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b976c1252b
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
141 lines
5.0 KiB
Python
141 lines
5.0 KiB
Python
#
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# Copyright 2012 Quantopian, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import unittest
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import datetime
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import pytz
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import numpy as np
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import zipline.finance.risk as risk
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from zipline.utils import factory
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from zipline.finance.trading import TradingEnvironment
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from test_risk import RETURNS
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class RiskCompareIterativeToBatch(unittest.TestCase):
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"""
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Assert that RiskMetricsIterative and RiskMetricsBatch
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behave in the same way.
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"""
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def setUp(self):
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self.start_date = datetime.datetime(
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year=2006,
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month=1,
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day=1,
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hour=0,
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minute=0,
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tzinfo=pytz.utc)
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self.end_date = datetime.datetime(
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year=2006, month=12, day=31, tzinfo=pytz.utc)
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self.benchmark_returns, self.treasury_curves = \
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factory.load_market_data()
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self.trading_env = TradingEnvironment(
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self.benchmark_returns,
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self.treasury_curves,
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period_start=self.start_date,
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period_end=self.end_date,
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capital_base=1000.0
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)
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self.oneday = datetime.timedelta(days=1)
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def test_risk_metrics_returns(self):
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risk_metrics_refactor = risk.RiskMetricsIterative(
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self.start_date, self.trading_env)
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todays_date = self.start_date
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cur_returns = []
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for i, ret in enumerate(RETURNS):
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todays_return_obj = risk.DailyReturn(
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todays_date,
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ret
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)
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cur_returns.append(todays_return_obj)
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try:
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risk_metrics_original = risk.RiskMetricsBatch(
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start_date=self.start_date,
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end_date=todays_date + self.oneday,
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returns=cur_returns,
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trading_environment=self.trading_env
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)
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except Exception as e:
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#assert that when original raises exception, same
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#exception is raised by risk_metrics_refactor
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np.testing.assert_raises(
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type(e), risk_metrics_refactor.update, ret, self.oneday)
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continue
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risk_metrics_refactor.update(ret, self.oneday)
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todays_date += self.oneday
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self.assertEqual(
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risk_metrics_original.start_date,
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risk_metrics_refactor.start_date)
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self.assertEqual(
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risk_metrics_original.end_date,
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risk_metrics_refactor.end_date)
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self.assertEqual(
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risk_metrics_original.treasury_duration,
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risk_metrics_refactor.treasury_duration)
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self.assertEqual(
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risk_metrics_original.treasury_curve,
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risk_metrics_refactor.treasury_curve)
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self.assertEqual(
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risk_metrics_original.treasury_period_return,
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risk_metrics_refactor.treasury_period_return)
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self.assertEqual(
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risk_metrics_original.benchmark_returns,
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risk_metrics_refactor.benchmark_returns)
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self.assertEqual(
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risk_metrics_original.algorithm_returns,
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risk_metrics_refactor.algorithm_returns)
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risk_original_dict = risk_metrics_original.to_dict()
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risk_refactor_dict = risk_metrics_refactor.to_dict()
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self.assertEqual(set(risk_original_dict.keys()),
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set(risk_refactor_dict.keys()))
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err_msg_format = \
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"In update step {iter}: {measure} should be {truth} but is {returned}!"
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for measure in risk_original_dict.iterkeys():
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if measure == 'max_drawdown':
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np.testing.assert_almost_equal(
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risk_refactor_dict[measure],
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risk_original_dict[measure],
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err_msg=err_msg_format.format(
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iter=i,
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measure=measure,
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truth=risk_original_dict[measure],
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returned=risk_refactor_dict[measure]))
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else:
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np.testing.assert_equal(
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risk_original_dict[measure],
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risk_refactor_dict[measure],
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err_msg_format.format(
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iter=i,
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measure=measure,
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truth=risk_original_dict[measure],
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returned=risk_refactor_dict[measure])
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)
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