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111 lines
2.8 KiB
111 lines
2.8 KiB
import datetime
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import math
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import random
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from typing import List
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import pytest
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from dateutil.relativedelta import relativedelta
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import pyfacts as pft
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def conf_add(n1, n2):
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return n1 + n2
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@pytest.fixture
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def conf_fun():
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return conf_add
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def create_prices(s0: float, mu: float, sigma: float, num_prices: int) -> list:
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"""Generates a price following a geometric brownian motion process based on the input of the arguments.
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Since this function is used only to generate data for tests, the seed is fixed as 1234.
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Many of the tests rely on exact values generated using this seed.
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If the seed is changed, those tests will fail.
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Parameters:
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------------
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s0: float
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Asset inital price.
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mu: float
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Interest rate expressed annual terms.
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sigma: float
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Volatility expressed annual terms.
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num_prices: int
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number of prices to generate
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Returns:
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--------
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Returns a list of values generated using GBM algorithm
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"""
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random.seed(1234) # WARNING! Changing the seed will cause most tests to fail
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all_values = []
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for _ in range(num_prices):
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s0 *= math.exp(
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(mu - 0.5 * sigma**2) * (1.0 / 365.0) + sigma * math.sqrt(1.0 / 365.0) * random.gauss(mu=0, sigma=1)
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)
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all_values.append(round(s0, 2))
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return all_values
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def sample_data_generator(
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frequency: pft.Frequency,
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start_date: datetime.date = datetime.date(2017, 1, 1),
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num: int = 1000,
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skip_weekends: bool = False,
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mu: float = 0.1,
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sigma: float = 0.05,
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eomonth: bool = False,
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dates_as_string: bool = False,
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) -> List[tuple]:
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"""Creates TimeSeries data
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Parameters:
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-----------
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frequency: Frequency
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The frequency of the time series data to be generated.
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num: int
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Number of date: value pairs to be generated.
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skip_weekends: bool
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Whether weekends (saturday, sunday) should be skipped.
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Gets used only if the frequency is daily.
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mu: float
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Mean return for the values.
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sigma: float
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standard deviation of the values.
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Returns:
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--------
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Returns a TimeSeries object
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"""
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timedelta_dict = {
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frequency.freq_type: int(
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frequency.value * num * (7 / 5 if frequency == pft.AllFrequencies.D and skip_weekends else 1)
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)
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}
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end_date = start_date + relativedelta(**timedelta_dict)
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dates = pft.create_date_series(
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start_date, end_date, frequency.symbol, skip_weekends=skip_weekends, eomonth=eomonth, ensure_coverage=False
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)
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if dates_as_string:
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dates = [dt.strftime("%Y-%m-%d") for dt in dates]
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values = create_prices(1000, mu, sigma, num)
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ts = list(zip(dates, values))
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return ts
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@pytest.fixture
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def create_test_data():
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return sample_data_generator
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