Add urban_meal_delivery.forecasts.models sub-package

- `*Model`s use the `methods.*.predict()` functions to predict demand
  given an order time series generated by `timify.OrderHistory`
- `models.base.ForecastingModelABC` unifies how all `*Model`s work
  and implements a caching strategy
- implement three `*Model`s for tactical forecasting, based on the
  hets, varima, and rtarima models described in the first research paper
- add overall documentation for `urban_meal_delivery.forecasts` package
- move the fixtures in `tests.forecasts.timify.conftest` to
  `tests.forecasts.conftest` and adjust the horizon of the test horizon
  from two to three weeks
This commit is contained in:
Alexander Hess 2021-02-01 20:39:52 +01:00
commit 67cd58cf16
Signed by: alexander
GPG key ID: 344EA5AB10D868E0
12 changed files with 747 additions and 71 deletions

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@ -1,4 +1,4 @@
"""Fixtures and globals for testing `urban_meal_delivery.forecasts`."""
"""Fixtures for testing the `urban_meal_delivery.forecasts` sub-package."""
import datetime as dt
@ -7,6 +7,7 @@ import pytest
from tests import config as test_config
from urban_meal_delivery import config
from urban_meal_delivery.forecasts import timify
@pytest.fixture
@ -28,7 +29,10 @@ def horizontal_datetime_index():
index = pd.Index(gen)
index.name = 'start_at'
assert len(index) == 15 # sanity check
# Sanity check.
# `+1` as both the `START` and `END` day are included.
n_days = (test_config.END - test_config.START).days + 1
assert len(index) == n_days
return index
@ -58,7 +62,10 @@ def vertical_datetime_index():
index = pd.Index(gen)
index.name = 'start_at'
assert len(index) == 15 * 12 # sanity check
# Sanity check: n_days * n_number_of_opening_hours.
# `+1` as both the `START` and `END` day are included.
n_days = (test_config.END - test_config.START).days + 1
assert len(index) == n_days * 12
return index
@ -67,3 +74,54 @@ def vertical_datetime_index():
def vertical_no_demand(vertical_datetime_index):
"""A vertical time series with order totals: no demand."""
return pd.Series(0, index=vertical_datetime_index, name='n_orders')
@pytest.fixture
def good_pixel_id(pixel):
"""A `pixel_id` that is on the `grid`."""
return pixel.id # `== 1`
@pytest.fixture
def order_totals(good_pixel_id):
"""A mock for `OrderHistory.totals`.
To be a bit more realistic, we sample two pixels on the `grid`.
Uses the LONG_TIME_STEP as the length of a time step.
"""
pixel_ids = [good_pixel_id, good_pixel_id + 1]
gen = (
(pixel_id, start_at)
for pixel_id in pixel_ids
for start_at in pd.date_range(
test_config.START, test_config.END, freq=f'{test_config.LONG_TIME_STEP}T',
)
if config.SERVICE_START <= start_at.hour < config.SERVICE_END
)
# Re-index `data` filling in `0`s where there is no demand.
index = pd.MultiIndex.from_tuples(gen)
index.names = ['pixel_id', 'start_at']
df = pd.DataFrame(data={'n_orders': 1}, index=index)
# Sanity check: n_pixels * n_time_steps_per_day * n_days.
# `+1` as both the `START` and `END` day are included.
n_days = (test_config.END - test_config.START).days + 1
assert len(df) == 2 * 12 * n_days
return df
@pytest.fixture
def order_history(order_totals, grid):
"""An `OrderHistory` object that does not need the database.
Uses the LONG_TIME_STEP as the length of a time step.
"""
oh = timify.OrderHistory(grid=grid, time_step=test_config.LONG_TIME_STEP)
oh._data = order_totals
return oh

