raw_forecast("EDOLLAR", "ewmac64_256")For a complete list of possible intermediate results, use print(system) to
see the names of each stage, and then stage_name.methods(). Or see this
table and look for rows marked with D for
diagnostic. Alternatively type system to get a list of stages, and
system.stagename.methods() to get a list of methods for a stage (insert the
name of the stage, not stagename).
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.accounts.portfolio().stats() ## see some statistics
system.accounts.portfolio().curve().plot() ## plot an account curve
system.accounts.portfolio().percent.curve().plot() ## plot an account curve in percentage terms
system.accounts.pandl_for_instrument("US10").percent.stats() ## produce % statistics for a 10 year bond
system.accounts.pandl_for_instrument_forecast("EDOLLAR", "carry").sharpe() ## Sharpe for a specific trading rule variationFor more information on what statistics are available, see the relevant guide section.
The backtest looks for its configuration information in the following places:
- Elements in the configuration object
- If not found, in: the private yaml config if it exists here
/private/private_config.yaml - If not found, in: Project defaults
Configuration objects can be loaded from yaml files, or created with a dictionary. This suggests that you can modify the systems behaviour in any of the following ways:
- Change or create a configuration yaml file, read it in, and create a new system
- Change a configuration object in memory, and create a new system with it.
- Change a configuration object within an existing system (advanced)
- Create a private config yaml
/private/private_config.yaml(this useful if you want to make a global change that affects all your backtest) - Change the project defaults (definitely not recommended)
For a list of all possible configuration options, see this table.
If you use options 2 or 3, you can save the config to a yaml file.
Configurations in this project are stored in yaml files. Don't worry if you're not familiar with yaml; it's just a nice way of creating nested dicts, lists and other python objects in plain text. Just be aware that indentations are important, just in like python, to create nesting.
You can make a new config file by copying this
one, and modifying
it. Best practice is to save this as
pysystemtrade/private/this_system_name/config.yaml (you'll need to create a
couple of directories first).
You should then create a new system which points to the new config file:
from sysdata.config.configdata import Config
from systems.provided.futures_chapter15.basesystem import futures_system
my_config=Config("private.this_system_name.config.yaml")
system=futures_system(config=my_config)See here for how to specify filenames in pysystemtrade.
We can also modify a configuration object from a loaded system directly, and then create a new system with it:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
new_config=system.config
new_idm=1.1 ## new IDM
new_config.instrument_div_multiplier=new_idm
## Heres an example of how you'd change a nested parameter
## If the element doesn't yet exist in your config:
system.config.volatility_calculation=dict(days=20)
## If it does exist:
system.config.volatility_calculation['days']=20
system=futures_system(config=new_config)This is useful if you're experimenting interactively 'on the fly'.
If you opt for (3) you will need to understand about system caching and how defaults are handled. To modify the configuration object in the system directly:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
## Anything we do with the system may well be cached and will need to be cleared before it sees the new value...
new_idm=1.1 ## new IDM
system.config.instrument_div_multiplier=new_idm
## If we change anything that is nested, we need to change just one element to avoid clearing the defaults:
# So, do this:
system.config.volatility_calculation['days']=20
# Do NOT do this - it will wipe out all the other elements in the volatility_calculation dictionary:
# system.config.volatility_calculation=dict(days=20)
## The config is updated, but to reiterate anything that uses it will need to be cleared from the cacheBecause we don't create a new system and have to recalculate everything from scratch, this can be useful for testing isolated changes to the system if you know what you're doing.
This makes sense if you want to make a global change to a particular parameter rather than constantly including certain things in your configuration files. Anything in this file will overwrite the system defaults, but will in turn be overwritten by the backtest configuration .yaml file. This file will also come in very handy when it comes to using pysystemtrade as a production trading environment
I don't recommend changing the defaults - a lot of tests will fail for a start - but should you want to more information is given here.
Fixed instrument weights: You need to change the instrument weights in the configuration. Only instruments with weights have positions produced for them. Estimated instrument weights: You need to change the instruments section of the configuration.
There are two easy ways to do this - change the config file, or the config object already in the system (for more on changing config parameters see 'change backtest parameters' ). You also need to ensure that you have the data you need for any new instruments. See 'use my own data' below.
You should make a new config file by copying this
one. Best practice is
to save this as pysystemtrade/private/this_system_name/config.yaml (you'll
need to create this directory).
For fixed weights, you can then change this section of the config:
instrument_weights:
EDOLLAR: 0.117
US10: 0.117
EUROSTX: 0.20
V2X: 0.098
MXP: 0.233
CORN: 0.233
instrument_div_multiplier: 1.89
You may also have to change the forecast_weights, if they're instrument specific:
forecast_weights:
EDOLLAR:
ewmac16_64: 0.21
ewmac32_128: 0.08
ewmac64_256: 0.21
carry: 0.50
*At this stage you'd also need to recalculate the diversification multiplier (see chapter 11 of my book). See estimating the forecast diversification multiplier.
For estimated instrument weights you'd change this section:
instruments: ["EDOLLAR", "US10", "EUROSTX", "V2X", "MXP", "CORN"]
Note that if moving from fixed to estimated instrument weights (by changing system.config.use_instrument_weight_estimates to True), the set of instruments selected in your system.config.instrument_weights will be ignored; if you want to continue using this same set of instruments, you need to say so:
system.config.instruments = list(system.config.instrument_weights.keys())(The IDM will be re-estimated automatically)
You may also need to change this section, if you have different rules for each instrument:
rule_variations:
EDOLLAR: ['ewmac16_64','ewmac32_128', 'ewmac64_256', 'carry']
You should then create a new system which points to the new config file:
from sysdata.config.configdata import Config
my_config=Config("private.this_system_name.config.yaml")
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(config=my_config)See here for how to specify filenames in pysystemtrade.
We can also modify the configuration object in the system directly:
For fixed weights:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
new_config=system.config
new_weights=dict(SP500=0.5, KR10=0.5) ## create new weights
new_idm=1.1 ## new IDM
new_config.instrument_weights=new_weights
new_config.instrument_div_multiplier=new_idm
system=futures_system(config=new_config)For estimated weights:
from systems.provided.futures_chapter15.estimatedsystem import futures_system
system=futures_system()
new_config=system.config
new_config.instruments=["SP500", "KR10"]
del(new_config.rule_variations) ## means all instruments will use all trading rules
# this stage is optional if we want to give different instruments different sets of rules
new_config.rule_variations=dict(SP500=['ewmac16_64','carry'], KR10=['ewmac32_128', 'ewmac64_256', 'carry'])
system=futures_system(config=new_config)You need to set the start_date in the .yaml backtest configuration file:
## Note you must use this format
start_date: '2000-01-19'
If there are is no instrument_weights or instruments elements in the config, then the backtest will be run over all available instruments in the data.
Refer to the instruments document.
Refer to the instruments document.
At some point you should read the relevant guide section 'rules' as there is much more to this subject than I will explain briefly here.
A trading rule consists of:
- a function
- some data (specified as positional arguments)
- some optional control arguments (specified as key word arguments)
So the function must be something like these:
def trading_rule_function(data1):
## do something with data1
def trading_rule_function(data1, arg1=default_value):
## do something with data1
## controlled by value of arg1
def trading_rule_function(data1, data2):
## do something with data1 and data2
def trading_rule_function(data1, data2, arg1=default_value, arg2=default_value):
## do something with data1
## controlled by value of arg1 and arg2... and so on.
Functions must return a Tx1 pandas dataframe.
We can either modify the YAML file or the configuration object we've already loaded into memory. See 'changing backtest parameters' for more details. If you want to use a YAML file you need to first save the function into a .py module, so it can be referenced by a string (we can also use this method for a config object in memory).
For example the rule imported like this:
from systems.futures.rules import ewmacCan also be referenced like so: systems.futures.rules.ewmac
Also note that the list of data for the rule will also be in the form of string
references to methods in the system object. So for example to get the daily
price we'd use the method system.rawdata.daily_prices(instrument_code) (for a
list of all the data methods in a system see stage
methods or type system.rawdata.methods() and
system.rawdata.methods()). In the trading rule specification this would be
shown as "rawdata.daily_prices".
If no data is included, then the system will default to passing a single data
item - the price of the instrument. Finally if any or all the other_arg
keyword arguments are missing then the function will use its own defaults.
At this stage we can also remove any trading rules that we don't want. We also ought to modify the forecast scalars (See forecast scale estimation, forecast weights and probably the forecast diversification multiplier (see estimating the forecast diversification multiplier). If you're estimating weights and scalars (i.e. in the pre-baked estimated futures system provided) this will be automatic.
If you're using fixed values (the default) then if you don't include a forecast scalar for the rule, it will use a value of 1.0. If you don't include forecast weights in your config then the system will default to equally weighting. But if you include forecast weights, but miss out the new rule, then it won't be used to calculate the combined forecast.
Here's an example for a new variation of the EWMAC rule. This rule uses two types of data - the price (stitched for futures), and a precalculated estimate of volatility.
YAML: (example)
trading_rules:
.... existing rules ...
new_rule:
function: systems.futures.rules.ewmac
data:
- "rawdata.daily_prices"
- "rawdata.daily_returns_volatility"
other_args:
Lfast: 10
Lslow: 40
#
#
## Following section is for fixed scalars, weights and div. multiplier:
#
forecast_scalars:
..... existing rules ....
new_rule=10.6
#
forecast_weights:
.... existing rules ...
new_rule=0.10
#
forecast_div_multiplier=1.5
#
#
## Alternatively if you're estimating these quantities use this section:
#
use_forecast_weight_estimates: True
use_forecast_scale_estimates: True
use_forecast_div_mult_estimates: True
rule_variations:
EDOLLAR: ['ewmac16_64','ewmac32_128', 'ewmac64_256', 'new_rule']
#
# OR if all variations are the same for all instruments
#
rule_variations: ['ewmac16_64','ewmac32_128', 'ewmac64_256', 'new_rule']
#
Python (example - assuming we already have a config object loaded to modify)
from systems.trading_rules import TradingRule
# method 1
new_rule = TradingRule(
dict(function="systems.futures.rules.ewmac", data=["rawdata.daily_prices", "rawdata.daily_returns_volatility"],
other_args=dict(Lfast=10, Lslow=40)))
# method 2 - good for functions created on the fly
from systems.futures.rules import ewmac
new_rule = TradingRule(dict(function=ewmac, data=["rawdata.daily_prices", "rawdata.daily_returns_volatility"],
other_args=dict(Lfast=10, Lslow=40)))
## both methods - modify the configuration
config.trading_rules['new_rule'] = new_rule
## If you're using fixed weights and scalars
config.forecast_scalars['new_rule'] = 7.0
config.forecast_weights = dict(...., new_rule=0.10) ## all existing forecast weights will need to be updated
config.forecast_div_multiplier = 1.5
## If you're using estimates
config.use_forecast_scale_estimates = True
config.use_forecast_weight_estimates = True
use_forecast_div_mult_estimates: True
config.rule_variations = ['ewmac16_64', 'ewmac32_128', 'ewmac64_256', 'new_rule']
# or to specify different variations for different instruments
config.rule_variations = dict(SP500=['ewmac16_64', 'ewmac32_128', 'ewmac64_256', 'new_rule'], US10=['new_rule', ....)Once we've got the new config, by which ever method, we just use it in our system, eg:
## put into a new system
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(config=config)The default data used for the simulation is .csv files for futures stitched prices, fx and contract related data. It's my intention to update this and try to keep it reasonably current with each release. The data is stored in the data/futures directory
You can update that data, if you wish. Be careful to save it as a .csv with the right formatting, or pandas will complain. Check that a file is correctly formatted like so:
import pandas as pd
test=pd.read_csv("filename.csv")
testYou can also add new files for new instruments. Be sure to keep the file format and header names consistent.
You can create your own directory for .csv files. For example supposed you wanted to get your adjusted prices from
pysystemtrade/private/system_name/adjusted_price_data. Here is how you'd use it:
from sysdata.sim.csv_futures_sim_data import csvFuturesSimData
from systems.provided.futures_chapter15.basesystem import futures_system
data=csvFuturesSimData(csv_data_paths=dict(csvFuturesAdjustedPricesData = "private.system_name.adjusted_price_data"))
system=futures_system(data=data)Notice that we use python style "." internal references within a project, we don't give actual path names. See here for how to specify filenames in pysystemtrade.
The full list of keys that you can use in the csv_data_paths are:
csvFuturesInstrumentData(configuration and costs)csvFuturesMultiplePricesData(prices for current, next and carry contracts)csvFuturesAdjustedPricesData(stitched back-adjusted prices)csvFxPricesData(for FX prices)csvRollParametersData(for roll configuration)
Note that you can't put adjusted prices and carry data in the same directory since they use the same file format.
There is more detail about using .csv files here.
If you want to store your data in Mongo DB databases instead you need to use a different data object.
If you want to get your data from Quandl.com, then see the document working with futures data
If you want to get data from a different place (eg a database, yahoo finance, broker, quandl...) you'll need to create your own Data object.
If you want to use a different set of data values (eg equity EP ratios, interest rates...) you'll need to create your own Data object.
If you want to delve deeper into data storage see the document working with futures data
To remain organised it's good practice to save any work into a directory like
pysystemtrade/private/this_system_name/ (you'll need to create the
directory first). If you plan to contribute to github, just be careful to
avoid adding 'private' to your commit ( you may want to read
this
).
You can save the contents of a system cache to avoid having to redo calculations when you come to work on the system again (but you might want to read about system caching and pickling before you reload them).
from systems.provided.futures_chapter15.basesystem import futures_system
system = futures_system()
system.accounts.portfolio().sharpe() ## does a whole bunch of calculations that will be saved in the cache
system.cache.pickle("private.this_system_name.system.pck") ## use any file extension you like
## In a new session
from systems.provided.futures_chapter15.basesystem import futures_system
system = futures_system()
system.cache.unpickle("private.this_system_name.system.pck")
## this will run much faster and reuse previous calculations
# only complex accounting p&l objects aren't saved in the cache
system.accounts.portfolio().sharpe()You can also save a config object into a yaml file - see saving configuration.
The guide section explains in more detail how each part of the system works:
Each section is split into parts that get progressively trickier; varying from using the standard objects that are supplied up to writing your own.
A data object is used to feed data into a system. Data objects work with a particular kind of data (normally asset class specific, eg futures) from a particular source (for example .csv files, databases and so on).
Two kinds of specific data object is currently provided with the system in the
current version - csvFuturesSimData (.csv files) and dbFuturesSimData (database storage)
You can import and use data objects directly:
These commands will work with all data objects - the csvFuturesSimData version is
used as an example.
from sysdata.sim.csv_futures_sim_data import csvFuturesSimData
data=csvFuturesSimData()
## getting data out
data.methods() ## list of methods
data.get_raw_price(instrument_code)
data[instrument_code] ## does the same thing as get_raw_price
data.get_instrument_list()
data.keys() ## also gets the instrument list
data.get_value_of_block_price_move(instrument_code)
data.get_instrument_currency(instrument_code)
data.get_fx_for_instrument(instrument_code, base_currency) # get fx rate between instrument currency and base currencyOr within a system:
## using with a system
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(data=data)
system.data.get_instrument_currency(instrument_code) # and so on(Note that when specifying a data item within a trading rule you
should omit the system eg data.get_raw_price)
If you set the start_date configuration option, then only a subset of the data will be shown:
## using with a system
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(data=data)
# We could also do this in the .yaml file. Note the formatting used must be the same
system.config.start_date = '2000-01-19'
## or as a datetime (won't work in yaml obviously)
import datetime
system.config.start_date = datetime.datetime(2000,1,19)The csvFuturesSimData object works like this:
from sysdata.sim.csv_futures_sim_data import csvFuturesSimData
## with the default folders
data=csvFuturesSimData()
## OR with different folders, by providing a dict containing the folder(s) to use
data=csvFuturesSimData(csv_data_paths = dict(key_name = "pathtodata.with.dots"))
# Permissible key names are 'csvFxPricesData' (FX prices), 'csvFuturesMultiplePricesData'
# (for carry and forward prices),
# 'csvFuturesAdjustedPricesData' and 'csvFuturesInstrumentData' (configuration and costs).
# If a keyname is not present then the system defaults will be used
# An example to override with FX data stored in /psystemtrade/private/data/fxdata/:
data=csvFuturesSimData(csv_data_paths = dict(csvFxPricesData="private.data.fxdata"))
# WARNING: Do not store multiple_price_data and adjusted_price_data in the same directory
# They use the same file names!
## getting data out
data.methods() ## will list any extra methods
data.get_instrument_raw_carry_data(instrument_code) ## specific data for futures
## using with a system
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(data=data)
system.data.get_instrument_raw_carry_data(instrument_code)Each relevant pathname must contain .csv files of the following four types (where code is the instrument_code):
- Static configuration and cost data-
instrument_config.csvheadings: Instrument, Pointsize, AssetClass, Currency. Additional headings for costs: Slippage, PerBlock, Percentage, PerTrade. See 'costs' for more detail. - Roll parameters data. See storing futures and spot FX data for more detail.
