def test_predict_score_df():
"""Tests _PredictScorerDF by checking whether it can
properly score a DummyEstimator
"""
periods = 20
model = DummyEstimator()
X = pd.DataFrame({
TIME_COL: pd.date_range("2018-01-01", periods=periods, freq="D"),
VALUE_COL: np.arange(periods) # the first value is 0, so MAPE will divide by 0
})
model.fit(X)
def method_caller(estimator, method, *args, **kwargs):
"""Call estimator with method and args and kwargs."""
return getattr(estimator, method)(*args, **kwargs)
with pytest.warns(Warning, match="Score is undefined for this split, setting to `np.nan`."):
scorer = _PredictScorerDF(mean_absolute_percent_error, 1, {})
score = scorer._score(method_caller, model, X, X[VALUE_COL])
assert np.isnan(score)
scorer = _PredictScorerDF(mean_absolute_percent_error, -1, {})
score = scorer._score(method_caller, model, X, X[VALUE_COL])
assert np.isnan(score)
scorer = _PredictScorerDF(mean_absolute_error, -1, {})
score = scorer._score(method_caller, model, X, X[VALUE_COL])
model.predict(X)
assert score == -5.0 # MAE of 9.5 vs [0, 1, 2, ..., 19]
def test_score():
"""Tests score function"""
model = DummyEstimator(strategy="mean", score_func=mean_absolute_error)
X = pd.DataFrame({
TIME_COL:
pd.date_range("2018-01-01", periods=3, freq="1D"),
VALUE_COL: [2.0, 3.0, 4.0]
})
model.fit(X) # prediction is 3.0
y = pd.Series([1.0, 2.0, 3.0])
assert model.score(X, y) == mean_absolute_error(y,
np.repeat(3.0, X.shape[0]))
def test_quantile_model():
"""Tests quantile model with custom column names"""
model = DummyEstimator(strategy="quantile", quantile=0.8)
X = pd.DataFrame({
"time_name":
pd.date_range("2018-01-01", periods=11, freq="D"),
"value_name":
np.arange(11)
})
model.fit(X, time_col="time_name", value_col="value_name")
predicted = model.predict(X)
expected = pd.DataFrame({
TIME_COL: X["time_name"],
PREDICTED_COL: np.repeat(8.0, X.shape[0])
})
assert predicted.equals(expected)
def test_constant_model():
"""Tests constant model"""
constant = 1.0
model = DummyEstimator(strategy="constant", constant=constant)
X = pd.DataFrame({
TIME_COL:
pd.date_range("2018-01-01", periods=3, freq="1D"),
VALUE_COL: [2, 3, 4]
})
model.fit(X)
predicted = model.predict(X)
expected = pd.DataFrame({
TIME_COL: X[TIME_COL],
PREDICTED_COL: np.repeat(constant, X.shape[0])
})
assert predicted.equals(expected)
def test_fit_predict1():
"""Tests sample_weight parameter and different train/test set"""
model = DummyEstimator()
X = pd.DataFrame({
TIME_COL:
pd.date_range("2018-01-01", periods=3, freq="1D"),
VALUE_COL: [2, 3, 5]
})
df_test = pd.DataFrame(
{TIME_COL: pd.date_range("2018-01-01", periods=4, freq="1D")})
model.fit(X, sample_weight=[1, 1, 2])
predicted = model.predict(df_test)
expected = pd.DataFrame({
TIME_COL: df_test[TIME_COL],
PREDICTED_COL: np.repeat(3.75, df_test.shape[0])
})
assert predicted.equals(expected)
def test_pipeline_union(X, fs):
"""Tests PandasFeatureUnion on a pipeline of transformers and estimator, and shows
that null model extracted from estimator in pipeline is equivalent to null model trained
directly"""
model_estimator = Pipeline([
("input", fs),
("estimator", SimpleSilverkiteEstimator(score_func=mean_squared_error,
coverage=0.80,
null_model_params={"strategy": "mean"}))
])
# fits pipeline with estimator, and extract dummy null model
z_cutoff = 2.0
model_estimator.set_params(input__response__outlier__z_cutoff=z_cutoff)
model_estimator.fit(X)
output_estimator_null = model_estimator.steps[-1][-1].null_model.predict(X)
# fits pipeline with dummy estimator
model_dummy = Pipeline([
("input", fs),
("dummy", DummyEstimator(score_func=mean_squared_error, strategy="mean"))
])
model_dummy.fit(X)
output_dummy = model_dummy.predict(X)
# fits dummy estimator by hand, without Pipeline
X_after_column_select = ColumnSelector([VALUE_COL]).fit_transform(X)
X_after_z_score = ZscoreOutlierTransformer(z_cutoff=z_cutoff).fit_transform(X_after_column_select)