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@ -0,0 +1,181 @@
"""Tests for the `urban_meal_delivery.forecasts.models` sub-package."""
import datetime as dt
import pandas as pd
import pytest
from tests import config as test_config
from urban_meal_delivery import db
from urban_meal_delivery.forecasts import models
MODELS = (
models.HorizontalETSModel,
models.RealtimeARIMAModel,
models.VerticalARIMAModel,
)
@pytest.mark.parametrize('model_cls', MODELS)
class TestGenericForecastingModelProperties:
"""Test everything all concrete `*Model`s have in common.
The test cases here replace testing the `ForecastingModelABC` class on its own.
As uncertainty is in the nature of forecasting, we do not test the individual
point forecasts or confidence intervals themselves. Instead, we confirm
that all the `*Model`s adhere to the `ForecastingModelABC` generically.
So, these test cases are more like integration tests conceptually.
Also, note that some `methods.*.predict()` functions use R behind the scenes.
""" # noqa:RST215
def test_create_model(self, model_cls, order_history):
"""Test instantiation of a new and concrete `*Model` object."""
model = model_cls(order_history=order_history)
assert model is not None
def test_model_has_a_name(self, model_cls, order_history):
"""Access the `*Model.name` property."""
model = model_cls(order_history=order_history)
result = model.name
assert isinstance(result, str)
unique_model_names = set()
def test_each_model_has_a_unique_name(self, model_cls, order_history):
"""The `*Model.name` values must be unique across all `*Model`s.
Important: this test case has a side effect that is visible
across the different parametrized versions of this case!
""" # noqa:RST215
model = model_cls(order_history=order_history)
assert model.name not in self.unique_model_names
self.unique_model_names.add(model.name)
@pytest.fixture
def predict_at(self) -> dt.datetime:
"""`NOON` on the day to be predicted."""
return dt.datetime(
test_config.END.year,
test_config.END.month,
test_config.END.day,
test_config.NOON,
)
@pytest.mark.r
def test_make_prediction_structure(
self, model_cls, order_history, pixel, predict_at,
):
"""`*Model.predict()` returns a `pd.DataFrame` ...
... with known columns.
""" # noqa:RST215
model = model_cls(order_history=order_history)
result = model.predict(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
assert isinstance(result, pd.DataFrame)
assert list(result.columns) == [
'actual',
'prediction',
'low80',
'high80',
'low95',
'high95',
]
@pytest.mark.r
def test_make_prediction_for_given_time_step(
self, model_cls, order_history, pixel, predict_at,
):
"""`*Model.predict()` returns a row for ...
... the time step starting at `predict_at`.
""" # noqa:RST215
model = model_cls(order_history=order_history)
result = model.predict(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
assert predict_at in result.index
@pytest.mark.r
def test_make_prediction_contains_actual_values(
self, model_cls, order_history, pixel, predict_at,
):
"""`*Model.predict()` returns a `pd.DataFrame` ...
... where the "actual" and "prediction" columns must not be empty.
""" # noqa:RST215
model = model_cls(order_history=order_history)
result = model.predict(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
assert not result['actual'].isnull().any()
assert not result['prediction'].isnull().any()
@pytest.mark.db
@pytest.mark.r
def test_make_forecast( # noqa:WPS211
self, db_session, model_cls, order_history, pixel, predict_at,
):
"""`*Model.make_forecast()` returns a `Forecast` object.""" # noqa:RST215
model = model_cls(order_history=order_history)
result = model.make_forecast(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
assert isinstance(result, db.Forecast)
assert result.pixel == pixel
assert result.start_at == predict_at
assert result.training_horizon == test_config.LONG_TRAIN_HORIZON
@pytest.mark.db
@pytest.mark.r
def test_make_forecast_is_cached( # noqa:WPS211
self, db_session, model_cls, order_history, pixel, predict_at,
):
"""`*Model.make_forecast()` caches the `Forecast` object.""" # noqa:RST215
model = model_cls(order_history=order_history)
assert db_session.query(db.Forecast).count() == 0
result1 = model.make_forecast(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
n_cached_forecasts = db_session.query(db.Forecast).count()
assert n_cached_forecasts >= 1
result2 = model.make_forecast(
pixel=pixel,
predict_at=predict_at,
train_horizon=test_config.LONG_TRAIN_HORIZON,
)
assert n_cached_forecasts == db_session.query(db.Forecast).count()
assert result1 == result2

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@ -1,57 +0,0 @@
"""Fixture for testing the `urban_meal_delivery.forecast.timify` module."""
import pandas as pd
import pytest
from tests import config as test_config
from urban_meal_delivery import config
from urban_meal_delivery.forecasts import timify
@pytest.fixture
def good_pixel_id(pixel):
"""A `pixel_id` that is on the `grid`."""
return pixel.id # `== 1`
@pytest.fixture
def order_totals(good_pixel_id):
"""A mock for `OrderHistory.totals`.
To be a bit more realistic, we sample two pixels on the `grid`.
Uses the LONG_TIME_STEP as the length of a time step.
"""
pixel_ids = [good_pixel_id, good_pixel_id + 1]
gen = (
(pixel_id, start_at)
for pixel_id in pixel_ids
for start_at in pd.date_range(
test_config.START, test_config.END, freq=f'{test_config.LONG_TIME_STEP}T',
)
if config.SERVICE_START <= start_at.hour < config.SERVICE_END
)
# Re-index `data` filling in `0`s where there is no demand.
index = pd.MultiIndex.from_tuples(gen)
index.names = ['pixel_id', 'start_at']
df = pd.DataFrame(data={'n_orders': 1}, index=index)
# Sanity check: n_pixels * n_time_steps_per_day * n_weekdays * n_weeks.
assert len(df) == 2 * 12 * (7 * 2 + 1)
return df
@pytest.fixture
def order_history(order_totals, grid):
"""An `OrderHistory` object that does not need the database.
Uses the LONG_TIME_STEP as the length of a time step.
"""
oh = timify.OrderHistory(grid=grid, time_step=test_config.LONG_TIME_STEP)
oh._data = order_totals
return oh

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@ -17,8 +17,8 @@ from urban_meal_delivery import config
def good_predict_at():
"""A `predict_at` within `START`-`END` and ...
... a long enough history so that either `train_horizon=1`
or `train_horizon=2` works.
... a long enough history so that either `SHORT_TRAIN_HORIZON`
or `LONG_TRAIN_HORIZON` works.
"""
return datetime.datetime(
test_config.END.year,
@ -33,10 +33,10 @@ def good_predict_at():
def bad_predict_at():
"""A `predict_at` within `START`-`END` but ...
... not a long enough history so that both `train_horizon=1`
and `train_horizon=2` do not work.
... not a long enough history so that both `SHORT_TRAIN_HORIZON`
and `LONG_TRAIN_HORIZON` do not work.
"""
predict_day = test_config.END - datetime.timedelta(weeks=1, days=1)
predict_day = test_config.END - datetime.timedelta(weeks=2, days=1)
return datetime.datetime(
predict_day.year, predict_day.month, predict_day.day, test_config.NOON, 0,
)