class ARIMAModel(ModelStrategy):
'''
A class for an Autoregressive Integrated Moving Average Model and the standard operations on it
'''
def __init__(self, hparams, log_dir=None):
univariate = True
model = None
name = 'ARIMA'
self.auto_params = hparams['AUTO_PARAMS']
self.p = int(hparams.get('P', 30))
self.d = int(hparams.get('D', 0))
self.q = int(hparams.get('Q', 0))
super(ARIMAModel, self).__init__(model,
univariate,
name,
log_dir=log_dir)
def fit(self, dataset):
'''
Fits an ARIMA forecasting model
:param dataset: A Pandas DataFrame with 2 columns: Date and Consumption
'''
if dataset.shape[1] != 2:
raise Exception(
'Univariate models cannot fit with datasets with more than 1 feature.'
)
dataset.rename(columns={
'Date': 'ds',
'Consumption': 'y'
},
inplace=True)
series = dataset.set_index('ds')
if self.auto_params:
best_model = pmdarima.auto_arima(series,
seasonal=False,
stationary=False,
information_criterion='aic',
max_order=2 * (self.p + self.q),
max_p=2 * self.p,
max_d=2 * self.d,
max_q=2 * self.q,
error_action='ignore')
order = best_model.order
print("Best ARIMA params: (p, d, q):", best_model.order)
else:
order = (self.p, self.d, self.q)
self.model = ARIMA(series, order=order).fit()
print(self.model.summary())
return
def evaluate(self, train_set, test_set, save_dir=None, plot=False):
'''
Evaluates performance of ARIMA model on test set
:param train_set: A Pandas DataFrame with 2 columns: Date and Consumption
:param test_set: A Pandas DataFrame with 2 columns: Date and Consumption
:param save_dir: Directory in which to save forecast metrics
:param plot: Flag indicating whether to plot the forecast evaluation
'''
train_set.rename(columns={
'Date': 'ds',
'Consumption': 'y'
},
inplace=True)
test_set.rename(columns={
'Date': 'ds',
'Consumption': 'y'
},
inplace=True)
train_set = train_set.set_index('ds')
test_set = test_set.set_index('ds')
train_set["model"] = self.model.fittedvalues
test_set["forecast"] = self.forecast(
test_set.shape[0])['Consumption'].tolist()
df_forecast = train_set.append(test_set).rename(columns={'y': 'gt'})
test_metrics = self.evaluate_forecast(df_forecast,
save_dir=save_dir,
plot=plot)
return test_metrics
def forecast(self, days, recent_data=None):
'''
Create a forecast for the test set. Note that this is different than obtaining predictions for the test set.
The model makes a prediction for the provided example, then uses the result for the next prediction.
Repeat this process for a specified number of days.
:param days: Number of days into the future to produce a forecast for
:param recent_data: A factual example for the first prediction
:return: An array of predictions
'''
forecast_df = self.model.forecast(steps=days).reset_index(level=0)
forecast_df.columns = ['Date', 'Consumption']
return forecast_df
def save(self, save_dir, scaler_dir=None):
'''
Saves the model to disk
:param save_dir: Directory in which to save the model
'''
if self.model:
model_path = os.path.join(save_dir,
self.name + self.train_date + '.pkl')
self.model.save(model_path) # Serialize and save the model object
def load(self, model_path, scaler_path=None):
'''
Loads the model from disk
:param model_path: Path to saved model
'''
if os.path.splitext(model_path)[1] != '.pkl':
raise Exception('Model file path for ' + self.name +
' must have ".pkl" extension.')
self.model = ARIMAResults.load(model_path)
return
def fit_model(self, train_data, namefile):
model = ARIMA(train_data, order=(2, 1, 3), enforce_stationarity=True)
model = model.fit()
model.summary()
model.save(namefile + '.pickle')
return model