X_after_null = NullTransformer().fit_transform(X_after_z_score)
X_after_union = pd.concat([X[TIME_COL], X_after_null], axis=1)
model_hand = DummyEstimator(strategy="mean")
model_hand.fit(X_after_union)
output_by_hand = model_hand.predict(X_after_union)
assert output_estimator_null.equals(output_by_hand)
assert output_dummy.equals(output_by_hand)
def test_fit_predict():
"""Tests training mean estimator"""
model = DummyEstimator()
X = pd.DataFrame({
TIME_COL:
pd.date_range("2018-01-01", periods=3, freq="1D"),
VALUE_COL: [2, 3, 4]
})
model.fit(X)
predicted = model.predict(X)
expected = pd.DataFrame({
TIME_COL: X[TIME_COL],
PREDICTED_COL: np.repeat(3.0, X.shape[0])
})
assert predicted.equals(expected)
# with np.nan value
model = DummyEstimator()
X = pd.DataFrame({
TIME_COL:
pd.date_range("2018-01-01", periods=4, freq="1D"),
VALUE_COL: [2, 3, np.nan, 4]
})
model.fit(X)
predicted = model.predict(X)
expected = pd.DataFrame({
TIME_COL: X[TIME_COL],
PREDICTED_COL: np.repeat(3.0, X.shape[0])
})
assert predicted.equals(expected)
class BaseForecastEstimator(BaseEstimator, RegressorMixin, ABC):
"""A base class for forecast models. Fits a timeseries and predicts future values
Parameters
----------
score_func : callable, optional, default=mean_squared_error
Function to calculate model R2_null_model_score score,
with signature (actual, predicted).
`actual`, `predicted` are array-like with the same shape.
Smaller values are better.
coverage : float, optional, default=0.95
intended coverage of the prediction bands (0.0 to 1.0)
If None, the upper/lower predictions are not returned by `predict`
Every subclass must use `coverage` to set prediction band width. This ensures a common
BaseForecastEstimator interface for parameters used during fitting and forecast evaluation
null_model_params : dict with arguments passed to DummyRegressor, optional, default=None
Dictionary keys must be in ("strategy", "constant", "quantile")
Defines null model. model score is R2_null_model_score of model error relative to null model, evaluated by score_func
If None, model score is score_func of the model itself
Attributes
----------
null_model : DummyEstimator
null model used to measure model score
time_col_ : str
Name of input data time column
value_col_ : str
Name of input data value column
last_predicted_X_ : `pandas.DataFrame` or None
The ``X`` last passed to ``self.predict()``.
Used to speed up predictions if the same ``X`` is passed repeatedly.
Resets to None when ``self.fit()`` is called.
cached_predictions_ : `pandas.DataFrame` or None
The return value of the last call to ``self.predict()``.
Used to speed up predictions if the same ``X`` is passed repeatedly.
Resets to None when ``self.fit()`` is called.
"""
@abstractmethod
def __init__(self,
score_func=mean_squared_error,
coverage=0.95,
null_model_params=None):
"""Initializes attributes common to every BaseForecastEstimator
Subclasses must also have these parameters. Every subclass must call:
super().__init__(score_func=score_func, coverage=coverage, null_model_params=null_model_params)
"""
self.score_func = score_func
self.coverage = coverage
self.null_model_params = null_model_params
# initializes attributes defined in fit
self.null_model = None
self.time_col_ = None
self.value_col_ = None
# initializes attributes defined in predict
self.last_predicted_X_ = None # the most recent X passed to self.predict()
self.cached_predictions_ = None # the most recent return value of self.predict()
@abstractmethod
def fit(self,
X,
y=None,
time_col=cst.TIME_COL,
value_col=cst.VALUE_COL,
**fit_params):
"""Fits a model to training data
Also fits the null model, if specified, for use in evaluating the `score` function
Every subclass must call this::
super().fit(X, y=y, time_col=time_col, value_col=value_col, **fit_params)
Parameters
----------
X : `pandas.DataFrame`
Input timeseries, with timestamp column,
value column, and any additional regressors.