- Adjusted price data-
code.csv(eg SP500.csv) headings: DATETIME, PRICE - Carry and forward data -
code.csv(eg AEX.csv): headings: DATETIME, PRICE,CARRY,FORWARD,CARRY_CONTRACT PRICE_CONTRACT, FORWARD_CONTRACT - Currency data -
ccy1ccy2fx.csv(eg AUDUSDfx.csv) headings: DATETIME, FXRATE
DATETIME should be something that pandas.to_datetime can parse. Note that the
price in (2) is the continuously stitched price (see volatility
calculation ), whereas the price column in (3) is the price of the
contract we're currently trading.
At a minimum we need to have a currency file for each instrument's currency
against the default (defined as "USD"); and for the currency of the account
we're trading in (i.e. for a UK investor you'd need a GBPUSDfx.csv file). If
cross rate files are available they will be used; otherwise the USD rates will
be used to work out implied cross rates.
See data in subdirectories pysystemtrade/data/futures for files you can modify:
For more information see the futures data document.
This is a simData object which gets it's data out of Mongo DB (static) and Arctic (time series) (Yes the class name should include both terms. Yes I shortened it so it isn't ridiculously long, and most of the interesting stuff comes from Arctic). It is better for live trading.
For production code, and storing large amounts of data (eg for individual futures contracts) we probably need something more robust than .csv files. MongoDB is a no-sql database which is rather fashionable at the moment, though the main reason I selected it for this purpose is that it is used by Arctic. Arctic is a superb open source time series database which sits on top of Mongo DB) and provides straightforward and fast storage of pandas DataFrames. It was created by my former colleagues at Man AHL (in fact I beta tested a very early version of Arctic), and then very generously released as open source.
There is more detail on this in the futures data documentation: Mongo DB and Arctic.
Obviously you will need to make sure you already have a Mongo DB instance running. You might find you already have one running, in Linux use ps wuax | grep mongo and then kill the relevant process. You also need to get Arctic.
Because the mongoDB data isn't included in the github repo, before using this you need to write the required data into Mongo and Arctic. You can do this from scratch, as per the 'futures data workflow'. Alternatively you can run the following scripts which will copy the data from the existing github .csv files:
Of course it's also possible to mix these two methods.
Once you have the data it's just a matter of replacing the default csv data object:
from systems.provided.futures_chapter15.basesystem import futures_system
from sysdata.sim.db_futures_sim_data import dbFuturesSimData
# with the default database
data = dbFuturesSimData()
# using with a system
system = futures_system()
print(system.accounts.portfolio().sharpe())You should be familiar with the python object orientated idiom before reading this section.
The simData() object is the base class for data used in simulations. From that we
inherit data type specific classes such as those
for futures object. These in turn are inherited from
for specific data sources, such as for csv files: csvFuturesSimData().
It is helpful if this naming scheme was adhered to: sourceTypeSimData. For example if we had
some single equity data stored in a database we'd do class EquitiesSimData(simData), and class dbEquitiesSimData(EquitiesSimData).
So, you should consider whether you need a new type of data, a new source of
data or both. You may also wish to extend an existing class. For example if you
wished to add some fundamental data for futures you might define: class fundamentalFuturesSimData(futuresSimData). You'd then need to inherit from that for a
specific source.
This might seem a hassle, and it's tempting to skip and just inherit from
simData() directly, however once your system is up and running it is very
convenient to have the possibility of multiple data sources and this process
ensures they keep a consistent API for a given data type.
It's worth reading the documentation on futures data to understand how csvFuturesSimData() is constructed before modifying it or creating your own data objects.
Methods that you'll probably want to override:
get_raw_priceReturns Tx1 pandas data frameget_instrument_listReturns list of strget_value_of_block_price_moveReturns floatget_raw_cost_dataReturns a dict cost dataget_instrument_currency: Returns str_get_fx_data(currency1, currency2)Returns Tx1 pandas data frame of exchange rates- 'get_rolls_per_year': returns int
You should not override get_fx_for_instrument, or any of the other private fx
related methods. Once you've created a _get_fx_data method, then the methods
in the Data base class will interact to give the correct fx rate when
external objects call get_fx_for_instrument(); handling cross rates and
working them out as needed.
Neither should you override 'daily_prices'.
Finally data methods should not do any caching. Caching is done within the system class.
Configuration (config) objects determine how a system behaves. Configuration
objects are very simple; they have attributes which contain either parameters,
or nested groups of parameters.
There are three main ways to create a configuration object:
- Interactively from a dictionary
- By pulling in a YAML file
- From a 'pre-baked' system
- By joining together multiple configurations in a list
from sysdata.config.configdata import Config
my_config_dict=dict(optionone=1, optiontwo=dict(a=3.0, b="beta", c=["a", "b"]), optionthree=[1.0, 2.0])
my_config=Config(my_config_dict)There are no restrictions on what is nested in the dictionary, but if you include arbitrary items like the above they won't be very useful!. The section on configuration options explains what configuration options would be used by a system.
This simple file will reproduce the useless config we get from a dictionary in the example above.
optionone: 1
optiontwo:
a: 3.0
b: "beta"
c:
- "a"
- "b"
optionthree:
- 1.0
- 2.0
Note that as with python the indentation in a yaml file shows how things are nested. If you want to learn more about yaml check this out.
from sysdata.config.configdata import Config
my_config=Config("private.filename.yaml") ## assuming the file is in "pysystemtrade/private/filename.yaml"See here for how to specify filenames in pysystemtrade.
In theory there are no restrictions on what is nested in the dictionary (but the top level must be a dict); although it is easier to use str, float, int, lists and dicts, and the standard project code only requires those (if you're a PyYAML expert you can do other python objects like tuples, but it won't be pretty).
You should respect the structure of the default config with respect to nesting, as otherwise the defaults won't be properly filled in.
The section on configuration options explains what configuration options are available.
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
new_config=system.configUnder the hood this is effectively getting a configuration from a .yaml file - this one.
Configs created in this way will include all the defaults populated.
We can also pass a list into Config(), where each item of the list contains a
dict or filename. For example we could do this with the simple filename example
above:
from sysdata.config.configdata import Config
my_config_dict=dict(optionfour=1, optionfive=dict(one=1, two=2.0))
my_config=Config(["filename.yaml", my_config_dict])Note that if there are overlapping keynames, then those in latter parts of the list of configs will override earlier versions.
This can be useful if, for example, we wanted to change the instrument weights 'on the fly' but keep the rest of the configuration unchanged.
Sometimes it is more convenient to specify certain parameters in a .csv file, then push them into a .yaml file. If you want to use this method then you can use these two functions:
from sysinit.configtools.csvweights_to_yaml import instr_weights_csv_to_yaml # for instrument weights
from sysinit.configtools.csvweights_to_yaml import forecast_weights_by_instrument_csv_to_yaml # forecast weights for each instrument
from sysinit.configtools.csvweights_to_yaml import forecast_mapping_csv_to_yaml # Forecast mapping for each instrumentThese will create .yaml files which can then be pasted into your existing configuration files.
Many (but not all) configuration parameters have defaults which are used by the system if the parameters are not in the object. These can be found in the defaults.yaml file. The section on configuration options explains what the defaults are, and where they are used.
I recommend that you do not change these defaults. It's better to use the settings you want in each system configuration file, or use a private configuration file if this is something you want to apply to all your backtests.
If this file exists, /private/private_config.yaml, it will be used as a private configuration file.
Basically, whenever a configuration object is added to a system, if there is a private config file then we add the elements from that. Then for any remaining missing elements we add the elements from the defaults.yaml.
In certain places you can change the function used to do a particular calculation, eg volatility estimation (This does not include trading rules - the way we change the functions for these is quite different). This is straightforward if you're going to use the same arguments as the original argument. However if you change the arguments you'll need to change the project defaults .yaml file. I recommend keeping the original parameters, and adding new ones with different names, to avoid accidentally breaking the system.
When added to a system the config class fills in parameters that are missing from the original config object, but are present in (i) the private .yaml file and (ii) the default .yaml file. For example if forecast_scalar is missing from the config, then the default value of 1.0 will be used. This works in a similar way for top level config items that are lists, str, int and float.
This will also happen if you miss anything from a dict within the config (eg if
config.forecast_div_mult_estimate is a dict, then any keys present in this
dict in the default .yaml, but not in the config will be added). Finally it
will work for nested dicts, eg if any keys are missing from
config.instrument_weight_estimate['correlation_estimate'] then they'll be filled
in from the default file. If something is a dict, or a nested dict, in the
config but not in the default (or vice versa) then values won't be replaced and
bad things could happen. It's better to keep your config files, and the default
file, with matching structures (for the items you want to change at least!). Again this is a good argument for adding new
parameters, and retaining the original ones.
Note this means that the config before, and after, it goes into a system object will probably be different; the latter will be populated with defaults.
from sysdata.config.configdata import Config
my_config=Config()
print(my_config) ## empty config Config with elements:
Now within a system:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(config=my_config)
print(system.config) ## full of defaults.
print(my_config) ## same object Config with elements: average_absolute_forecast, base_currency, buffer_method, buffer_size, buffer_trade_to_edge, forecast_cap, forecast_correlation_estimate, forecast_div_mult_estimate, forecast_div_multiplier, forecast_scalar, forecast_scalar_estimate, forecast_weight_estimate, instrument_correlation_estimate, instrument_div_mult_estimate, instrument_div_multiplier, instrument_weight_estimate, notional_trading_capital, percentage_vol_target, use_SR_costs, use_forecast_scale_estimates, use_forecast_weight_estimates, use_instrument_weight_estimates, volatility_calculation
Note this isn't enough for a working trading system as trading rules aren't populated by the defaults:
system.accounts.portfolio()# deleted full error trace
Exception: A system config needs to include trading_rules, unless rules are passed when object created
Regardless of whether we create the dictionary using a yaml file or interactively, we'll end up with a dictionary. The keys in the top level dictionary will become attributes of the config. We can then use dictionary keys or list positions to access any nested data. For example using the simple config above:
my_config.optionone
my_config.optiontwo['a']
my_config.optionthree[0]It's equally straightforward to modify a config. For example using the simple config above:
my_config.optionone=1.0
my_config.optiontwo['d']=5.0
my_config.optionthree.append(6.3)You can also add new top level configuration items:
my_config.optionfour=20.0
setattr(my_config, "optionfour", 20.0) ## if you preferOr remove them:
del(my_config.optionone)With real configs you need to be careful with nested parameters:
config.instrument_div_multiplier=1.1 ## not nested, no problem
## Heres an example of how you'd change a nested parameter
## If the element doesn't yet exist in your config
## If the element did exist, then obviously doing this would overwrite all other parameters in the config - so don't do it!
config.volatility_calculation=dict(days=20)
## If it does exist you can do this instead:
config.volatility_calculation['days']=20This is especially true if you're changing the config that has been included within a system, which will already include all the defaults:
system.config.instrument_div_multiplier=1.1 ## not nested, no problem
## If we change anything that is nested, we need to change just one element to avoid clearing the defaults:
# So, do this:
system.config.volatility_calculation['days']=20
# Do NOT do this:
# system.config.volatility_calculation=dict(days=20)Once we're happy with our configuration we can use it in a system:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system(config=my_config)Note it's only when a config is included in a system that the private configuration and defaults are populated.
If you develop your own stages or modify existing ones you might want to include new configuration options. Here's what your code should do:
## Assuming your config item is called my_config_item; in the relevant method:
parameter=system.config.my_config_item
## You can also use nested configuration items, eg dict keyed by instrument_code (or nested lists)
parameter=system.config.my_config_dict[instrument_code]
## Lists also work.
parameter=system.config.my_config_list[1]
## (Note: it's possible to do tuples, but the YAML is quite messy. So I don't encourage it.)
You would then need to add the following kind of thing to your config file:
my_config_item: "ni"
my_config_dict:
US10: 45.0
US5: 0.10
my_config_list:
- "first item"
- "second item"
Similarly if you wanted to use project defaults for your new parameters you'll also need to include them in the defaults.yaml file. Make sure you understand how the defaults work.
You can also save a config object into a yaml file:
from systems.provided.futures_chapter15.basesystem import futures_system
import yaml
from syscore.fileutils import resolve_path_and_filename_for_package
system = futures_system()
my_config = system.config
## make some changes to my_config here
filename = resolve_path_and_filename_for_package("private.this_system_name.config.yaml")
with open(filename, 'w') as outfile:
outfile.write(yaml.dump(my_config, default_flow_style=True))This is useful if you've been playing with a backtest configuration, and want to record the changes you've made. Note this will save trading rule functions as functions; this may not work and it will also be ugly. So you should use strings to define rule functions (see rules for more information)
You can also save the final optimised parameters into fixed weights for live trading:
# Assuming system already contains a system which has estimated values
from systems.diagoutput import systemDiag
sysdiag = systemDiag(system)
sysdiag.yaml_config_with_estimated_parameters('someyamlfile.yaml',
attr_names=['forecast_scalars',
'forecast_weights',
'forecast_div_multiplier',
'forecast_mapping',
'instrument_weights',
'instrument_div_multiplier'])Change the list of attr_names depending on what you want to output. You can then merge the resulting .yaml file into your simulated .yaml file. Don't forget to turn off the flags for use_forecast_div_mult_estimates,use_forecast_scale_estimates,use_forecast_weight_estimates,use_instrument_div_mult_estimates, and use_instrument_weight_estimates. You don't need to change flag for forecast mapping, since this isn't done by default.
It shouldn't be necessary to modify the configuration class since it's deliberately lightweight and flexible.
An instance of a system object consists of a number of stages, some data, and normally a config object.
We can create a system from an existing 'pre-baked system'. These include a ready made set of data, a list of stages, and a config.
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()We can override what's provided, and include our own data, and / or configuration, in such a system:
system=futures_system(data=my_data)
system=futures_system(config=my_config)
system=futures_system(data=my_data, config=my_config)Finally we can also create our own trading rules object, and pass that in. This is useful for interactive model development. If for example we've just written a new rule on the fly:
my_rules=dict(rule=a_new_rule)
system=futures_system(trading_rules=my_rules) ## we probably need a new configuration as well here if we're using fixed forecast weightsThis system implements the framework in chapter 15 of my book.
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()Effectively it implements the following;
data=csvFuturesSimData() ## or the data object that has been passed
config=Config("systems.provided.futures_chapter15.futuresconfig.yaml") ## or the config object that is passed
## Optionally the user can provide trading_rules (something which can be parsed as a set of trading rules); however this defaults to None in which case
## the rules in the config will be used.
system=System([Account(), Portfolios(), PositionSizing(), RawData(), ForecastCombine(),
ForecastScaleCap(), Rules(trading_rules)], data, config)This system implements the framework in chapter 15 of my book, but includes estimation of forecast scalars, instrument and forecast diversification multiplier, instrument and forecast weights.
from systems.provided.futures_chapter15.estimatedsystem import futures_system
system=futures_system()Effectively it implements the following;
data=csvFuturesSimData() ## or the data object that has been passed
config=Config("systems.provided.futures_chapter15.futuresestimateconfig.yaml") ## or the config object that is passed
## Optionally the user can provide trading_rules (something which can be parsed as a set of trading rules); however this defaults to None in which case
## the rules in the config will be used.
system=System([Account(), Portfolios(), PositionSizing(), RawData(), ForecastCombine(),
ForecastScaleCap(), Rules(trading_rules)], data, config)The key configuration differences from the standard system are that the estimation parameters:
use_forecast_scale_estimatesuse_forecast_weight_estimatesuse_instrument_weight_estimatesuse_forecast_div_mult_estimatesuse_instrument_div_mult_estimates
... are all set to True.
Warning: Be careful about changing a system from estimated to non estimated 'on the fly' by varying the estimation parameters (in the form use_*_estimates). See persistence of 'switched' stage objects for more information.
The system object doesn't do very much in itself, except provide access to its 'child' stages, its cache, and a limited number of methods. The child stages are all attributes of the parent system.
For example to get the final portfolio level 'notional' position, which is in
the child stage named portfolio:
system.portfolio.get_notional_position("EDOLLAR")We can also access the methods in the data object that is part of every system:
system.data.get_raw_price("EDOLLAR")For a list of all the methods in a system and its stages see stage methods. Alternatively:
system ## lists all the stages
system.accounts.methods() ## lists all the methods in a particular stage
system.data.methods() ## also works for dataWe can also access or change elements of the config object:
system.config.trading_rules
system.config.instrument_div_multiplier=1.2The base system only has a public few methods of it's own (apart from those used for caching, described below):
system.get_instrument_list() This will get the list of instruments in the
system, either from the config object if it contains instrument weights, or
from the data object.
These methods also get lists of instruments, see instrument documentation for more.
get_list_of_bad_markets
get_list_of_markets_not_trading_but_with_data
get_list_of_duplicate_instruments_to_remove
get_list_of_ignored_instruments_to_remove
get_list_of_instruments_to_remove
get_list_of_markets_with_trading_restrictions'
system.log provides access to the system's log. See logging for more
details.
