def _ses_forecast(smoothing_level_constant: float, forecast_demand: Forecast,
forecast_length: int, orders_length: int) -> dict:
""" Private function for executing the simple exponential smoothing forecast.
"""
forecast_breakdown = [
i for i in forecast_demand.simple_exponential_smoothing(
smoothing_level_constant)
]
ape = LinearRegression(forecast_breakdown)
mape = forecast_demand.mean_aboslute_percentage_error_opt(
forecast_breakdown)
stats = ape.least_squared_error()
simple_forecast = forecast_demand.simple_exponential_smoothing_forecast(
forecast=forecast_breakdown, forecast_length=forecast_length)
sum_squared_error = forecast_demand.sum_squared_errors(
simple_forecast, smoothing_level_constant)
standard_error = forecast_demand.standard_error(sum_squared_error,
orders_length,
smoothing_level_constant)
regression_line = _regr_ln(stats=stats)
log.log(
logging.WARNING,
"A STANDARD simple exponential smoothing forecast has been completed.")
return {
'forecast_breakdown': forecast_breakdown,
'mape': mape,
'statistics': stats,
'forecast': simple_forecast,
'alpha': smoothing_level_constant,
'standard_error': standard_error,
'regression': [i for i in regression_line.get('regression')]
}
def simple_exponential_smoothing_evo(
self,
smoothing_level_constant: float,
initial_estimate_period: int,
recombination_type: str = 'single_point',
population_size: int = 10,
forecast_length: int = 5) -> dict:
""" Simple exponential smoothing using evolutionary algorithm for optimising smoothing level constant (alpha value)
Args:
initial_estimate_period (int): The number of previous data points required for initial level estimate.
smoothing_level_constant (float): Best guess at smoothing level constant appropriate for forecast.
Returns:
dict:
Example:
"""
log.log(
logging.INFO, "Executing simple exponential smoothing. "
"SMOOTHING_LEVEL: {} "
"INITIAL_ESTIMATE_PERIOD: {} "
"RECOMBINATION_TYPE: {} "
"POPULATION_SIZE: {} "
"FORECAST_LENGTH: {}".format(smoothing_level_constant,
initial_estimate_period,
recombination_type, population_size,
forecast_length))
if None != self.__recombination_type:
recombination_type = self.__recombination_type
sum_orders = 0
for demand in self.__orders[:initial_estimate_period]:
sum_orders += demand
avg_orders = sum_orders / initial_estimate_period
forecast_demand = Forecast(self.__orders, avg_orders)
#calls simple_exponential_smoothing method from Forecast object
ses_forecast = [
i for i in forecast_demand.simple_exponential_smoothing(
*(smoothing_level_constant, ))
]
sum_squared_error = forecast_demand.sum_squared_errors(
ses_forecast, smoothing_level_constant)
standard_error = forecast_demand.standard_error(
sum_squared_error, len(self.__orders), smoothing_level_constant)
evo_mod = OptimiseSmoothingLevelGeneticAlgorithm(
orders=self.__orders,
average_order=avg_orders,
smoothing_level=smoothing_level_constant,
population_size=population_size,
standard_error=standard_error,
recombination_type=recombination_type)
optimal_alpha = evo_mod.initial_population()
optimal_ses_forecast = [
i for i in forecast_demand.simple_exponential_smoothing(
optimal_alpha[1])
]
ape = LinearRegression(optimal_ses_forecast)
mape = forecast_demand.mean_aboslute_percentage_error_opt(
optimal_ses_forecast)
stats = ape.least_squared_error()
simple_forecast = forecast_demand.simple_exponential_smoothing_forecast(
forecast=optimal_ses_forecast, forecast_length=forecast_length)
sum_squared_error = forecast_demand.sum_squared_errors(
optimal_ses_forecast, optimal_alpha[1])
standard_error = forecast_demand.standard_error(
sum_squared_error, len(self.__orders), optimal_alpha[1])
regression = {
'regression': [(stats.get('slope') * i) + stats.get('intercept')
for i in range(0, 12)]
}
log.log(
logging.INFO,
"An OPTIMISED simple exponential smoothing forecast has been completed"
)
return {
