- Create different benchmark containers in performance
depending on emission rate.
- Add a minute close method which updates algorithm and
benchmark returns, and calculates the risk metrics
depending on those methods.
- Provide fake 0.0 values for annualized metrics like
sharpe, sortino, and information, until we figure out
how they should be treated in the context of minutely
calculation.
*NOTE* This does not fully work without the changes to the
simulation loop by @fawce
The use of np.allclose introduced a severe performance penalty,
caused by the creation of two `np.array`s for each check.
Instead create and use a similar check which maintains tolerance
to floating point rounding, but operates only on scalars.
eigen vales, covariance, etc. are not calculated until the first
return is passed through, so initialize this values to None, so that
`repr` and its ilk work on a freshly created `RiskMetricsIterative`
object.
So that calculations that leverage the range of the treasury_curves,
like `pd.Series.searchsorted` will not overshoot the 'end' of the
range we are calculating risk metrics.
The treasury_duration member in RiskMetrics is never used except
for in unit tests.
Remove the saving of treasury_duration in preparation for the
move of the choose_treasury method out of the RiskMetrics classes.
Down the line, if we do restore the sanving of treasury_duration,
choose_treasury can return a tuple that includes treasury_duration
instead of just returning the rate.
To make the risk metrics being calculated more clear, change the
naming convention that ratios have a '_risk' suffix.
Also, fixes typo in beta docstring.
Move the risk metric definitions to functions at the module level
with defined parameters.
Both risk implementations call these functions, where the difference
between risk implementations is with which internal data they
send to the various risk metrics.
Metrics moved:
- Sharpe Ratio
- Sortino Ratio
- Information Ration
- Alpha
Following the lead of the RiskMetricsBatch conversion to use
more pandas and numpy.
Bringing the iterative and batch versions closer together as we
work towards folding them into one.
- added LSE reference rrules calendar (thanks to Edward Johns)
- added tests to verify LSE environment matches rrule calendar
- added a test to verify global environment behavior can be set.
- moved DailyReturn class to trading to eliminate circularity from
risk <-> trading.
- updated TradingEnvironment to be a context manager. This allows users
to run algorithms in individually isolated environments in one python
process. This is useful for managing multiple algorithms in a single
ipython notebook.
- added comments to explain behavior and useage of the global environment
Global state for the financial simulation environment is accessed through the
zipline.finance.trading module, which now contains a module variable:
environment.
Parameters are passed into an algorithm as a keyword argument, sim_params.
SimulationParameters creates a trading day index for the test period that
can be used to find trading days, calculate distance between trading days,
and other common operations. The sim params index is just selected from the
global state.
================
Details:
- adding delorean to the requirements.
- made index symbol a parameter for loading the benchmark data. changed
messagepack storage to be symbol specific.
- ported risk, performance, algorithm, transforms, batch transforms
and associated tests to use simulation parameters and global environment
- factory and sim factory use global state and sim params
- factory method parameter names now reflect the class expected
To handle, for instance, Columbus Day (Oct 10),
on which there is no treasury data.
We're only forward-filling data now, and
no longer searching both back and forward in time.
Updated the search for treasury data when there is none for the
test end date.
It could be that the end date is not a trading day, or we could
just be missing treasury data. In either case, we try to recover
more gracefully now, by searching as far as possible and maybe
logging a warning.
Similarly, if there is no benchmark data for the test end date,
look for the next trading day. If we really have no data,
blow up with our own explicit exception, instead of overflowing
in our search for dates in the future.
We were only incrementing the risk report by one day, and never
checking to see if that day we incremented into was a trading day
or not.
We now increment by day until we are on a trading day.
With an assist from @twiecki on:
Adapted test_risk_compare_batch_iterative to work with fixed
iterative risk class.
The latest flake8 release in now 1.5, which pulls in pep8: 1.3.4a0
The upgrade pep8 has changes to what it picks up as lint.
Making code base compatible, so that new devs can install pep8
from PyPI and not have friction over the version difference.
Currently using these ignores in the config file:
```
[pep8]
ignore = E124,E125,E126
```
Ignoring these since they are difficult to squash while maintaining
an 80 char line length, and appear spurious.
Should address later.
Updates Travis config, README, and pip requirements to reflect change.
I wrote this a little while ago as I noticed that a lot of time is spent
computing risk statistics. This is done over the complete history over
and over again while this could be done just by using the previously
computed value (iteratively).
We didn't go forward back then because for minute trade data the
difference was not significant enough. However, now with zipline
standalone I think most people will use daily (because that's
what's available) and it makes a huge difference
(speed-up of a couple of 100%).
Unfortunately, we can't just replace the existing one with an
iterative as for the final cumulative stats the batch is still
better. So that's not as nice, but the performance increase is
big enough for me to issue this PR (zipline is actually painfully
slow with daily data).
There is a unittest that compares that both produce exactly
the same outputs.
Speed measurements (for 500 trading days, daily source):
with iterative:
real 26.617 user 12.909 sys 6.112 pcpu 71.46
prior:
real 44.176 user 31.030 sys 11.381 pcpu 96.00
Mostly whitespace, line width and other spacing changes.
Also, removes use of deprecated has_key in favor of `in`
Going forward new patches should pass running `flake8` before
submission.
Eddie Hebert