Pulling in data and calculating all the various stages in a system can be a
time consuming process. So the code supports caching. When we first ask for
some data by calling a stage method, like
system.portfolio.get_notional_position("EDOLLAR"), the system first checks to
see if it has already pre-calculated this figure. If not then it will calculate
the figure from scratch. This in turn may involve calculating preliminary
figures that are needed for this position, unless they've already been
pre-calculated. So for example to get a combined forecast, we'd already need to
have all the individual forecasts from different trading rule variations for a
particular instrument. Once we've calculated a particular data point, which
could take some time, it is stored in the system object cache (along with any
intermediate results we also calculated). The next time we ask for it will be
served up immediately.
Most of the time you shouldn't need to worry about caching. If you're testing different configurations, or updating or changing your data, you just have to make sure you recreate the system object from scratch after each change. A new system object will have an empty cache.
Cache labels
from copy import copy
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.combForecast.get_combined_forecast("EDOLLAR")
## What's in the cache?
system.cache.get_cache_refs_for_instrument("EDOLLAR")
[_get_forecast_scalar_fixed in forecastScaleCap for instrument EDOLLAR [carry] , get_raw_forecast in rules for instrument EDOLLAR [ewmac32_128] ...
## Let's make a change to the config:
system.config.forecast_div_multiplier=0.1
## This will produce the same result, as we've cached the result
system.combForecast.get_combined_forecast("EDOLLAR")
## but if we make a new system with the new config...
system=futures_system(config=system.config)
## check the cache is empty:
system.cache.get_cache_refs_for_instrument("EDOLLAR")
## ... we get a different result
system.combForecast.get_combined_forecast("EDOLLAR")
## We can also turn caching off
## First clear the cache
system.cache.clear()
## ... should be nothing here
system.cache.get_cache_refs_for_instrument("EDOLLAR")
## Now turn off caching
system.cache.set_caching_off()
## Now after getting some data:
system.combForecast.get_combined_forecast("EDOLLAR")
##.... the cache is still empty
system.cache.get_cache_refs_for_instrument("EDOLLAR")
## if we change the config
system.config.forecast_div_multiplier=100.0
## ... then the result will be different without needing to create a new system
system.combForecast.get_combined_forecast("EDOLLAR")It can take a while to backtest a large system. It's quite useful to be able to save the contents of the cache and reload it later. I use the python pickle module to do this.
For boring python related reasons not all elements in the cache will be saved. The accounting information, and the optimisation functions used when estimating weights, will be excluded and won't be reloaded.
from systems.provided.futures_chapter15.basesystem import futures_system
system = futures_system()
system.accounts.portfolio().sharpe() ## does a whole bunch of calculations that will be saved in the cache. A bit slow...
system.cache.get_itemnames_for_stage("accounts") # includes 'portfolio'
# if I asked for this again, it's superfast
system.accounts.portfolio().sharpe()
## save it down
system.cache.pickle("private.this_system_name.system.pck") ## Using the 'dot' method to identify files in the workspace. use any file extension you like
## Now in a new session
system = futures_system()
system.cache.get_items_with_data() ## check empty cache
system.cache.unpickle("private.this_system_name.system.pck")
system.cache.get_items_with_data() ## Cache is now populated. Any existing data in system instance would have been removed.
system.get_itemnames_for_stage("accounts") ## now doesn't include ('accounts', 'portfolio', 'percentageTdelayfillTroundpositionsT')
system.accounts.portfolio().sharpe() ## Not coming from the cache, but this will run much faster and reuse many previous calculationsSee here for how to specify filenames in pysystemtrade.
It's also possible to selectively delete certain cached items, whilst keeping the rest of the system intact. You shouldn't do this without understanding stage wiring. You need to have a good knowledge of the various methods in each stage, to understand the downstream implications of either deleting or keeping a particular data value.
There are four attributes of data stored in the cache:
- Unprotected data that is deleted from the cache on request
- Protected data that wouldn't normally be deletable. Outputs of lengthy estimations are usually protected
- Data specific to a particular instrument (can be protected or unprotected)
- Data which applies to the whole system; or at least to multiple instruments (can be protected or unprotected)
Protected items and items common across the system wouldn't normally be deleted since they are usually the slowest things to calculate.
For example here are is how we'd check the cache after getting a notional position (which generates a huge number of intermediate results). Notice the way we can filter and process lists of cache keys.
system.portfolio.get_notional_position("EDOLLAR")
system.cache.get_items_with_data() ## this list everything.
system.cache.get_cacherefs_for_stage("portfolio") ## lists everything in a particular stage
system.cache.get_items_with_data().filter_by_stage_name("portfolio") ## more idiomatic way
system.cache._get_protected_items() ## lists protected items
system.cache.get_items_with_data().filter_by_instrument_code("EDOLLAR") ## list items with data for an instrument
system.cache.get_cache_refs_across_system() ## list items that run across the whole system or multiple instruments
system.cache.get_items_with_data().filter_by_itemname('get_capped_forecast').unique_list_of_instrument_codes() ## lists all instruments with a capped forecastNow if we want to selectively clear parts of the cache we could do one of the following:
system.cache.delete_items_for_instrument(instrument_code) ## deletes everything related to an instrument: NOT protected, or across system items
system.cache.delete_items_across_system() ## deletes everything that runs across the system; NOT protected, or instrument specific items
system.cache.delete_all_items() ## deletes all items relating to an instrument or across the system; NOT protected
system.cache.delete_items_for_stage(stagename) ## deletes all items in a particular stage, NOT protected
## Be careful with these:
system.cache.delete_items_for_instrument(instrument_code, delete_protected=True) ## deletes everything related to an instrument including protected; NOT across system items
system.cache.delete_items_across_system(delete_protected=True) ## deletes everything including protected items that runs across the system; NOT instrument specific items
## If you run these you will empty the cache completely:
system.cache.delete_item(itemname) ## delete everything in the cache for a paticluar item - including protected and across system items
system.cache.delete_all_items(delete_protected=True) ## deletes all items relating to an instrument or across the system - including protected items
system.cache.delete_items_for_stage(stagename, delete_protected=True) ## deletes all items in a particular stage - including protected items
system.cache.clear()Creating a new system might be very slow. For example estimating the forecast scalars, and instrument and forecast weights from scratch will take time, especially if you're bootstrapping. For this reason they're protected from cache deletion.
A possible workflow might be:
- Create a basic version of the system, with all the instruments and trading rules that you need.
- Run a backtest. This will optimise the instrument and forecast weights, and estimate forecast scalars (to really speed things up here you could use a faster method like shrinkage. See the section on optimisation for more information.).
- Change and modify the system as desired. Make sure you change the config object that is embedded within the system. Don't create a new system object.
- After each change, run
system.delete_all_items()before backtesting the system again. Anything that is protected won't be re-estimated, speeding up the process. - Back to step 3, until you're happy with the results (but beware of implicit overfitting!)
- run
system.delete_all_items(delete_protected=True)or equivalently create a new system object - Run a backtest. This will re-estimate everything from scratch for the final version of your system.
Another reason to use caching would be if you want to do your initial exploration with just a subset of the data.
- Create a basic version of the system, with a subset of the instruments and trading rules that you need.
- .... 6 as before
- Add the rest of your instruments to your data set.
- Run a backtest. This will re-estimate everything from scratch for the final version of your system, including the expanded instrument weights.
Here's a simple example of using caching in system development:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
# step 2
system.accounts.portfolio().curve() ## effectively runs an entire backtest
# step 3
new_idm=1.1 ## new IDM
system.config.instrument_div_multiplier=new_idm
# step 4
system.cache.delete_all_items() ## protected items won't be affected
system.accounts.portfolio().curve() ## re-run the backtest
# Assuming we're happy- move on to step 6
system.cache.delete_all_items(delete_protected=True)
## or alternatively recreate the system using the modified config:
new_config=system.config
system=futures_system(config=new_config)
## Step 7
system.accounts.portfolio().curve() ## re-run the final backtestAlthough the project doesn't yet include a live trading system, the caching behaviour of the system object will make it more suitable for a live system. If we're trading slowly enough, eg every day, we might be want to to do this overnight:
- Get new prices for all instruments
- Save these in wherever our data object is looking
- Create a new system object from scratch
- Run the system by asking for optimal positions for all instruments
Step 4 might be very involved and slow, but markets are closed so that's fine.
Then we do the following throughout the day:
- Wait for a new price to come in (perhaps through a message bus)
- So we don't subsequently use stale prices delete everything specific to that
instrument with
system.delete_items_for_instrument(instrument_code) - Re-calculate the optimal positions for this instrument
- This is then passed to our trading algo
Because we've deleted everything specific to the instrument we'll recalculate the positions, and all intermediate stages, using the new price. However we won't have to repeat lengthy calculations that cut across instruments, such as correlation estimates, risk overlays, cross sectional data or weight estimation. That can wait till our next overnight run.
If you're going to write new methods for stages (or a complete new stage) you need to follow some rules to keep caching behaviour consistent.
The golden rule is a particular value should only be cached once, in a single place.
So the data object methods should never cache; they should just behave like 'pipes' passing data through to system stages on request. This saves the hassle of having to write methods which delete items in the data object cache as well as the system cache.
Similarly most stages contain 'input' methods, which do no calculations but get the 'output' from an earlier stage and then 'serve' it to the rest of the stage. These exist to simplify changing the internal wiring of a stage and reduce the coupling between methods from different stages. These should also never cache; or again we'll be caching the same data multiple times ( see stage wiring ).
You should cache as early as possible; so that all the subsequent stages that need that data item already have it. Avoid looping back, where a stage uses data from a later stage, as you may end up with infinite recursion.
The cache 'lives' in the parent system object in the attribute system.cache,
not the stage with the relevant method. There are standard functions which
will check to see if an item is cached in the system, and then call a function
to calculate it if required (see below). To make this easier when a stage
object joins a system it gains an attribute self.parent, which will be the
'parent' system.
Think carefully about whether your method should create data that is protected from casual cache deletion. As a rule anything that cuts across instruments and / or changes slowly should be protected. Here are the current list of protected items:
- Estimated Forecast scalars
- Estimated Forecast weights
- Estimated Forecast diversification multiplier
- Estimated Forecast correlations
- Estimated Instrument diversification multiplier
- Estimated Instrument weights
- Estimated Instrument correlations
To this list I'd add any cross sectional data, and anything that measures portfolio risk (not yet implemented in this project).
Also think about whether you're going to cache any complex objects that
pickle might have trouble with, like class instances. You need to flag these
up as problematic.
Caching is implemented (as of version 0.14.0 of this project) by python decorators attached to methods in the stage objects. There are four decorators used by the code:
@input- no caching done, input method see stage wiring@dont_cache- no caching done, used for very trivial calculations that aren't worth caching@diagnostic()- caching done within the body of a stage@output()- caching done producing an output
Notice the latter two decorators are always used with brackets, the former
without. Labelling your code with the @input or @dont_cache decorators has
no effect whatsoever, and is purely a labelling convention.
Similarly the @diagnostic and @output decorators perform exactly the same
way; it's just helpful to label your stage wiring and make
output functions clear.
The latter two decorators take two optional keyword arguments which default to
False @diagnostic(protected=False, not_pickable=False). Set protected=True
if you want to stop casual deletion of the results of a method. Set
not_pickable=True if the results of a method will be a complex nested object
that pickle will struggle with.
Here are some fragments of code from the forecast_combine.py file showing cache decorators in use:
@dont_cache
def _use_estimated_weights(self):
return str2Bool(self.parent.config.use_forecast_weight_estimates)
@dont_cache
def _use_estimated_div_mult(self):
# very simple
return str2Bool(self.parent.config.use_forecast_div_mult_estimates)
@input
def get_forecast_cap(self):
"""
Get the forecast cap from the previous module
:returns: float
KEY INPUT
"""
return self.parent.forecastScaleCap.get_forecast_cap()
@diagnostic()
def get_trading_rule_list_estimated_weights(self, instrument_code):
# snip
@diagnostic(protected=True, not_pickable=True)
def get_forecast_correlation_matrices_from_code_list(self, codes_to_use):
# snipIt's worth creating a new pre-baked system if you're likely to want to repeat a backtest, or when you've settled on a system you want to paper or live trade.
The elements of a new pre-baked system will be:
- New stages, or a different choice of existing stages.
- A set of data (either new or existing)
- A configuration file
- A python function that loads the above elements, and returns a system object
To remain organised it's good practice to save your configuration file and any
python functions you need into a directory like
pysystemtrade/private/this_system_name/ (you'll need to create a couple of
directories first). If you plan to contribute to github, just be careful to
avoid adding 'private' to your commit ( you may want to read
this
). If you have novel data you're using for this system, you may also want to
save it in the same directory.
Then it's a case of creating the python function. Here is an extract from the futuressystem for chapter 15
## We probably need these to get our data
from sysdata.sim.csv_futures_sim_data import csvFuturesSimData
from sysdata.config.configdata import Config
## We now import all the stages we need
from systems.forecasting import Rules
from systems.basesystem import System
from systems.forecast_combine import ForecastCombine
from systems.forecast_scale_cap import ForecastScaleCap
from systems.rawdata import RawData
from systems.positionsizing import PositionSizing
from systems.portfolio import Portfolios
from systems.accounts.accounts_stage import Account
def futures_system(data=None, config=None, trading_rules=None):
if data is None:
data = csvFuturesSimData()
if config is None:
config = Config("systems.provided.futures_chapter15.futuresconfig.yaml")
## It's nice to keep the option to dynamically load trading rules but if you prefer you can remove this and set rules=Rules() here
rules = Rules(trading_rules)
## build the system
system = System([Account(), Portfolios(), PositionSizing(), RawData(), ForecastCombine(),
ForecastScaleCap(), rules], data, config)
return systemIt shouldn't be necessary to modify the System() class or create new ones.
A stage within a system does part of the multiple steps of calculation that are needed to ultimately come up with the optimal positions, and hence the account curve, for the system. So the backtesting or live trading process effectively happens within the stage objects.
We define the stages in a system when we create it, by passing a list of stage objects as the first argument:
from systems.forecasting import Rules
from systems.basesystem import System
data=None ## this won't do anything useful
my_system=System([Rules()], data)(This step is often hidden when we use 'pre-baked' systems)
We can see what stages are in a system just by printing it:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
systemSystem with stages: accounts, portfolio, positionSize, rawdata, combForecast, forecastScaleCap, rules
Stages are attributes of the main system:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.rawdataSystemStage 'rawdata'
So we can access the data methods of each stage:
system.rawdata.get_raw_price("EDOLLAR").tail(5) price
2015-04-16 97.9350
2015-04-17 97.9400
2015-04-20 97.9250
2015-04-21 97.9050
2015-04-22 97.8325
system.rawdata.log provides access to the log for the stage rawdata, and so
on. See logging for more details.
It's worth having a basic understanding of how the stages within a system are 'wired' together. Furthermore if you're going to modify or create new code, or use advanced system caching, you're going to need to understand this properly.
What actually happens when we call
system.combForecast.get_combined_forecast("EDOLLAR") in the pre-baked futures
system? Well this in turn will call other methods in this stage, and they will
call methods in previous stages,.. and so on until we get back to the
underlying data. We can represent this with a diagram:
system.combForecast.get_combined_forecast("EDOLLAR")system.combForecast.get_forecast_diversification_multiplier("EDOLLAR")system.combForecast.get_forecast_weights("EDOLLAR")system.combForecast.get_capped_forecast("EDOLLAR", "ewmac2_8"))etcsystem.forecastScaleCap.get_capped_forecast("EDOLLAR", "ewmac2_8"))etcsystem.forecastScaleCap.get_forecast_cap("EDOLLAR", "ewmac2_8")etcsystem.forecastScaleCap.get_scaled_forecast("EDOLLAR", "ewmac2_8")etcsystem.forecastScaleCap.get_forecast_scalar("EDOLLAR", "ewmac2_8")etcsystem.forecastScaleCap.get_raw_forecast("EDOLLAR", "ewmac2_8")etcsystem.rules.get_raw_forecast("EDOLLAR", "ewmac2_8")etcsystem.data.get_raw_price("EDOLLAR")system.rawdata.get_daily_returns_volatility("EDOLLAR")- (further stages to calculate volatility omitted)
A system effectively consists of a 'tree' of which the above shows only a small part. When we ask for a particular 'leaf' of the tree, the data travels up the 'branches' of the tree, being cached as it goes.
The stage 'wiring' is how the various stages communicate with each other. Generally a stage will consist of:
- Input methods that get data from another stage without doing any further calculation
- Internal diagnostic methods that do intermediate calculations within a stage (these may be private, but are usually left exposed so they can be used for diagnostic purposes)
- Output methods that other stages will use for their inputs.
For example consider the first few items in the list above. Let's label them appropriately:
- Output (combForecast):
system.combForecast.get_combined_forecast("EDOLLAR")- Internal (combForecast):
system.combForecast.get_forecast_diversification_multiplier("EDOLLAR") - Internal (combForecast):
system.combForecast.get_forecast_weights("EDOLLAR") - Input (combForecast):
system.combForecast.get_capped_forecast("EDOLLAR", "ewmac2_8"))etc- Output (forecastScaleCap):
system.forecastScaleCap.get_capped_forecast("EDOLLAR", "ewmac2_8"))etc
- Output (forecastScaleCap):
- Internal (combForecast):
This approach (which you can also think of as the stage "API") is used to make it easier to modify the code - we can change the way a stage works internally, or replace it with a new stage with the same name, but as long as we keep the output method intact we don't need to mess around with any other stage.