The value column is the response, included in
``X`` to allow transformation by `sklearn.pipeline`.
y : ignored
The original timeseries values, ignored.
(The y for fitting is included in X.)
time_col : `str`
Time column name in X.
value_col : `str`
Value column name in X.
fit_params : `dict`
Additional parameters supported by subclass `fit` or null model.
"""
self.time_col_ = time_col # to be used in `predict` to select proper column
self.value_col_ = value_col
# Null model must be initialized here, otherwise scikit-learn
# grid search will not be able to set the parameters.
# See https://scikit-learn.org/stable/developers/develop.html#instantiation.
if self.null_model_params is not None:
# Adds score function to null model parameters, and initializes null model
self.null_model_params["score_func"] = self.score_func
self.null_model = DummyEstimator(**self.null_model_params)
# Passes `sample_weight` rather than `**fit_params` to avoid unexpected keyword argument from the main
# estimator's parameters
sample_weight = fit_params.get("sample_weight")
self.null_model.fit(X,
y=y,
time_col=time_col,
value_col=value_col,
sample_weight=sample_weight)
# Clears the cached result, because it is no longer valid for the updated model
self.last_predicted_X_ = None
self.cached_predictions_ = None
@abstractmethod
def predict(self, X, y=None):
"""Creates forecast for dates specified in X
To enable caching, every subclass must call this at the beginning
of its ``.predict()``. Before returning the result, the subclass
``.predict()`` must set ``self.cached_predictions_`` to the return value.
Parameters
----------
X : `pandas.DataFrame`
Input timeseries with timestamp column and any additional regressors.
Timestamps are the dates for prediction.
Value column, if provided in X, is ignored.
y : ignored
Returns
-------
predictions : `pandas.DataFrame`
Forecasted values for the dates in X. Columns:
- TIME_COL dates
- PREDICTED_COL predictions
- PREDICTED_LOWER_COL lower bound of predictions, optional
- PREDICTED_UPPER_COL upper bound of predictions, optional
- [other columns], optional
``PREDICTED_LOWER_COL`` and ``PREDICTED_UPPER_COL`` are present
if ``self.coverage`` is not None.
"""
if self.cached_predictions_ is not None and X.equals(
self.last_predicted_X_):
log_message("Returning cached predictions.",
LoggingLevelEnum.DEBUG)
return self.cached_predictions_
else:
# Updates `last_predicted_X` to the new value.
# To enable caching, the subclass must set
# `self.cached_predictions` to the returned result.
self.last_predicted_X_ = X
return None
def summary(self):
"""Creates human readable string of how the model works, including relevant diagnostics
These details cannot be extracted from the forecast alone
Prints model configuration. Extend this in child class to print the trained model parameters.
Log message is printed to the cst.LOGGER_NAME logger.
"""
log_message(self,
LoggingLevelEnum.DEBUG) # print model input parameters
def score(self, X, y, sample_weight=None):
"""Default scorer for the estimator (Used in GridSearchCV/RandomizedSearchCV if scoring=None)
Notes
-----
If null_model_params is not None, returns R2_null_model_score of model error
relative to null model, evaluated by score_func.
If null_model_params is None, returns score_func of the model itself.
By default, grid search (with no `scoring` parameter) optimizes improvement of ``score_func``
against null model.
To optimize a different score function, pass `scoring` to GridSearchCV/RandomizedSearchCV.
Parameters
----------
X : `pandas.DataFrame`
Input timeseries with timestamp column and any additional regressors.
Value column, if provided in X, is ignored
y : `pandas.Series` or `numpy.array`
Actual value, used to compute error
sample_weight : `pandas.Series` or `numpy.array`
ignored
Returns
-------
score : `float` or None
Comparison of predictions against null predictions, according to specified score function
"""
y_pred = self.predict(X)[cst.PREDICTED_COL]
if self.null_model is not None:
y_pred_null = self.null_model.predict(X)[cst.PREDICTED_COL]
score = r2_null_model_score(y,
y_pred,
y_pred_null=y_pred_null,
loss_func=self.score_func)
else:
score = self.score_func(y, y_pred)
return score