'forecast_breakdown': optimal_ses_forecast,
'mape': mape,
'statistics': stats,
'forecast': simple_forecast,
'optimal_alpha': optimal_alpha[1],
'standard_error': standard_error,
'regression': [i for i in regression.get('regression')]
}
def holts_trend_corrected_exponential_smoothing_forecast(demand: list, alpha: float, gamma: float,
forecast_length: int = 4, initial_period: int = 6, **kwargs):
if len(kwargs) != 0:
if kwargs['optimise']:
total_orders = 0
for order in demand[:initial_period]:
total_orders += order
avg_orders = total_orders / initial_period
forecast_demand = Forecast(demand)
processed_demand = [{'t': index, 'demand': order} for index, order in enumerate(demand, 1)]
stats = LinearRegression(processed_demand)
log_stats = stats.least_squared_error(slice_end=6)
htces_forecast = [i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(alpha=alpha, gamma=gamma,
intercept=log_stats.get(
'intercept'),
slope=log_stats.get(
'slope'))]
sum_squared_error = forecast_demand.sum_squared_errors_indi_htces(squared_error=[htces_forecast],
alpha=alpha, gamma=gamma)
standard_error = forecast_demand.standard_error(sum_squared_error, len(demand), (alpha, gamma), 2)
evo_mod = OptimiseSmoothingLevelGeneticAlgorithm(orders=demand,
average_order=avg_orders,
population_size=10,
standard_error=standard_error,
recombination_type='single_point')
optimal_alpha = evo_mod.initial_population(individual_type='htces')
log.log(logging.WARNING,
'An optimal alpha {} and optimal gamma {} have been found.'.format(optimal_alpha[1][0],
optimal_alpha[1][1]))
htces_forecast = [i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(alpha=optimal_alpha[1][0],
gamma=optimal_alpha[1][1],
intercept=log_stats.get(
'intercept'),
slope=log_stats.get('slope'))]
holts_forecast = forecast_demand.holts_trend_corrected_forecast(forecast=htces_forecast,
forecast_length=forecast_length)
log.log(logging.INFO, 'An OPTIMAL Holts trend exponential smoothing forecast has been generated.')
sum_squared_error_opt = forecast_demand.sum_squared_errors_indi_htces(squared_error=[htces_forecast],
alpha=optimal_alpha[1][0],
gamma=optimal_alpha[1][1])
standard_error_opt = forecast_demand.standard_error(sum_squared_error_opt, len(demand),
(optimal_alpha[1][0], optimal_alpha[1][1]), 2)
ape = LinearRegression(htces_forecast)
mape = forecast_demand.mean_aboslute_percentage_error_opt(htces_forecast)
stats = ape.least_squared_error()
regression_line = deepcopy(regr_ln(stats=stats))
return {'forecast_breakdown': htces_forecast, 'forecast': holts_forecast, 'mape': mape, 'statistics': stats,
'optimal_alpha': optimal_alpha[1][0],
'optimal_gamma': optimal_alpha[1][1],
'SSE': sum_squared_error_opt,
'standard_error': standard_error_opt,
'original_standard_error': standard_error,
'regression': [i for i in regression_line.get('regression')]}
else:
forecast_demand = Forecast(demand)
processed_demand = [{'t': index, 'demand': order} for index, order in enumerate(demand, 1)]
stats = LinearRegression(processed_demand)
log_stats = stats.least_squared_error(slice_end=6)
htces_forecast = [i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(alpha=alpha, gamma=gamma,
intercept=log_stats.get(
'intercept'),
slope=log_stats.get(
'slope'))]
holts_forecast = forecast_demand.holts_trend_corrected_forecast(forecast=htces_forecast,
forecast_length=forecast_length)
log.log(logging.INFO, 'A STANDARD Holts trend exponential smoothing forecast has been generated.')
sum_squared_error = forecast_demand.sum_squared_errors_indi_htces(squared_error=[htces_forecast],
alpha=alpha, gamma=gamma)
ape = LinearRegression(htces_forecast)
mape = forecast_demand.mean_aboslute_percentage_error_opt(htces_forecast)
stats = ape.least_squared_error()
regression_line = regr_ln(stats=stats)
log.log(logging.WARNING, "A STANDARD Holts trend exponential smoothing forecast has been completed.")