If you're going to write a new stage (completely new, or to replace an existing stage) you need to keep the following in mind:
- New stages should inherit from
SystemStage - Modified stages should inherit from the existing stage you're modifying. For
example if you create a new way of calculating forecast weights then you
should inherit from class
ForecastCombine, and then override theget_forecast_weightsmethod; whilst keeping the other methods unchanged. - Completely new stages will need a unique name; this is specified in the
object method
_name(). They can then be accessed withsystem.stage_name - Modified stages should use the same name as their parent, or the wiring will go haywire.
- Think about whether you need to protect part of the system cache for this stage output system caching from casual deletion.
- Similarly if you're going to cache complex objects that won't pickle easily
(like accountCurve objects) you need to put a
not_pickable=Truein the decorator call. - Use non-cached input methods to get data from other stages. Be wary of accessing internal methods in other stages; try to stick to output methods only.
- Use cached input methods to get data from the system data object (since this is the first time it will be cached). Again only access public methods of the system data object.
- Use cached methods for internal diagnostic and output methods(see system caching ).
- If you want to store attributes within a stage, then prefix them with _ and include a method to access or change them. Otherwise the methods() method will return attributes as well as methods.
- Internal methods should be public if they could be used for diagnostics, otherwise prefix them with _ to make them private.
- The doc string for input and output methods should clearly identify them as such. This is to make viewing the wiring easier.
- The doc string at the head of the stage should specify the input methods (and where they take their input from), and the output methods
- The doc string should also explain what the stage does, and the name of the stage
- Really big stages should be separated across multiple classes (and possibly files), using multiple inheritance to glue them together. See the accounts stage for an example.
New stage code should be included in a subdirectory of the systems package (as for futures raw data ) or in your private directory.
The standard list of stages is as follows. The default class is given below, as well as the system attribute used to access the stage.
- Raw data: class RawData
system.rawdata - Forecasting: class Rules
system.rules(chapter 7 of my book) - Scale and cap forecasts: class
ForecastScaleCap
system.forecastScaleCap(chapter 7) - Combine forecasts: class
ForecastCombine
system.combForecast(chapter 8) - Calculate subsystem positions: class
PositionSizing
system.positionSize(chapters 9 and 10) - Create a portfolio across multiple instruments: class
Portfolios
system.portfolio(chapter 11) - Calculate performance: class
Account
system.accounts
Each of these stages is described in more detail below.
The raw data stage is used to pre-process data for calculating trading rules, scaling positions, or anything else we might need. Good reasons to include something in raw data are:
- If it is used multiple times, eg price volatility
- To provide better diagnostics and visibility in the system, eg the intermediate steps required to calculate the carry rule for futures
Using the standard RawData class
The base RawData class includes methods to get instrument prices, daily returns, volatility, and normalised returns (return over volatility).
As we are trading futures the raw data class has some extra methods needed to calculate the carry rule for futures, and to expose the intermediate calculations.
(Versions prior to 1.06 had a separate FuturesRawData class)
There are two types of volatility in my trading systems:
- Price difference volatility eg sigma (Pt - Pt-1)
- Percentage return volatility eg sigma (Pt - Pt -1 / P*t-1)
The first kind is used in trading rules to normalise the forecast into something proportional to Sharpe Ratio. The second kind is used to scale positions. In both cases we use a 'stitched' price to work out price differences. So in futures we splice together futures contracts as we roll, shifting them according to the Panama method. Similarly if the system dealt with cash equities, it would handle ex-dividend dates in the same way. If we didn't do this, but just used the 'natural' price (the raw price of the contract we're trading) to calculate returns, we'd get sharp returns on rolls.
In fact stitched prices are used by default in the system; since they make more sense for trading rules that usually prefer smoother prices without weird jumps. Nearly all the methods in raw data that mention price are referring to the stitched price.
However when working out percentage returns we absolutely don't want to use the 'stitched' price as the denominator. For positive carry assets stitched prices will increase over time; this means they will be small or even negative in the past and the percentage returns will be large or have the wrong sign.
For this reason there is a special method in the data class called
daily_denominator_price. This tells the code what price to use for the P* in
the calculation above. As we are trading futures this uses the raw price of the
current contract.
The other point to note is that the price difference volatility calculation is
configurable through config.volatility_calculation.
The default function used is a robust EWMA volatility calculator with the following configurable attributes:
- 35 day span
- Needs 10 periods to generate a value
- Will floor any values less than 0.0000000001
- Applies a further vol floor which:
- Calculates the 5% percentile of vol using a 500 day moving average (needing 100 periods to generate a value)
- Floors any vol below that level
YAML:
volatility_calculation:
func: "sysquant.estimators.vol.robust_vol_calc"
days: 35
min_periods: 10
vol_abs_min: 0.0000000001
vol_floor: True
floor_min_quant: 0.05
floor_min_periods: 100
floor_days: 500
If you're considering using your own function please see configuring defaults for your own functions
It would make sense to create new raw data classes for new types of assets, or to get more visibility inside trading rule calculations.
For example:
- To work out the quality factor for an equity value system, based on raw accounting ratios
- To work out the moving averages to be used in an EWMAC trading rule, so they can be viewed for diagnostic purposes.
For new asset classes in particular you should think hard about what you should
override the daily_denominator_price (see discussion on volatility
calculation above).
Trading rules are at the heart of a fully systematic trading system. This stage description is different from the others; and will be in the form of a tutorial around creating trading rules.
The base class, Rules() is here; and it shouldn't be necessary to modify this class.
A trading rule consists of:
- a function
- some data (specified as positional arguments)
- some optional control arguments (specified as key word arguments)
So the function must be something like these:
def trading_rule_function(data1):
## do something with data1
def trading_rule_function(data1, arg1=default_value):
## do something with data1
## controlled by value of arg1
def trading_rule_function(data1, data2):
## do something with data1 and data2
def trading_rule_function(data1, data2, arg1=default_value, arg2=default_value):
## do something with data1
## controlled by value of arg1 and arg2... and so on.
At a minimum we need to know the function, since other arguments are optional, and if no data is specified the instrument price is used. A rule specified with only the function is a 'bare' rule. It should take only one data argument which is price, and have no other arguments that need new parameter values.
In this project there is a specific TradingRule
class. A TradingRule instance contains 3 elements -
a function, a list of any data the function needs, and a dict of any other
arguments that can be passed to the function.
The function can either be the actual function, or a relative reference to it
eg systems.provided.futures_chapter15.rules.ewmac (this is useful when a
configuration is created from a file). Data must always be in the form of
references to attributes and methods of the system object, eg
data.daily_prices or rawdata.get_daily_prices. Either a single data item,
or a list must be passed. Other arguments are in the form a dictionary.
We can create trading rules in a number of different ways. I've noticed that different people find different ways of defining rules more natural than others, hence the deliberate flexibility here.
Bare rules which only consist of a function can be defined as follows:
from systems.trading_rules import TradingRule
TradingRule(ewmac) ## with the actual function
TradingRule("systems.provided.futures_chapter15.rules.ewmac") ## string reference to the functionWe can also add data and other arguments. Data is always a list of str, or a single str. Other arguments are always a dict.
TradingRule(ewmac, data='rawdata.get_daily_prices', other_args=dict(Lfast=2, Lslow=8))Multiple data is fine, and it's okay to omit data or other_args:
TradingRule(some_rule, data=['rawdata.get_daily_prices','data.get_raw_price'])Sometimes it's easier to specify the rule 'en bloc'. You can do this with a 3 tuple. Notice here we're specifying the function with a string, and listing multiple data items:
TradingRule(("systems.provided.futures_chapter15.rules.ewmac", ['rawdata.get_daily_prices','data.get_raw_price'], dict(Lfast=3, Lslow=12)))You can also specify rules with a dict. If using a dict keywords can be omitted
(but not function).
TradingRule(dict(function="systems.provided.futures_chapter15.rules.ewmac", data=['rawdata.get_daily_prices','data.get_raw_price']))Note if you use an 'en bloc' method, and also include the data or
other_args arguments in your call to TradingRule, you'll get a warning.
The dictionary method is used when configuration objects are read from YAML files; these contain the trading rules in a nested dict.
YAML: (example)
trading_rules:
ewmac2_8:
function: systems.futures.rules.ewmac
data:
- "data.daily_prices"
- "rawdata.daily_returns_volatility"
other_args:
Lfast: 2
Lslow: 8
forecast_scalar: 10.6
Note that forecast_scalar isn't strictly part of the trading rule
definition, but if included here will be used instead of the separate
config.forecast_scalar parameter (see the next stage ).
All the items in the data list passed to a trading rule are string references to methods in the system object that (usually) take a single argument, the instrument code. In theory these could be anywhere in the system object, but by convention they should only be in system.rawdata or system.data (if they are in stages that call the rules stage, you will get infinite recursion and things will break), with perhaps occasional reference to system.get_instrument_list(). The advantage of using methods in rawdata is that these are cached, and can be re-used. It's strongly recommended that you use methods in rawdata for trading rules.
What if you want to pass arguments to the data method? For example, you might want to pre-calculate the moving averages of different lengths in rawdata and then reuse them to save time. Or you might want to calculate skew over a given time period for all markets and then take a cross sectional average to use in a relative value rule.
We can do this by passing special kinds of other_args which are pre-fixed with underscores, eg "_". If an element in the other_ags dictionary has no underscores, then it is passed to the trading rule function as a keyword argument. If it has one leading underscore eg "_argname", then it is passed to the first method in the data list as a keyword argument. If it has two underscores eg "__argname", then it is passed to the second method in the data list, and so on.
Let's see how we could implement the moving average example:
from systems.provided.futures_chapter15.basesystem import *
from systems.trading_rules import TradingRule
data = csvFuturesSimData()
config = Config(
"systems.provided.futures_chapter15.futuresconfig.yaml")
# First let's add a new method to our rawdata
# As well as the usual instrument_code this has a keyword argument, span, which we are going to access in our trading rule definitions
class newRawData(RawData):
def moving_average(self, instrument_code, span=8):
price = self.get_daily_prices(instrument_code)
return price.ewm(span=span).mean()
# Now for our new trading rule. Multiplier is a trivial variable, included to show you can mix other arguments and data arguments
def new_ewma(fast_ewma, slow_ewma, vol, multiplier=1):
raw_ewmac = fast_ewma - slow_ewma
raw_ewmac = raw_ewmac * multiplier
return raw_ewmac / vol.ffill()
# Now we define our first trading rule. Notice that data gets two kinds of moving average, but the first one will have span 2 and the second span 8
trading_rule1 = TradingRule(dict(function=new_ewma, data=['rawdata.moving_average', 'rawdata.moving_average',
'rawdata.daily_returns_volatility'],
other_args=dict(_span=2, __span=8, multiplier=1)))
# The second trading rule reuses one of the ewma, but uses a default value for the multiplier and the first ewma span (not great practice, but illustrates what is possible)
trading_rule2 = TradingRule(dict(function=new_ewma, data=['rawdata.moving_average', 'rawdata.moving_average',
'rawdata.daily_returns_volatility'],
other_args=dict(__span=32)))
rules = Rules(dict(ewmac2_8=trading_rule1, ewmac8_32=trading_rule2))
system = System([
Account(), Portfolios(), PositionSizing(), newRawData(),
ForecastCombine(), ForecastScaleCap(), rules
], data, config)
# This will now work in the usual way
system.rules.get_raw_forecast("EDOLLAR", "ewmac8_32")
system.rules.get_raw_forecast("EDOLLAR", "ewmac2_8")Notes: methods passed as data pointers must only have a single argument plus optionally keyword arguments. Multiple non keyword arguments will break. Also in specifying the other arguments you don't have to provide keyword arguments for all data elements, or for the trading rule: all are optional.
We can pass a trading rule, or a group of rules, into the class Rules() in a number of ways.
Normally we'd pass in the list of rules form a configuration object. Let's have a look at an incomplete version of the pre-baked chapter 15 futures system.
## We probably need these to get our data
from sysdata.sim.csv_futures_sim_data import csvFuturesSimData
from sysdata.config.configdata import Config
from systems.basesystem import System
## We now import all the stages we need
from systems.forecasting import Rules
from systems.rawdata import RawData
data=csvFuturesSimData()
config=Config("systems.provided.futures_chapter15.futuresconfig.yaml")
rules=Rules()
## build the system
system=System([rules, RawData()], data, config)
rules<snip>
Exception: A Rules stage needs to be part of a System to identify trading rules, unless rules are passed when object created
## Once part of a system we can see the rules
forecast=system.rules.get_raw_forecast('EDOLLAR','ewmac2_8')
rulesRules object with rules ewmac32_128, ewmac64_256, ewmac16_64, ewmac8_32, ewmac4_16, ewmac2_8, carry
##
rules.trading_rules(){'carry': TradingRule; function: <function carry at 0xb2e0f26c>, data: rawdata.daily_annualised_roll, rawdata.daily_returns_volatility and other_args: smooth_days,
'ewmac16_64': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow,
'ewmac2_8': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow,
'ewmac32_128': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow,
'ewmac4_16': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow,
'ewmac64_256': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow,
'ewmac8_32': TradingRule; function: <function ewmac at 0xb2e0f224>, data: rawdata.daily_prices, rawdata.daily_returns_volatility and other_args: Lfast, Lslow}
What actually happens when we run this? (this is a little complex but worth understanding).
- The
Rulesclass is created with no arguments. - When the
Rulesobject is first created it is 'empty' - it doesn't have a list of valid processed trading rules. - We create the
systemobject. This means that all the stages can see the system, in particular they can see the configuration get_raw_forecastis called, and looks for the trading rule "ewmac2_8". It gets this by calling the methodget_trading_rules- When the method
get_trading_rulesis called it looks to see if there is a processed dict of trading rules - The first time the method
get_trading_rulesis called there won't be a processed list. So it looks for something to process - First it will look to see if anything was passed when the instance rules of the
Rules()class was created - Since we didn't pass anything instead it processes what it finds in
system.config.trading_rules- a nested dict, keynames rule variation names. - The
Rulesinstance now has processed rule names in the form of a dict, keynames rule variation names, each element containing a validTradingRuleobject
Often when we're working in development mode we won't have worked up a proper
config. To get round this we can pass a single trading rule or a set of trading
rules to the Rules() instance when we create it. If we pass a dict, then the
rules will be given appropriate names, otherwise if a single rule or a list is
passed they will be given arbitrary names "rule0", "rule1", ...
Also note that we don't have pass a single rule, list or dict of rules; we can also pass anything that can be processed into a trading rule.
## We now import all the stages we need
from systems.forecasting import Rules
## Pass a single rule. Any of the following are fine. See 'Trading rules' for more.
trading_rule=TradingRule(ewmac)
trading_rule=(ewmac, 'rawdata.get_daily_prices', dict(Lfast=2, Lslow=8))
trading_rule=dict(function=ewmac, data='rawdata.get_daily_prices', other_args=dict(Lfast=2, Lslow=8))
rules=Rules(trading_rule)
## The rule will be given an arbitrary name
## Pass a list of rules. Each rule can be defined how you like
trading_rule1=(ewmac, 'rawdata.get_daily_prices', dict(Lfast=2, Lslow=8))
trading_rule2=dict(function=ewmac, other_args=dict(Lfast=4, Lslow=16))
rules=Rules([trading_rule1, tradingrule2])
## The rules will be given arbitrary names
## Pass a dict of rules. Each rule can be defined how you like
trading_rule1=(ewmac, 'rawdata.get_daily_prices', dict(Lfast=2, Lslow=8))
trading_rule2=dict(function=ewmac, other_args=dict(Lfast=4, Lslow=16))
rules=Rules(dict(ewmac2_8=trading_rule1, ewmac4_16=tradingrule2))
A very common development pattern is to create a trading rule with some parameters that can be changed, and then to produce a number of variations. Two functions are provided to make this easier.
from systems.trading_rules import TradingRule, create_variations_oneparameter, create_variations
## Let's create 3 variations of ewmac
## The default ewmac has Lslow=128
## Let's keep that fixed and vary Lfast
rule = TradingRule("systems.provided.rules.ewmac.ewmac_forecast_with_defaults")
variations = create_variations_oneparameter(rule, [4, 10, 100], "ewmac_Lfast")
variations.keys()dict_keys(['ewmac_Lfast_4', 'ewmac_Lfast_10', 'ewmac_Lfast_100'])
## Now let's vary both Lslow and Lfast
rule=TradingRule("systems.provided.rules.ewmac.ewmac_forecast_with_defaults")
## each separate rule is specified by a dict. We could use a lambda to produce these automatically
variations=create_variations(rule, [dict(Lfast=2, Lslow=8), dict(Lfast=4, Lslow=16)], key_argname="Lfast")
variations.keys()
dict_keys(['ewmac_Lfast_4', 'ewmac_Lfast_2'])
variations['Lfast_2'].other_args
{'Lfast': 4, 'Lslow': 16}We'd now create an instance of Rules(), passing variations in as an argument.
Once we have our new rules object we can create a new system with it:
## build the system
system=System([rules, RawData()], data, config)It's generally a good idea to put new fixed forecast scalars (see forecasting scaling and capping ) and forecast weights into the config (see the combining stage ); although if you're estimating these parameters automatically this won't be a problem. Or if you're just playing with ideas you can live with the default forecast scale of 1.0, and you can delete the forecast weights so that the system will default to using equal weights:
del(config.forecast_weights)If we've got a pre-baked system and a new set of trading rules we want to try that aren't in a config, we can pass them into the system when it's created:
from systems.provided.futures_chapter15.basesystem import futures_system
## we now create my_rules as we did above, for example
trading_rule1=(ewmac, 'rawdata.get_daily_prices', dict(Lfast=2, Lslow=8))
trading_rule2=dict(function=ewmac, other_args=dict(Lfast=4, Lslow=16))
system=futures_system(trading_rules=dict(ewmac2_8=trading_rule1, ewmac4_16=tradingrule2)) ## we may need to change the configurationThe workflow above has been to create a Rules instance (either empty, or
passing in a set of trading rules), then create a system that uses it. However
sometimes we might want to modify the list of trading rules in the system
object. For example you may have loaded a pre-baked system in (which will have
an empty Rules() instance and so be using the rules from the config). Rather
than replace that wholesale, you might want to drop one of the rules, add an
additional one, or change a rule that already exists.
To do this we need to directly access the private _trading_rules attribute
that stores processed trading rules in a dict. This means we can't pass in
any old rubbish that can be parsed into a trading rule as we did above; we need
to pass in actual TradingRule objects.
from systems.provided.futures_chapter15.basesystem import futures_system
from systems.trading_rules import TradingRule
system = futures_system()
## Parse the existing rules in the config (not required if you're going to backtest first as this will call this method doing its normal business)
system.rules.trading_rules()
#############
## add a rule by accessing private attribute
new_rule = TradingRule(
"systems.provided.futures_chapter15.rules.ewmac") ## any form of [TradingRule](#TradingRule) is fine here
system.rules._trading_rules['new_rule'] = new_rule
#############
#############
## modify a rule with existing key 'ewmac2_8'
modified_rule = system.rules._trading_rules['ewmac2_8']
modified_rule.other_args['Lfast'] = 10
## We can also do:
## modified_rule.function=new_function
## modified_rule.data='data.get_raw_price'
##
system.rules._trading_rules['ewmac2_8'] = modified_rule
#############
#############
## delete a rule (not recommended)
## Removing the rule from the set of fixed forecast_weights or rule_variations (used for estimating forecast_weights) would have the same effect - and you need to do this anyway
## Rules which aren't in the list of variations or weights are not calculated, so there is no benefit in deleting a rule in terms of speed / space
##
system.rules._trading_rules.pop("ewmac2_8")
#############Stage: Forecast scale and cap ForecastScaleCap class
This is a simple stage that performs two steps:
- Scale forecasts so they have the right average absolute value, by multiplying raw forecasts by a forecast scalar
- Cap forecasts at a maximum value
The standard configuration uses fixed scaling and caps. It is included in standard futures system.
Forecast scalars are specific to each rule. Scalars can either be included in
the trading_rules or forecast_scalars part of the config. The former takes
precedence if both are included:
YAML: (example)
trading_rules:
some_rule_name:
function: systems.futures.rules.arbitrary_function
forecast_scalar: 10.6
YAML: (example)
forecast_scalars:
some_rule_name: 10.6
The forecast cap is also configurable, but must be the same for all rules:
YAML:
forecast_cap: 20.0
If entirely missing default values of 1.0 and 20.0 are used for the scale and cap respectively.
See this blog post.
You may prefer to estimate your forecast scales from the available data. This
is often necessary if you have a new trading rule and have no idea at all what
the scaling should be. To do this you need to turn on estimation
config.use_forecast_scale_estimates=True. It is included in the pre-baked
estimated futures system.
All the config parameters needed are stored in
config.forecast_scalar_estimate.
You can either estimate scalars for individual instruments, or using data
pooled across instruments. The config parameter pool_instruments determines
which option is used.
We do this if pool_instruments=True. This defaults to using the function
"sysquant.estimators.forecast_scalar.forecast_scalar", but this is configurable using the parameter
func. If you're changing this please see configuring defaults for your own
functions.
I strongly recommend using pooling, since it's always good to get more data. The only reason not to use it is if you've been an idiot and designed a forecast for which the scale is naturally different across instruments (see chapter 7 of my book).
This function calculates a cross sectional median of absolute values, then works out the scalar to get it 10, using a rolling moving average (so always out of sample).
I also recommend using the defaults, a window size of 250000 (essentially
long enough so you're estimating with an expanding window) and min_periods of
500 (a couple of years of daily data; less than this and we'll get something
too unstable especially for a slower trading rule, more and we'll have to wait
too long to get a value). The other parameter of interest is backfill which
is boolean and defaults to True. This backfills the first scalar value found
back into the past so we don't lose any data; strictly speaking this is
cheating but we're not selecting the parameter for performance reasons so I for
one can sleep at night.
Note: The pooled estimate is cached as an 'across system', non instrument specific, item.
We do this if pool_instruments=False. Other parameters work in the same way.
Note: The estimate is cached separately for each instrument.
Stage: Forecast combine ForecastCombine class
We now take a weighted average of forecasts using instrument weights, and multiply by the forecast diversification multiplier.
The default fixed weights and a fixed multiplier. It is included in the pre-baked standard futures system.
Both weights and multiplier are configurable.
Forecast weights can be (a) common across instruments, or (b) specified differently for each instrument. If not included equal weights will be used.
YAML: (a)
forecast_weights:
ewmac: 0.50
carry: 0.50
YAML: (b)
forecast_weights:
SP500:
ewmac: 0.50
carry: 0.50
US10:
ewmac: 0.10
carry: 0.90
The diversification multiplier can also be (a) common across instruments, or (b) we use a different one for each instrument (would be normal if instrument weights were also different).
YAML: (a)
forecast_div_multiplier: 1.0
YAML: (b)
forecast_div_multiplier:
SP500: 1.4
US10: 1.1
Note that the get_combined_forecast method in the standard fixed base class
automatically adjusts forecast weights if different trading rules have
different start dates for their forecasts. It does not adjust the multiplier.
This means that in the past the multiplier will probably be too high.
This behaviour is included in the pre-baked estimated futures
system. We switch to it by setting
config.use_forecast_weight_estimates=True and/or
config.use_forecast_div_mult_estimates=True.
See optimisation for more information.
See optimisation for more information.
See estimating diversification multipliers.
A new optional feature introduced in version 0.18.2 is forecast mapping. This is the non linear mapping discussed in this blog post whereby we do not take a forecast until it has reached some threshold. Because this will reduce the standard deviation of our forecasts we compensate by ramping up the forecast more quickly until the raw forecast reaches the existing cap (which defaults to 20). This is probably illustrated better if we look at the non-linear mapping function:
#This is syscore.algos.map_forecast_value
def map_forecast_value_scalar(x, threshold, capped_value, a_param, b_param):
"""
Non linear mapping of x value; replaces forecast capping; with defaults will map 1 for 1
We want to end up with a function like this, for raw forecast x and mapped forecast m,
capped_value c and threshold_value t:
if -t < x < +t: m=0
if abs(x)>c: m=sign(x)*c*a
if c < x < -t: (x+t)*b
if t < x < +c: (x-t)*b
:param x: value to map
:param threshold: value below which map to zero
:param capped_value: maximum value we want x to take (without non linear mapping)
:param a_param: multiple at capped value
:param b_param: slope
:return: mapped x
"""
x = float(x)
if np.isnan(x):
return x
if abs(x)<threshold:
return 0.0
if x >= -capped_value and x <= -threshold:
return b_param*(x+threshold)
if x >= threshold and x <= capped_value:
return b_param*(x-threshold)
if abs(x)>capped_value:
return sign(x)*capped_value*a_param
raise Exception("This should cover all conditions!")What values should we use for a,b and threshold (t)? We want to satisfy the following rules:
- a_param should be set so that we typically hold four contracts when the raw_forecast is at capped_value (see chapter 12 of my book, "Systematic Trading")
- We require b = (c*a)/(c-t)
- Given our parameters, and the distribution of the raw forecast (assumed to be Gaussian), the average absolute value of the final distribution should be unchanged.
These values aren't estimated by default, so you can use this external function:
# Assuming futures_system already contains a system which has positions
from systems.diagoutput import systemDiag
sysdiag = systemDiag(futures_system)
sysdiag.forecast_mapping()Parameters are specified by market as follows:
YAML:
forecast_mapping:
AEX:
a_param: 2.0
b_param: 8.0
threshold: 15.0
If the forecast_mapping key is missing from the configuration object, or the instrument is missing from the dict, then no mapping will be done (the raw forecast will remain unchanged). Also note that if a_param = b_param = 1, and threshold=0, then this is equivalent to no mapping.
Using the standard PositionSizing class
The annualised percentage volatility target, notional trading capital and currency of trading capital are all configurable.
YAML:
percentage_vol_target: 16.0
notional_trading_capital: 1000000
base_currency: "USD"
Note that the stage code tries to get the percentage volatility of an instrument from the rawdata stage. Since a rawdata stage might be omitted, it can also fall back to calculating this from scratch using the data object and the default volatility calculation method.
Stage: Creating portfolios Portfolios class
The instrument weights and instrument diversification multiplier are used to combine different instruments together into the final portfolio (chapter eleven of my book).
The default uses fixed weights and multiplier.
Both are configurable. If omitted equal weights will be used, and a multiplier of 1.0
YAML:
instrument_weights:
EDOLLAR: 0.5
US10: 0.5
instrument_div_multiplier: 1.2
Note that the get_instrument_weights method in the standard fixed base class
automatically adjusts raw forecast weights if different instruments have
different start dates for their price history and forecasts. It does not adjust
the multiplier. This means that in the past the multiplier will probably be too
high.
You can estimate the correct instrument diversification multiplier 'on the
fly', and also estimate instrument weights. This functionality is included in
the pre-baked estimated futures system. It is accessed by
setting config.use_instrument_weight_estimates=True and/or
config.use_instrument_div_mult_estimates=True.
See optimisation for more information.
See estimating diversification multipliers.
Position inertia, or buffering, is a way of reducing trading costs. The idea is that we avoid trading if our optimal position changes only slightly by applying a 'no trade' buffer around the current position. There is more on this subject in chapter 11 of my book.
There are two methods that I use. Position buffering is the same as the position inertia method used in my book. We compare the current position to the optimal position. If it's not within 10% (the 'buffer') then we trade to the optimal position, otherwise we don't bother.
This configuration will implement position inertia as in my book.
YAML:
buffer_trade_to_edge: False
buffer_method: position
buffer_size: 0.10
The second method is forecast buffering. Here we take a proportion of the average absolute position (what we get with a forecast of 10), and use that to size the buffer width. This is more theoretically correct; since the buffer doesn't shrink as we get to zero. Secondly if outside the buffer we trade to the nearest edge of the buffer, rather than going to the optimal position. This further reduces transaction costs. Here are my recommended settings for forecast buffering:
YAML:
buffer_trade_to_edge: True
buffer_method: forecast
buffer_size: 0.10
Note that buffering can work on both rounded and unrounded positions. In the case of rounded positions we round the lower limit of the buffer, and the upper limit.
These python methods allow you to see buffering in action.
system.portfolio.get_notional_position("US10") ## get the position before buffering
system.portfolio.get_buffers_for_position("US10") ## get the upper and lower edges of the buffer
system.accounts.get_buffered_position("US10", roundpositions=True) ## get the buffered position.
Note that in a live trading system buffering is done downstream of the system module, in a process which can also see the actual current positions we hold the strategy order generation).
Finally, if you set buffer_method to none there will be no buffering.
If you want to see positions that reflect varying capital, then read the section on capital correction.
The final stage is the all important accounting stage, which calculates p&l.
Using the standard Account class
The standard accounting class includes several useful methods:
portfolio: works out the p&l for the whole system (returns accountCurveGroup)pandl_for_instrument: the contribution of a particular instrument to the p&l (returns accountCurve)pandl_for_subsystem: work out how an instrument has done in isolation (returns accountCurve)pandl_across_subsystems: group together all subsystem p&l (not the same as portfolio! Instrument weights aren't used) (returns accountCurveGroup)pandl_for_trading_rule: how a trading rule has done aggregated over all instruments (returns accountCurveGroup)pandl_for_trading_rule_weighted: how a trading rule has done over all instruments as a proportion of total capital (returns accountCurveGroup)pandl_for_trading_rule_unweighted: how a trading rule has done over all instruments, unweighted (returns accountCurveGroup)pandl_for_all_trading_rules: how all trading rules have done over all instruments (returns nested accountCurveGroup)pandl_for_all_trading_rules_unweighted: how all trading rules have done over all instruments, unweighted (returns nested accountCurveGroup)pandl_for_instrument_rules: how all trading rules have done for a particular instrument (returns accountCurveGroup)pandl_for_instrument_rules_unweighted: how all trading rules have done for one instrument, unweighted (returns accountCurveGroup)pandl_for_instrument_forecast: work out how well a particular trading rule variation has done with a particular instrument (returns accountCurve)pandl_for_instrument_forecast_weighted: work out how well a particular trading rule variation has done with a particular instrument as a proportion of total capital (returns accountCurve)
(Note that buffered positions are only used at the final portfolio stage; the positions for forecasts and subsystems are not buffered. So their trading costs may be a little overstated).
(Warning: see weighted and unweighted account curve groups )
Most of these classes share some useful arguments (all boolean):
delayfill: Assume we trade at the next days closing price. Always defaults to True (more conservative)roundpositions: Round positions to nearest instrument block. Defaults to True for portfolios and instruments, defaults to False for subsystems. Not used inpandl_for_instrument_forecastorpandl_for_trading_rule(always False)
All p&l methods return an object of type accountCurve (for instruments,
subsystems and instrument forecasts) or accountCurveGroup (for portfolio and
trading rule), or even nested accountCurveGroup
(pandl_for_all_trading_rules, pandl_for_all_trading_rules_unweighted). This
inherits from a pandas data frame, so it can be plotted, averaged and so on. It
also has some special methods. To see what they are use the stats method:
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
system.accounts.portfolio().stats()[[('min', '-1.997e+05'),
('max', '4.083e+04'),
('median', '-1.631'),
('mean', '156.9'),
('std', '5226'),
('skew', '-7.054'),
('ann_mean', '4.016e+04'),
('ann_std', '8.361e+04'),
('sharpe', '0.4803'),
('sortino', '0.5193'),
('avg_drawdown', '-1.017e+05'),
('time_in_drawdown', '0.9621'),
('calmar', '0.1199'),
('avg_return_to_drawdown', '0.395'),
('avg_loss', '-3016'),
('avg_gain', '3371'),
('gaintolossratio', '1.118'),
('profitfactor', '1.103'),
('hitrate', '0.4968'),
('t_stat', '2.852'),
('p_value', '0.004349')],
('You can also plot / print:',
['rolling_ann_std', 'drawdown', 'curve', 'percent'])]
The stats method lists three kinds of output:
- Statistics which can also be extracted with their own methods eg to extract
sortino use
system.accounts.portfolio().sortino() - Methods which can be used to do interesting plots eg
system.accounts.portfolio().drawdown() - Attributes which can be used to get returns over different periods, eg
systems.accounts.portfolio().annual
There is a lot more to accountCurve and group objects than meets the eye.
Let's start with accountCurve, which is the output you get from
systems.account.pandl_for_subsystem amongst other things
acc_curve=system.accounts.pandl_for_subsystem("EDOLLAR")This looks like a pandas data frame, where each day is a different return. However it's actually a bit more interesting than that. There's actually three different account curves buried inside this; gross p&l without costs, costs, and net including costs. We can access any of them like so:
acc_curve.gross
acc_curve.net
acc_curve.costs
acc_curve.to_ncg_frame() ## this method returns a data frame with all 3 elements as columnsThe net version is identical to acc_curve; this is deliberate to encourage you to look at net returns. Each curve defaults to displaying daily returns, however we can also access different frequencies (daily, weekly, monthly, annual):
acc_curve.gross.daily ## equivalent to acc_curve.gross
acc_curve.net.daily ## equivalent to acc_curve and acc_curve.net
acc_curve.net.weekly ## or also acc_curve.weekly
acc_curve.costs.monthlyOnce you have the frequency you require you can then use any of the statistical methods:
acc_curve.gross.daily.stats() ## Get a list of methods. equivalent to acc_curve.gross.stats()
acc_curve.annual.sharpe() ## Sharpe ratio based on annual
acc_curve.gross.weekly.std() ## standard deviation of weekly returns
acc_curve.daily.ann_std() ## annualised std. deviation of daily (net) returns
acc_curve.costs.annual.median() ## median of annual costs... or other interesting methods:
import syscore.pandas.strategy_functions
acc_curve.rolling_ann_std() ## rolling annual standard deviation of daily (net) returns
acc_curve.gross.curve() ## cumulated returns = account curve of gross daily returns
syscore.pandas.strategy_functions.drawdown() ## drawdown of monthly net returns
acc_curve.costs.weekly.curve() ## cumulated weekly costsPersonally I prefer looking at statistics in percentage terms. This is easy. Just use the .percent property before you use any statistical method:
import syscore.pandas.strategy_functions
acc_curve.capital ## tells me the capital I will use to calculate %
acc_curve.percent
acc_curve.gross.daily.percent
acc_curve.net.daily.percent
acc_curve.costs.monthly.percent
acc_curve.gross.daily.percent.stats()
acc_curve.monthly.percent.sharpe()
acc_curve.gross.weekly.percent.std()
acc_curve.daily.percent.ann_std()
acc_curve.costs.annual.percent.median()
acc_curve.percent.rolling_ann_std()
acc_curve.gross.percent.curve()
syscore.pandas.strategy_functions.drawdown()
acc_curve.costs.weekly.percent.curve()Incidentally you can 'daisy-chain' the percentage, frequency, and gross/net/costs operators in any order; the underlying object isn't actually changed, it's just the representation of it that is modified. If you want to reverse a percentage operator you can use .value_terms().
accountCurveGroup, is the output you get from systems.account.portfolio,
systems.account.pandl_across_subsystems,
pandl_for_instrument_rules_unweighted, pandl_for_trading_rule and
pandl_for_trading_rule_unweighted. For example:
acc_curve_group=system.accounts.portfolio()Again this looks like a pandas data frame, or indeed like an ordinary account curve object. So for example these all work:
acc_curve_group.gross.daily.stats() ## Get a list of methods. equivalent to acc_curve.gross.stats()
acc_curve_group.annual.sharpe() ## Sharpe ratio based on annual
acc_curve_group.gross.weekly.std() ## standard deviation of weekly returns
acc_curve_group.daily.ann_std() ## annualised std. deviation of daily (net) returns
acc_curve_group.costs.annual.median() ## median of annual costsThese are in fact all giving the p&l for the entire portfolio (the sum of
individual account curves across all assets); defaulting to giving the net,
daily curve. To find out which assets we use acc_curve_group.asset_columns; to
access a particular asset we use acc_curve_group['assetName'].
acc_curve_group.asset_columns
acc_curve_group['US10']Warning see weighted and unweighted account curve groups
The second command returns the account curves just for US 10 year bonds. So we can do things like:
acc_curve_group['US10'].gross.daily.stats() ## Get a list of methods. equivalent to acc_curve.gross.stats()
acc_curve_group['US10'].annual.sharpe() ## Sharpe ratio based on annual
acc_curve_group['US10'].gross.weekly.std() ## standard deviation of weekly returns
acc_curve_group['US10'].daily.ann_std() ## annualised std. deviation of daily (net) returns
acc_curve_group['US10'].costs.annual.median() ## median of annual costs
acc_curve_group.gross['US10'].weekly.std() ## notice equivalent way of getting account curvesSometimes it's nicer to plot all the individual account curves, so we can get a data frame.
acc_curve_group.to_frame() ## returns net account curves all assets in a frame
acc_curve_group.net.to_frame() ## returns net account curves all assets in a frame
acc_curve_group.gross.to_frame() ## returns net account curves all assets in a frame
acc_curve_group.costs.to_frame() ## returns net account curves all assets in a frameWarning see weighted and unweighted account curve groups
The other thing you can do is get a dictionary of any statistical method, measured across all assets:
acc_curve_group.get_stats("sharpe", "net", "daily") ## get all annualised sharpe ratios using daily data
acc_curve_group.get_stats("sharpe", freq="daily") ## equivalent
acc_curve_group.get_stats("sharpe", curve_type="net") ## equivalent
acc_curve_group.net.get_stats("sharpe", freq="daily") ## equivalent
acc_curve_group.net.get_stats("sharpe", percent=False) ## defaults to giving stats in % terms, this turns it offWarning see weighted and unweighted account curve groups
You can get summary statistics for these. These can either be simple averages across all assets, or time weighted by the amount of data each asset has.
acc_curve_group.get_stats("sharpe").mean() ## get simple average of annualised sharpe ratios for net returns using daily data
acc_curve_group.get_stats("sharpe").std(timeweighted=True) ## get time weighted standard deviation of sharpes across assets,
acc_curve_group.get_stats("sharpe").tstat(timeweighted=False) ## t tstatistic for average sharpe ratio
acc_curve_group.get_stats("sharpe").pvalue(timeweighted=True) ## p value of t statistic of time weighted average sharpe ratio.A nested accountCurveGroup, is the output you get from
pandl_for_all_trading_rules and pandl_for_all_trading_rules_unweighted. For
example:
nested_acc_curve_group=system.accounts.pandl_for_all_trading_rules()This is an account curve group, whose elements are the performance of each trading rule eg this kind of thing works:
ewmac64_acc=system.accounts.pandl_for_all_trading_rules()['ewmac64_256']However this is also an accountCurveGroup! So you can, for example display how each instrument within this trading rule contributed to performance as a data frame:
ewmac64_acc.to_frame()There are two types of account curve; weighted and unweighted. Weighted curves include returns for each instrument (or trading rule) as a proportion of the total capital at risk. Unweighted curves show each instrument or trading rule in isolation.
Weighted:
portfolio: works out the p&l for the whole system (weighted group - elements arepandl_for_instrument- effective weights are instrument weights * IDM)pandl_for_instrument: the contribution of a particular instrument to the p&l (weighted individual curve for one instrument - effective weight is instrument weight * IDM) -pandl_for_instrument_rules: how all trading rules have done for a particular instrument (weighted group - elements arepandl_for_instrument_forecastacross trading rules; effective weights are forecast weights * FDM)pandl_for_instrument_forecast_weighted: work out how well a particular trading rule variation has done with a particular instrument as a proportion of total capital (weighted individual curve - weights are forecast weight * FDM * instrument weight * IDM)pandl_for_trading_rule_weighted: how a trading rule has done over all instruments as a proportion of total capital (weighted group -elements arepandl_for_instrument_forecast_weightedacross instruments - effective weights are risk contribution of instrument to trading rule)pandl_for_all_trading_rules: how all trading rules have done over all instruments (weighted group -elements arepandl_for_trading_rule_weightedacross variations - effective weight is risk contribution of each trading rule)
Partially weighted (see below):
pandl_for_trading_rule: how a trading rule has done over all instruments (weighted group -elements arepandl_for_instrument_forecast_weightedacross instruments, weights are risk contribution of each instrument to trading rule)
Unweighted:
pandl_across_subsystems: works out the p&l for all subsystems (unweighted group - elements arepandl_for_subsystem)pandl_for_subsystem: work out how an instrument has done in isolation (unweighted individual curve for one instrument)pandl_for_instrument_forecast: work out how well a particular trading rule variation has done with a particular instrument (unweighted individual curve)pandl_for_instrument_rules_unweighted: how all trading rules have done for a particular instrument (unweighted group - elements arepandl_for_instrument_forecastacross trading rules)pandl_for_trading_rule_unweighted: how a trading rule has done over all instruments (unweighted group -elements arepandl_for_instrument_forecastacross instruments)pandl_for_all_trading_rules_unweighted: how all trading rules have done over all instruments (unweighted group -elements arepandl_for_trading_ruleacross instruments - effective weight is risk contribution of each trading rule)
Note that pandl_across_subsystems / pandl_for_subsystem are effectively the
unweighted versions of portfolio / pandl_for_instrument.
The difference is important for a few reasons.
- Firstly the return and risk of individual weighted curves will be lower than the target
- The returns of individual weighted curves will also be highly non stationary, at least for instruments. This is because the weightings of instruments within a portfolio, or a trading rule, will change over time. Usually there are fewer instruments. This means that the risk profile will show much higher returns earlier in the series. Statistics such as sharpe ratio may be highly misleading.
- The portfolio level aggregate returns of unweighted group curves will make no sense. They will be equally weighted, whereas we'd normally have different weights.
- Also for portfolios of unweighted groups risk will usually fall over time as markets are added and diversification effects appear. Again this is more problematic for groups of instruments (within a portfolio, or within a trading rule)
Weighting for trading rules p&l is a little complicated.
pandl_for_instrument_forecast: If I want the p&l of a single trading rule
for one instrument in isolation, then I use pandl_for_instrument_forecast.
pandl_for_trading_rule_unweighted: If I aggregate these across instruments
then I get pandl_for_trading_rule_unweighted. The individual unweighted
curves are instrument p&l for each instrument and forecast.
pandl_for_instrument_forecast_weighted: The weighted p&l of a single
trading rule for one instrument, as a proportion of the entire system's
capital, will be it's individual p&l in isolation
(pandl_for_instrument_forecast) multiplied by the product of the instrument
and forecast weights, and the IDM and FDM (this ignores the effect of total
forecast capping and position buffering or inertia).
pandl_for_trading_rule_weighted: The weighted p&l of a single trading rule
across individual instruments, as a proportion of the entire system's
capital, will be the group of pandl_for_instrument_forecast_weighted of
these for a given rule. You can get this with
pandl_for_trading_rule_weighted. The individual curves within this will be
instrument p&l for the relevant trading rule, effectively weighted by the
product of instrument, forecast weights, FDM and IDM. The risk of the total
curve will be equal to the risk of the rule as part of the total capital, so
will be lower than you'd expect.
pandl_for_all_trading_rules: If I group the resulting curves across trading
rules, then I get pandl_for_all_trading_rules. The individual curves will be
individual trading rules, weighted by their contribution to total risk. The
total curve is the entire system; it will look close to but not exactly like a
portfolio account curve because of the non linear effects of combined
forecast capping, and position buffering or inertia, and rounding if that's
used for the portfolio curve.
pandl_for_trading_rule: If I want the performance of a given trading rule
across individual instruments in isolation, then I need to take
pandl_for_trading_rule_weighted and normalise it so that the returns are as a
proportion of the sum of all the relevant forecast weight * FDM * instrument
weight * IDM; this is equivalent to the rules risk contribution within the
system. . This is an unweighted curve in one sense (it's not a proportion of
total capital), but it's weighted in another (the individual curves when added
up give the group curve). The total account curve will have the same target
risk as the entire system. The individual curves within it are for each
instrument, weighted by their contribution to risk.
pandl_for_all_trading_rules_unweighted: If I group these curves together,
then I get pandl_for_all_trading_rules_unweighted. The individual curves will
be individual trading rules but not weighted; so each will have its own risk
target. This is an unweighted group in the truest sense; the total curve won't
make sense.
To summarise:
- Individual account curves either in, or outside, a weighted group should be treated with caution. But the entire portfolio curve is fine.
- The portfolio level account curve for an unweighted group should be treated with caution. But the individual curves are fine.
- With the exception of
pandl_for_trading_rulethe portfolio level curve for a weighted group is a proportion of the entire system capital.
The attribute weighted is set to either True (for weighted curves
including pandl_for_trading_rule) or False (otherwise). All curve repr
methods also show either weighted or unweighted status.
If you want to know how significant the returns for an account curve are (no
matter where you got it from), then use the method accurve.t_test(). This
returns the two sided t-test statistic and p-value for a null hypothesis of a
zero mean.
Sometimes you might want to compare the performance of two systems, instruments
or trading rules. The function from syscore.accounting import account_t_test
can be used for this purpose. The two parameters can be anything that looks
like an account curve, no matter where you got it from.
When run it returns a two sided t-test statistic and p-value for the null hypothesis of identical means. This is done on the period of time that both objects are trading.
Warning: The assumptions underlying a t-test may be violated for financial data. Use with care.
I work out costs in two different ways:
- by applying a constant drag calculated according to the standardised cost in Sharpe ratio terms and the estimated turnover (see chapter 12 of my book)
- using the actual costs for each trade.
The former method is always used for costs derived from forecasts
(pandl_for_instrument_forecast, pandl_for_instrument_forecast_weighted,
pandl_for_trading_rule, pandl_for_all_trading_rules,
pandl_for_all_trading_rules_unweighted, pandl_for_trading_rule_unweighted,
pandl_for_trading_rule_weighted, pandl_for_instrument_rules_unweighted, and
pandl_for_instrument_rules).
For costs derived from actual positions (everything else) we can use either method. Actual cash costs are more accurate especially if your system has sparse positions (eg the dynamic optimised system I describe elsewhere). However it's quicker to use SR costs, so if you set use_SR_costs=True you will speed things up with some loss of accuracy.
Both cost methods now account for holding - rollover costs.
Note that 'actual costs' are normally standardised for historic volatility (although you can optionally turn this off in config vol_normalise_currency_costs=False which is useful for comparing with live trading purposes, but I do not recommend it for historical purposes as I don't think it is accurate in the past)
Costs that can be included are:
- Slippage, in price points. Half the bid-ask spread, unless trading in large size or with a long history of trading at a better cost.
- Cost per instrument block, in local currency. This is used for most futures.
- Percentage of value costs (0.01 is 1%). Used for US equities.
- Per trade costs, in local currency. Common for UK brokers. This won't be
applied correctly unless
roundpositions=Truein the accounts call.
To see the turnover that has been estimated use:
system.accounts.turnover_at_portfolio_level() ## Total portfolio turnover
system.accounts.subsystem_turnover(instrument_code) ### Annualised turnover of subsystem
system.accounts.instrument_turnover(instrument_code) ### Annualised turnover of portfolio level position
system.accounts.forecast_turnover(instrument_code, rule_variation_name) ## Annualised turnover of forecast
Instrument level turnovers are accurate for the vanilla system but may be misleading for systems with sparse positions (eg the dynamic optimised system I describe elsewhere) because the notion of 'average position' is difficult to quantify.
To see holding costs in SR units:
system.accounts.get_rolls_per_year("EDOLLAR") ## four
system.accounts.get_SR_cost_per_trade_for_instrument("EDOLLAR") ## about 1 SR unit
system.accounts.get_SR_holding_cost_only("EDOLLAR") ## cost of 4 rolls per year: which is two 'turnovers'
system.accounts.get_SR_trading_cost_only_given_turnover("EDOLLAR", 5.0) ## trading five times a year, no holding cost
system.accounts.get_SR_cost_given_turnover("EDOLLAR", 5) ## includes both holding and trading costs for a turnover of 5
system.accounts.get_SR_cost_for_instrument_forecast("EDOLLAR", "carry") ## includes both
system.accounts.pandl_for_subsystem("EDOLLAR") ## includes both, assuming you're using SR costs
For calculating forecast costs (pandl_for_instrument_forecast... and so on.
Note these are used for estimating forecast weights) I offer the option to pool
costs across instruments. You can either pool the estimate of turnovers (which
I recommend), or pool the average of cost * turnover (which I don't recommend).
Averaging in the pooling process is always done with more weight given to
instruments that have more history.
forecast_cost_estimate:
use_pooled_costs: False
use_pooled_turnover: True
This section gives much more detail on certain important processes that span multiple stages: logging, estimating correlations and diversification multipliers, optimisation, and capital correction.
There are a number of different ways one might want to specify path and file names. Firstly, we could use a relative pathname. Secondly, we might want to use an absolute path, which is the actual full pathname. This is useful if we want to access something outside the pysystemtrade directory structure. Finally we have the issue of OS differences; are you a '\' or a '/' person?
For convenience I have written some functions that translate between these different formats, and the underlying OS representation.
from syscore.fileutils import get_resolved_pathname, resolve_path_and_filename_for_package
# Resolve both filename and pathname jointly. Useful when writing the name of eg a configuration file
## Absolute format
### Windows (note use of double backslash in str) Make sure you include the initial backslash, or will be treated as relative format
resolve_path_and_filename_for_package("\\home\\rob\\file.csv")
### Unix. Make sure you include the initial forward slash,
resolve_path_and_filename_for_package("/home/rob/file.csv")
## Relative format to find a file in the installed pysystemtrade
### Dot format. Notice there is no initial 'dot' and we don't need to include 'pysystemtrade'
resolve_path_and_filename_for_package("syscore.tests.pricedata.csv")
# Specify the path and filename separately
resolve_path_and_filename_for_package("\\home\\rob", "file.csv")
resolve_path_and_filename_for_package("/home/rob", "file.csv")
resolve_path_and_filename_for_package("syscore.tests", "pricedata.csv")
# Resolve just the pathname
get_resolved_pathname("/home/rob")
get_resolved_pathname("\\home\\rob")
get_resolved_pathname("syscore.tests")
## DON'T USE THESE:-
### It's possible to use Unix or Windows for relative filenames, but I prefer not to, so there is a clearer disctinction between absolute and relative.
### However this works:
resolve_path_and_filename_for_package("syscore/tests/pricedata.csv")
### Similarly, I prefer not to use dot format for absolute filenames but it will work
resolve_path_and_filename_for_package(".home.rob.file.csv")
### Finally, You can mix and match the above formats in a single string, but it won't make the code very readable!
resolve_path_and_filename_for_package("\\home/rob.file.csv")These functions are used internally whenever a file name is passed in, so feel free to use any of these file formats when specifying eg a configuration filename.
### Absolute: Windows (note use of double backslash in str)
"\\home\\rob\\file.csv"
### Absolute: Unix.
"/home/rob/file.csv"
## Relative: Dot format to find a file in the installed pysystemtrade
"syscore.tests.pricedata.csv"
pysystemtrade uses the Python logging module. The system, data, config and each stage object all have a .log attribute, to allow the system to report to the user; as do the functions provided to estimate correlations and do optimisations.
By default, log messages will print out to the console (std.out) at level DEBUG. This what you get in sim. This is configured by function _configure_sim() in syslogging.logger.py.
If you want to change the level, or the format of the messages, then create an environment variable that points to an alternative YAML logging configuration. Something like this for Bash
PYSYS_LOGGING_CONFIG=/home/path/to/your/logging_config.yaml
It could be a file within the project, so will accept the relative dotted path format. There's an example YAML file that replicates the default sim configuration
PYSYS_LOGGING_CONFIG=syslogging.logging_sim.yaml
If you're writing your own code, and want to inform the user that something is happening you should do one of the following:
## self could be a system, stage, config or data object
#
self.log.debug("this is a message at level logging.DEBUG")
self.log.info("this is a message at level logging.INFO")
self.log.warning("level logging.WARNING")
self.log.error("level logging.ERROR")
self.log.critical("level logging.CRITICAL")
# parameterise the message
log.info("Hello %s", "world")
log.info("Goodbye %s %s", "cruel", "world")I strongly encourage the use of logging, rather than printing, since printing on a 'headless' automated trading server will not be visible
In my experience wading through long log files is a rather time-consuming experience. On the other hand it's often more useful to use a logging approach to monitor system behaviour than to try and create quantitative diagnostics. For this reason I'm a big fan of logging with attributes. This project uses a custom version of logging.LoggerAdapter for that purpose:
from syslogging.logger import *
# setting attributes on logger initialisation
log = get_logger("logger name", {"stage": "first"})
# setting attributes on message creation
log.info("logger name", instrument_code="GOLD")A logger is initialised with a name; should be the name of the top level calling function. Production types include price collection, execution and so on. Every time a log method is called, it will typically know one or more of the following:
- stage: Used by stages in System objects, such as 'rawdata'
- component: other parts of the top level function that have their own loggers
- currency_code: Currency code (used for fx), format 'GBPUSD'
- instrument_code: Self explanatory
- contract_date: Self explanatory, format 'yyyymm'
- broker: broker name
- clientid: IB unique identification
- strategy_name: self explanatory
- order_id: Self explanatory, used for live trading
- instrument_order_id: Self explanatory, used for live trading
- contract_order_id: Self explanatory, used for live trading
- broker_order_id: Self explanatory, used for live trading
You do need to keep track of what attributes your logger has. Generally speaking you should use this kind of pattern to write a log item
# this is from the ForecastScaleCap code
#
# This log will already have type=base_system, and stage=forecastScaleCap
#
self.log.debug("Calculating scaled forecast for %s %s" % (instrument_code, rule_variation_name),
instrument_code=instrument_code, rule_variation_name=rule_variation_name
)This has the advantage of keeping the original log attributes intact. If you want to do something more complex it's worth looking at the docstring for syslogging.get_logger() which shows usage patterns, including how to merge attributes.
See my blog posts on optimisation: without and with costs.
I use an optimiser to calculate both forecast and instrument weights. The process is almost identical for both.
From the config
forecast_weight_estimate: ## can also be applied to instrument weights
func: sysquant.optimisation.generic_optimiser.genericOptimiser ## this is the only function provided
pool_instruments: True ## not used for instrument weights
frequency: "W" ## other options: D, M, Y
I recommend using weekly data, since it speeds things up and doesn't affect out of sample performance.
Again I recommend you check out this blog post.
forecast_weight_estimate:
ceiling_cost_SR: 0.13 ## Max cost to allow for assets, annual SR units.
See 'costs' to see how to configure pooling when estimating the costs of forecasts.
By default this is set to 9999 which effectively means that all trading rules are included at the optimisation stage. However the use of post_ceiling_cost_SR can be used to remove rules that are too expensive. This is recommended if you are pooling gross returns.
Pooling across instruments is only available when calculating forecast weights.
Again I recommend you check out this blog
post.
Only instruments whose rules have survived the application of a ceiling cost (ceiling_cost_SR)
will be included in the pooling process. If you want to pool all instruments, regardless of costs, then you should set ceiling_cost_SR to be some high number, and use post_ceiling_cost_SR instead to eliminate expensive rules after the optimisation is complete (this is the default).
forecast_weight_estimate:
pool_gross_returns: True ## pool gross returns for estimation
forecast_cost_estimate:
use_pooled_costs: False ### use weighted average of [SR cost * turnover] across instruments with the same set of trading rules
use_pooled_turnover: True ### Use weighted average of turnover across instruments with the same set of trading rules
See 'costs' to see how to configure pooling when estimating the costs of forecasts.
Again I recommend you check out this blog post.
forecast_weight_estimate: ## can also be applied to instrument weights
equalise_gross: False ## equalise gross returns so that only costs are used for optimisation
cost_multiplier: 0.0 ## multiply costs by this number. Zero means grosss returns used. Higher than 1 means costs will be inflated. Use zero if apply_cost_weight=True (see later)
There are three options available for the fitting period - expanding
(recommended), in sample (never!) and rolling. See Chapter 3 of my book.
From the config
date_method: expanding ## other options: in_sample, rolling
rollyears: 20 ## only used when rolling
To do an optimisation we need estimates of correlations, means, and standard deviations.
From the config
forecast_weight_estimate: ## can also be applied to instrument weights
correlation_estimate:
func: sysquant.estimators.correlation_estimator.correlationEstimator
using_exponent: False
ew_lookback: 500
min_periods: 20
floor_at_zero: True
mean_estimate:
func: sysquant.estimators.mean_estimator.meanEstimator
using_exponent: False
ew_lookback: 500
min_periods: 20
vol_estimate:
func: sysquant.estimators.stdev_estimator.stdevEstimator
using_exponent: False
ew_lookback: 500
min_periods: 20
If you're using shrinkage or single period optimisation I'd suggest using an exponential weight for correlations, means, and volatility.
There are five methods provided to optimise with in the function I've included. Personally I'd use handcrafting, which is the default.
This will give everything in the optimisation equal weights.
method: equal_weights
Tip: Set date_method: in_sample to speed things up.
This is the classic Markowitz optimisation with the option to equalise Sharpe Ratios (makes things more stable) and volatilities. Since we're dealing with things that should have the same volatility anyway the latter is something I recommend doing.
method: one_period
equalise_SR: True
ann_target_SR: 0.5 ## Sharpe we head to if we're equalising
equalise_vols: True
Notice that if you equalise Sharpe then this will override the effect of any pooling or changes to cost calculation.
Bootstrapping is no longer implemented; after a code refactoring I couldn't think of an elegant way of doing it.
This is a basic shrinkage towards a prior of equal sharpe ratios, and equal correlations; with priors equal to the average of estimates from the data. Shrinkage of 1.0 means we use the priors, 0.0 means we use the empirical estimates.
method: shrinkage
shrinkage_SR: 0.90
ann_target_SR: 0.5 ## Sharpe we head to if we're shrinking
shrinkage_corr: 0.50
equalise_vols: True
Notice that if you equalise Sharpe by shrinking with a factor of 1.0, then this will override the effect of any pooling or changes to cost calculation.
method: handcraft
equalise_SR: False # optional
equalise_vols: True ## This *must* be true for the code to work
If we haven't accounted for costs earlier (eg by setting cost_multiplier=0)
then we can adjust our portfolio weights according to costs after they've been
calculated. See this blog post blog
post.
If weights are cleaned, then in a fitting period when we need a weight, but none has been calculated (due to insufficient data for example), an instrument is given a share of the weight.
apply_cost_weight: False
cleaning: True
At this stage the other cost ceiling will be applied (config.post_ceiling_cost_SR).
See my blog post
You can estimate diversification multipliers for both instruments (IDM - see chapter 11) and forecasts (FDM - see chapter 8).
The first step is to estimate correlations. The process is the same, except that for forecasts you have the option to pool instruments together. As the following YAML extract shows I recommend estimating these with an exponential moving average on weekly data:
forecast_correlation_estimate:
pool_instruments: True ## not available for IDM estimation
func:sysquant.estimators.pooled_correlation.pooled_correlation_estimator ## function to use for estimation. This handles both pooled and non pooled data
frequency: "W" # frequency to downsample to before estimating correlations
date_method: "expanding" # what kind of window to use in backtest
using_exponent: True # use an exponentially weighted correlation, or all the values equally
ew_lookback: 250 ## lookback when using exponential weighting
min_periods: 20 # min_periods, used for both exponential, and non exponential weighting
cleaning: True # Replace missing values with an average so we don't lose data early on
floor_at_zero: True
forward_fill_data: True
instrument_correlation_estimate:
func: sysquant.estimators.correlation_over_time.correlation_over_time_for_returns # these aren't pooled'
frequency: "W"
date_method: "expanding"
using_exponent: True
ew_lookback: 250
min_periods: 20
cleaning: True
rollyears: 20
floor_at_zero: True
forward_fill_price_index: True # we ffill prices not returns or goes wrong
Once we have correlations, and the forecast or instrument weights, it's a trivial calculation.
instrument_div_mult_estimate:
func: sysquant.estimators.diversification_multipliers.diversification_multiplier_from_list
ewma_span: 125 ## smooth to apply, business day space
div_mult: 2.5 ## maximum allowable multiplier
I've included a smoothing function, otherwise jumps in the multiplier will cause trading in the backtest. Note that the FDM is calculated on an instrument by instrument basis, but if instruments have had their forecast weights and correlations estimated on a pooled basis they'll have the same FDM. It's also a good idea to floor negative correlations at zero to avoid inflating the DM to very high values.
Capital correction is the process by which we change the capital we have at risk, and thus our positions, according to any profits or losses made. Most of pysystemtrade assumes that capital is fixed. This has the advantage that risk is stable over time, and account curves can more easily be interpreted. However a more common method is to use compounded capital, where profits are added to capital and losses deducted. If we make money then our capital, and the risk we're taking, and the size of our positions, will all increase over time.
There is much more in this blog
post.
Capital correction is controlled by the following config parameter which
selects the function used for correction using the normal dot argument (the
default here being the function fixed_capital in the module
syscore.capital)
YAML:
capital_multiplier:
func: syscore.capital.fixed_capital
Other functions I've written are full_compounding and half_compounding.
Again see the blog post blog
post
for more detail.
To get the varying capital multiplier which the chosen method calculates use
system.accounts.capital_multiplier(). The multiplier will be 1.0 at a given
time if the variable capital is identical to the fixed capital.
Here's a list of methods with their counterparts for both fixed and variable capital:
| Fixed capital | Variable capital | |
|---|---|---|
| Get capital at risk | positionSize.get_daily_cash_vol_target()['notional_trading_capital'] |
accounts.get_actual_capital() |
| Get position in a system portfolio | portfolio.get_notional_position |
portfolio.get_actual_position |
| Get buffers for a position | portfolio.get_buffers_for_position |
portfolio.get_actual_buffers_for_position |
| Get buffered position | accounts.get_buffered_position |
accounts.get_buffered_position_with_multiplier |
| Get p&l for instrument at system level | accounts.pandl_for_instrument |
accounts.pandl_for_instrument_with_multiplier |
| P&L for whole system | accounts.portfolio |
accounts.portfolio_with_multiplier |
All other methods in pysystemtrade use fixed capital.
The tables in this section list all the public methods that can be used to get data out of a system and its 'child' stages. You can also use the methods() method:
system.rawdata.methods() ## works for any stage or dataFor brevity the name of the system instance is omitted from the 'call' column
(except where it's the actual system object we're calling directly). So for
example to get the instrument price for Eurodollar from the data object, which
is marked as data.get_raw_price we would do something like this:
from systems.provided.futures_chapter15.basesystem import futures_system
name_of_system=futures_system()
name_of_system.data.get_raw_price("EDOLLAR")Standard methods are in all systems. Non standard methods are for stage classes inherited from the standard class, eg the raw data method specific to futures; or the estimate classes which estimate parameters rather than use fixed versions.
Common arguments are:
instrument_code: A string indicating the name of the instrumentrule_variation_name: A string indicating the name of the trading rule variation
Types are one or more of D, I, O:
- Diagnostic: Exposed method useful for seeing intermediate calculations
- Key Input: A method which gets information from another stage. See stage wiring. The description will list the source of the data.
- Key Output: A method whose output is used by other stages. See stage wiring. Note this excludes items only used by specific trading rules (notably rawdata.daily_annualised_roll)
Private methods are excluded from this table.
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
system.get_instrument_list |
Standard | D,O | List of instruments available; either from config.instrument weights, config.instruments, or from data set |
Other methods exist to access logging and caching.
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
data.get_raw_price |
Standard | instrument_code |
D,O | Intraday prices if available (backadjusted if relevant) |
data.daily_prices |
Standard | instrument_code |
D,O | Default price used for trading rule analysis (backadjusted if relevant) |
data.get_instrument_list |
Standard | D,O | List of instruments available in data set (not all will be used for backtest) | |
data.get_value_of_block_price_move |
Standard | instrument_code |
D,O | How much does a $1 (or whatever) move in the price of an instrument block affect it's value? |
data.get_instrument_currency |
Standard | instrument_code |
D,O | What currency does this instrument trade in? |
data.get_fx_for_instrument |
Standard | instrument_code, base_currency |
D, O | What is the exchange rate between the currency of this instrument, and some base currency? |
data.get_instrument_raw_carry_data |
Futures | instrument_code |
D, O | Returns a dataframe with the 4 columns PRICE, CARRY, PRICE_CONTRACT, CARRY_CONTRACT |
data.get_raw_cost_data |
Standard | instrument_code |
D,O | Cost data (slippage and different types of commission) |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
rawdata.get_daily_prices |
Standard | instrument_code |
I | data.daily_prices |
rawdata.daily_denominator_price |
Standard | instrument_code |
O | Price used to calculate % volatility (for futures the current contract price) |
rawdata.daily_returns |
Standard | instrument_code |
D, O | Daily returns in price units |
rawdata.get_daily_percentage_returns |
Standard | instrument_code |
D | Daily returns as a percentage. |
rawdata.daily_returns_volatility |
Standard | instrument_code |
D,O | Daily standard deviation of returns in price units |
rawdata.get_daily_percentage_volatility |
Standard | instrument_code |
D,O | Daily standard deviation of returns in % (10.0 = 10%) |
rawdata.get_daily_vol_normalised_returns |
Standard | instrument_code |
D | Daily returns normalised by vol (1.0 = 1 sigma) |
rawdata.get_instrument_raw_carry_data |
Futures | instrument_code |
I | data.get_instrument_raw_carry_data |
rawdata.raw_futures_roll |
Futures | instrument_code |
D | The raw difference between price and carry |
rawdata.roll_differentials |
Futures | instrument_code |
D | The annualisation factor |
rawdata.annualised_roll |
Futures | instrument_code |
D | Annualised roll |
rawdata.daily_annualised_roll |
Futures | instrument_code |
D | Annualised roll. Used for carry rule. |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
rules.trading_rules |
Standard | D,O | List of trading rule variations | |
rules.get_raw_forecast |
Standard | instrument_code, rule_variation_name |
D,O | Get forecast (unscaled, uncapped) |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
forecastScaleCap.get_raw_forecast |
Standard | instrument_code, rule_variation_name |
I | rules.get_raw_forecast |
forecastScaleCap.get_forecast_scalar |
Standard / Estimate | instrument_code, rule_variation_name |
D | Get the scalar to use for a forecast |
forecastScaleCap.get_forecast_cap |
Standard | D,O | Get the maximum allowable forecast | |
forecastScaleCap.get_forecast_floor |
Standard | D,O | Get the minimum allowable forecast | |
forecastScaleCap.get_scaled_forecast |
Standard | instrument_code, rule_variation_name |
D | Get the forecast after scaling (after capping) |
forecastScaleCap.get_capped_forecast |
Standard | instrument_code, rule_variation_name |
D, O | Get the forecast after scaling (after capping) |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
combForecast.get_trading_rule_list |
Standard | instrument_code |
I | List of trading rules from config or prior stage |
combForecast.get_all_forecasts |
Standard | instrument_code, (rule_variation_list) |
D | pd.DataFrame of forecast values |
combForecast.get_forecast_cap |
Standard | I | forecastScaleCap.get_forecast_cap |
|
combForecast.calculation_of_raw_estimated_monthly_forecast_weights |
Estimate | instrument_code |
D | Forecast weight calculation objects |
combForecast.get_forecast_weights |
Standard / Estimate | instrument_code |
D | Forecast weights, adjusted for missing forecasts |
combForecast.get_forecast_correlation_matrices |
Estimate | instrument_code |
D | Correlations of forecasts |
combForecast.get_forecast_diversification_multiplier |
Standard / Estimate | instrument_code |
D | Get diversification multiplier |
combForecast.get_combined_forecast |
Standard | instrument_code |
D,O | Get weighted average of forecasts for instrument |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
positionSize.get_combined_forecast |
Standard | instrument_code |
I | combForecast.get_combined_forecast |
positionSize.get_price_volatility |
Standard | instrument_code |
I | rawdata.get_daily_percentage_volatility (or data.daily_prices) |
positionSize.get_underlying_price |
Standard | instrument_code |
I | rawdata.daily_denominator_price (or data.daily_prices); data.get_value_of_block_price_move |
positionSize.get_fx_rate |
Standard | instrument_code |
I | data.get_fx_for_instrument |
positionSize.get_daily_cash_vol_target |
Standard | D | Dictionary of base_currency, percentage_vol_target, notional_trading_capital, annual_cash_vol_target, daily_cash_vol_target | |
positionSize.get_block_value |
Standard | instrument_code |
D | Get value of a 1% move in the price |
positionSize.get_instrument_currency_vol |
Standard | instrument_code |
D | Get daily volatility in the currency of the instrument |
positionSize.get_instrument_value_vol |
Standard | instrument_code |
D | Get daily volatility in the currency of the trading account |
positionSize.get_average_position_at_subsystem_level |
Standard | instrument_code |
D | Get ratio of target volatility vs volatility of instrument in instrument's own currency |
positionSize.get_subsystem_position |
Standard | instrument_code |
D, O | Get position if we put our entire trading capital into one instrument |
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
portfolio.get_subsystem_position |
Standard | instrument_code |
I | positionSize.get_subsystem_position |
portfolio.pandl_across_subsystems |
Estimate | I | accounts.pandl_across_subsystems |
|
portfolio.calculation_of_raw_instrument_weights |
Estimate | D | Instrument weight calculation objects | |
portfolio.get_unsmoothed_instrument_weights_fitted_to_position_lengths |
Standard / Estimate | D | Get raw instrument weights | |
portfolio.get_instrument_weights |
Standard / Estimate | D | Get instrument weights, adjusted for missing instruments | |
portfolio.get_instrument_diversification_multiplier |
Standard / Estimate | D | Get instrument div. multiplier | |
portfolio.get_notional_position |
Standard | instrument_code |
D,O | Get the notional position (with constant risk capital; doesn't allow for adjustments when profits or losses are made) |
portfolio.get_buffers_for_position |
Standard | instrument_code |
D,O | Get the buffers around the position |
portfolio.get_actual_position |
Standard | instrument_code |
D,O | Get position accounting for capital multiplier |
portfolio.get_actual_buffers_for_position |
Standard | instrument_code |
D,O | Get the buffers around the position, accounting for capital multiplier |
Inputs:
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
accounts.get_notional_position |
Standard | instrument_code |
I | portfolio.get_notional_position |
accounts.get_actual_position |
Standard | instrument_code |
I | portfolio.get_actual_position |
accounts.get_capped_forecast |
Standard | instrument_code, rule_variation_name |
I | forecastScaleCap.get_capped_forecast |
accounts.get_instrument_list |
Standard | I | system.get_instrument_list |
|
accounts.get_notional_capital |
Standard | I | positionSize.get_daily_cash_vol_target |
|
accounts.get_fx_rate |
Standard | instrument_code |
I | positionSize.get_fx_rate |
accounts.get_value_of_block_price_move |
Standard | instrument_code |
I | data.get_value_of_block_price_move |
accounts.get_daily_returns_volatility |
Standard | instrument_code |
I | rawdata.daily_returns_volatility or data.daily_prices |
accounts.get_raw_cost_data |
Standard | instrument_code |
I | data.get_raw_cost_data |
accounts.get_buffers_for_position |
Standard | instrument_code |
I | portfolio.get_buffers_for_position |
accounts.get_actual_buffers_for_position |
Standard | instrument_code |
I | portfolio.get_actual_buffers_for_position |
accounts.get_instrument_diversification_multiplier |
Standard | I | portfolio.get_instrument_diversification_multiplier |
|
accounts.get_instrument_weights |
Standard | I | portfolio.get_instrument_weights |
|
accounts.list_of_rules_for_code |
Standard | instrument_code |
I | combForecast.get_trading_rule_list |
accounts.has_same_rules_as_code |
Standard | instrument_code |
I | combForecast.has_same_rules_as_code |
Diagnostics:
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
accounts.list_of_trading_rules |
Standard | D | All trading rules across instruments | |
accounts.get_instrument_scaling_factor |
Standard | instrument_code |
D | IDM * instrument weight |
accounts.get_buffered_position |
Standard | instrument_code |
D | Buffered position at portfolio level |
accounts.get_buffered_position_with_multiplier |
Standard | instrument_code |
D | Buffered position at portfolio level, including capital multiplier |
accounts.subsystem_turnover |
Standard | instrument_code |
D | Annualised turnover of subsystem |
accounts.instrument_turnover |
Standard | instrument_code |
D | Annualised turnover of instrument position at portfolio level |
accounts.forecast_turnover |
Standard | instrument_code, rule_variation_name |
D | Annualised turnover of forecast |
accounts.get_SR_cost_for_instrument_forecast |
Standard | instrument_code, rule_variation_name |
D | SR cost * turnover for forecast |
accounts.capital_multiplier |
Standard | D, O | Capital multiplier, ratio of actual to fixed notional capital | |
accounts.get_actual_capital |
Standard | D | Actual capital (fixed notional capital times multiplier) |
Accounting outputs:
| Call | Standard? | Arguments | Type | Description |
|---|---|---|---|---|
accounts.pandl_for_instrument |
Standard | instrument_code |
D | P&l for an instrument within a system |
accounts.pandl_for_instrument_with_multiplier |
Standard | instrument_code |
D | P&l for an instrument within a system, using multiplied capital |
accounts.pandl_for_instrument_forecast |
Standard | instrument_code, rule_variation_name |
D | P&l for a trading rule and instrument |
accounts.pandl_for_instrument_forecast_weighted |
Standard | instrument_code, rule_variation_name |
D | P&l for a trading rule and instrument as a % of total capital |
accounts.pandl_for_instrument_rules |
Standard | instrument_code |
D,O | P&l for all trading rules in an instrument, weighted |
accounts.pandl_for_instrument_rules_unweighted |
Standard | instrument_code |
D,O | P&l for all trading rules in an instrument, unweighted |
accounts.pandl_for_trading_rule |
Standard | rule_variation_name |
D | P&l for a trading rule over all instruments |
accounts.pandl_for_trading_rule_weighted |
Standard | rule_variation_name |
D | P&l for a trading rule over all instruments as % of total capital |
accounts.pandl_for_trading_rule_unweighted |
Standard | rule_variation_name |
D | P&l for a trading rule over all instruments, unweighted |
accounts.pandl_for_subsystem |
Standard | instrument_code |
D | P&l for an instrument outright |
accounts.pandl_across_subsystems |
Standard | instrument_code |
O,D | P&l across instruments, outright |
accounts.pandl_for_all_trading_rules |
Standard | D | P&l for trading rules across whole system | |
accounts.pandl_for_all_trading_rules_unweighted |
Standard | D | P&l for trading rules across whole system | |
accounts.portfolio |
Standard | O,D | P&l for whole system | |
accounts.portfolio_with_multiplier |
Standard | D | P&l for whole system using multiplied capital |
Below is a list of all configuration options for the system. The 'Yaml' section shows how they appear in a yaml file. The 'python' section shows an example of how you'd modify a config object in memory having first created it, like this:
## Method one: from an existing system
from systems.provided.futures_chapter15.basesystem import futures_system
system=futures_system()
new_config=system.config
## Method two: from a config file
from syscore.fileutils import get_pathname_for_package
from sysdata.config.configdata import Config
my_config=Config(get_pathname_for_package("private", "this_system_name", "config.yaml"))
## Method three: with a blank config
from sysdata.config.configdata import Config
my_config=Config()Each section also shows the project default options, which you could change here.
When modifying a nested part of a config object, you can of course replace it wholesale:
new_config.instrument_weights=dict(SP500=0.5, US10=0.5))
new_configOr just in part:
new_config.instrument_weights['SP500']=0.2
new_configIf you do this make sure the rest of the config is consistent with what you've done. In either case, it's a good idea to examine the modified config once it's part of the system (since that will include any defaults) and make sure you're happy with it.
Represented as: dict of str, int, or float. Keywords: Parameter names Defaults: As below
The function used to calculate volatility, and any keyword arguments passed to it. Note if any keyword is missing then the project defaults will be used. See 'volatility calculation' for more information.
The following shows how to modify the configuration, and also the default values:
YAML:
volatility_calculation:
func: "sysquant.estimators.vol.robust_vol_calc"
days: 35
min_periods: 10
vol_abs_min: 0.0000000001
vol_floor: True
floor_min_quant: 0.05
floor_min_periods: 100
floor_days: 500
Python
config.volatility_calculation=dict(func="syscore.algos.robust.vol.calc", days=35, min_periods=10, vol_abs_min= 0.0000000001, vol_floor=True, floor_min_quant=0.05, floor_min_periods=100, floor_days=500)If you're considering using your own function please see configuring defaults for your own functions
Represented as: dict of dicts, each representing a trading rule. Keywords: trading rule variation names. Defaults: n/a
The set of trading rules. A trading rule definition consists of a dict containing: a function identifying string, an optional list of data identifying strings, and other_args an optional dictionary containing named parameters to be passed to the function. This is the only method that can be used for YAML.
There are numerous other ways to define trading rules using python code. See 'Rules' for more detail.
Note that forecast_scalar isn't strictly part of the trading rule definition, but if included here will be used instead of the separate 'config.forecast_scalar' parameter (see the next section).
YAML: (example)
trading_rules:
ewmac2_8:
function: systems.futures.rules.ewmac
data:
- "rawdata.daily_prices"
- "rawdata.daily_returns_volatility"
other_args:
Lfast: 2
Lslow: 8
forecast_scalar: 10.6
Python (example)
config.trading_rules=dict(ewmac2_8=dict(function="systems.futures.rules.ewmac", data=["rawdata.daily_prices", "rawdata.daily_returns_volatility"], other_args=dict(Lfast=2, Lslow=8), forecast_scalar=10.6))Switch between fixed (default) and estimated versions as follows:
YAML: (example)
use_forecast_scale_estimates: True
Python (example)
config.use_forecast_scale_estimates=TrueRepresented as: dict of floats. Keywords: trading rule variation names. Default: 1.0
The forecast scalar to apply to a trading rule, if fixed scaling is being used. If undefined the default value of 1.0 will be used.
Scalars can also be put inside trading rule definitions (this is the first place we look):
YAML: (example)
trading_rules:
rule_name:
function: systems.futures.rules.arbitrary_function
forecast_scalar: 10.6
Python (example)
config.trading_rules=dict(rule_name=dict(function="systems.futures.rules.arbitrary_function", forecast_scalar=10.6))If scalars are not found there they can be put in separately (if you do both then the scalar in the actual rule specification will take precedence):
YAML: (example)
forecast_scalars:
rule_name: 10.6
Python (example)
config.forecast_scalars=dict(rule_name=10.6)Represented as: dict of str, float and int. Keywords: parameter names Default: see below
The method used to estimate forecast scalars on a rolling out of sample basis. Any missing config elements are pulled from the project defaults. Compulsory arguments are pool_instruments (determines if we pool estimate over multiple instruments) and func (str function pointer to use for estimation). The remaining arguments are passed to the estimation function.
See forecast scale estimation for more detail.
If you're considering using your own function please see configuring defaults for your own functions
YAML:
# Here is how we do the estimation. These are also the *defaults*.
use_forecast_scale_estimates: True
forecast_scalar_estimate:
pool_instruments: True
func: "sysquant.estimators.forecast_scalar.forecast_scalar"
window: 250000
min_periods: 500
backfill: True
Python (example)
## pooled example
config.trading_rules=dict(pool_instruments=True, func="sysquant.estimators.forecast_scalar.forecast_scalar", window=250000, min_periods=500, backfill=True)Represented as: float
The forecast cap to apply to a trading rule. If undefined the project default value of 20.0 will be used.
YAML:
forecast_cap: 20.0
Python
config.forecast_cap=20.0Switch between fixed (default) and estimated versions as follows:
YAML: (example)
use_forecast_weight_estimates: True
Python (example)
config.use_forecast_weight_estimates=TrueChange smoothing used for both fixed and variable weights:
YAML: (example)
forecast_weight_ewma_span: 6
Remove trading rules which are too expensive for a given instrument:
YAML: (example)
post_ceiling_cost_SR: 0.13
Represented as: (a) dict of floats. Keywords: trading rule variation names. (b) dict of dicts, each representing the weights for an instrument. Keywords: instrument names Default: Equal weights, across all trading rules in the system
The forecast weights to be used to combine forecasts from different trading rule variations. These can be (a) common across instruments, or (b) specified differently for each instrument.
Notice that the default is equal weights, but these are calculated on the fly and don't appear in the defaults file.
YAML: (a)
forecast_weights:
ewmac: 0.50
carry: 0.50
Python (a)
config.forecast_weights=dict(ewmac=0.5, carry=0.5)YAML: (b)
forecast_weights:
SP500:
ewmac: 0.50
carry: 0.50
US10:
ewmac: 0.10
carry: 0.90
Python (b)
config.forecast_weights=dict(SP500=dict(ewmac=0.5, carry=0.5), US10=dict(ewmac=0.10, carry=0.90))To estimate forecast weights we need to define which trading rule variations we're using.
Represented as: (a) list of str, each a rule variation name (b) dict of list of str, each representing the rules for an instrument. Keywords: instrument names Default: Using all trading rules in the system
The rules for which forecast weights are to be calculated. These can be (a) common across instruments, or (b) specified differently for each instrument. If not specified will use all the rules defined in the system.
YAML: (a)
rule_variations:
- "ewmac"
- "carry"
Python (a)
config.rule_variations=["ewmac", "carry"]YAML: (b)
rule_variations:
SP500:
- "ewmac"
- "carry"
US10:
- "ewmac"
Python (b)
config.forecast_weights=dict(SP500=["ewmac","carry"], US10=["ewmac"])See the section on Optimisation
Represented as: (a) float or (b) dict of floats with keywords: instrument_codes Default: 1.0
This can be (a) common across instruments, or (b) we use a different one for each instrument (would be normal if instrument weights were also different).
YAML: (a)
forecast_div_multiplier: 1.0
Python (a)
config.forecast_div_multiplier=1.0YAML: (b)
forecast_div_multiplier:
SP500: 1.4
US10: 1.1
Python (b)
config.forecast_div_multiplier=dict(SP500=1.4, US10=1.0)See the section on estimating correlations and diversification multipliers
Represented as: dict (key names instrument names) of dict (key names: a_param,b_param, threshold). Defaults: dict(a_param = 1.0, b_param = 1.0, threshold = 0.0) equivalent to no mapping
YAML, showing defaults
forecast_mapping:
AUD:
a_param: 1.0
b_param: 1.0
threshold: 0.0
# etc
Python, example of how to change certain parameters:
config.forecast_mapping = dict()
config.forecast_maping['AUD'] = dict(a_param=1.0, b_param=1.0, threshold = 0.0)
config.forecast_maping['AUD']['a_param'] = 1.0Represented as: floats, int or str Defaults: See below
The annualised percentage volatility target, notional trading capital and currency of trading capital. If any of these are undefined in the config the default values shown below will be used.
YAML:
percentage_vol_target: 16.0
notional_trading_capital: 1000000
base_currency: "USD"
Python
config.percentage_vol_target=16.0
config.notional_trading_capital=1000000
config.base_currency="USD"Switch between fixed (default) and estimated versions as follows:
YAML: (example)
use_instrument_weight_estimates: True
Python (example)
config.use_instrument_weight_estimates=TrueChange smoothing used for both fixed and variable weights:
YAML: (example)
instrument_weight_ewma_span: 125
Represented as: dict of floats. Keywords: instrument_codes Default: Equal weights
The instrument weights used to combine different instruments together into the final portfolio.
Although the default is equal weights, these are not included in the system defaults file, but calculated on the fly.
YAML:
instrument_weights:
EDOLLAR: 0.5
US10: 0.5
Python
config.instrument_weights=dict(EDOLLAR=0.5, US10=0.5)See the section on Optimisation
Represented as: float Default: 1.0
YAML:
instrument_div_multiplier: 1.0
Python
config.instrument_div_multiplier=1.0See the section on estimating correlations and diversification multipliers
Represented as: bool Default: see below
Which buffering or position inertia method should we use? 'position': based on optimal position (position inertia), 'forecast': based on position with a forecast of +10; or 'none': do not use a buffer. What size should the buffer be, as a proportion of the position or average forecast position? 0.1 is 10%.
YAML:
buffer_method: position
buffer_size: 0.10
To work out the portfolio positions should we trade to the edge of the buffer, or to the optimal position?
Represented as: bool Default: True
YAML:
buffer_trade_to_edge: True
Should we use normalised Sharpe Ratio costs, or the actual costs for instrument level p&l (we always use SR costs for forecasts)?
YAML:
use_SR_costs: True
Should we pool SR costs across instruments when working out forecast p&L?
YAML:
forecast_cost_estimate:
use_pooled_costs: False ### use weighted average of SR cost * turnover across instruments with the same set of trading rules
use_pooled_turnover: True ### Use weighted average of turnover across instruments with the same set of trading rules
Which capital correction method should we use?
YAML:
capital_multiplier:
func: syscore.capital.fixed_capital
Other valid functions include full_compounding and half_compounding.