return {'forecast_breakdown': htces_forecast,
'forecast': holts_forecast,
'mape': mape,
'statistics': stats,
'sum_squared_errors': sum_squared_error,
'regression': [i for i in regression_line.get('regression')]}
def holts_trend_corrected_exponential_smoothing_forecast(
demand: list,
alpha: float,
gamma: float,
forecast_length: int = 4,
initial_period: int = 6,
optimise: bool = True) -> dict:
""" Performs a holt's trend corrected exponential smoothing forecast on known demand
Args:
demand (list): Original historical demand.
alpha (float): smoothing constant
gamma (float):
forecast_length (int):
initial_period (int):
optimise (bool): Flag for using solver. Default is set to True.
Returns:
dict: Simple exponential forecast.
"""
if optimise:
total_orders = 0
for order in demand[:initial_period]:
total_orders += order
avg_orders = total_orders // initial_period
forecast_demand = Forecast(demand)
processed_demand = [{
't': index,
'demand': order
} for index, order in enumerate(demand, 1)]
stats = LinearRegression(processed_demand)
log_stats = stats.least_squared_error(slice_end=6)
htces_forecast = [
i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(
alpha=alpha,
gamma=gamma,
intercept=log_stats.get('intercept'),
slope=log_stats.get('slope'))
]
sum_squared_error = forecast_demand.sum_squared_errors_indi_htces(
squared_error=[htces_forecast], alpha=alpha, gamma=gamma)
standard_error = forecast_demand.standard_error(
sum_squared_error, len(demand), (alpha, gamma), 2)
evo_mod = OptimiseSmoothingLevelGeneticAlgorithm(
orders=demand,
average_order=avg_orders,
population_size=10,
standard_error=standard_error,
recombination_type='single_point')
optimal_alpha = evo_mod.initial_population(individual_type='htces')
log.log(
logging.WARNING,
'An optimal alpha {} and optimal gamma {} have been found.'.format(
optimal_alpha[1][0], optimal_alpha[1][1]))
htces_forecast = [
i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(
alpha=optimal_alpha[1][0],
gamma=optimal_alpha[1][1],
intercept=log_stats.get('intercept'),
slope=log_stats.get('slope'))
]
holts_forecast = forecast_demand.holts_trend_corrected_forecast(
forecast=htces_forecast, forecast_length=forecast_length)
log.log(
logging.INFO,
'An OPTIMAL Holts trend exponential smoothing forecast has been generated.'
)
sum_squared_error_opt = forecast_demand.sum_squared_errors_indi_htces(
squared_error=[htces_forecast],
alpha=optimal_alpha[1][0],
gamma=optimal_alpha[1][1])
standard_error_opt = forecast_demand.standard_error(
sum_squared_error_opt, len(demand),
(optimal_alpha[1][0], optimal_alpha[1][1]), 2)
ape = LinearRegression(htces_forecast)
mape = forecast_demand.mean_aboslute_percentage_error_opt(
htces_forecast)
stats = ape.least_squared_error()
regression_line = deepcopy(_regr_ln(stats=stats))
return {
'forecast_breakdown': htces_forecast,
'forecast': holts_forecast,
'mape': mape,
'statistics': stats,
'optimal_alpha': optimal_alpha[1][0],
'optimal_gamma': optimal_alpha[1][1],
'SSE': sum_squared_error_opt,
'standard_error': standard_error_opt,
'original_standard_error': standard_error,
'regression': [i for i in regression_line.get('regression')]
}
else:
forecast_demand = Forecast(demand)
processed_demand = [{
't': index,
'demand': order
} for index, order in enumerate(demand, 1)]
stats = LinearRegression(processed_demand)
log_stats = stats.least_squared_error(slice_end=6)
htces_forecast = [
i for i in
forecast_demand.holts_trend_corrected_exponential_smoothing(
alpha=alpha,
gamma=gamma,
intercept=log_stats.get('intercept'),
slope=log_stats.get('slope'))
]
holts_forecast = forecast_demand.holts_trend_corrected_forecast(
forecast=htces_forecast, forecast_length=forecast_length)
log.log(
logging.INFO,
'A STANDARD Holts trend exponential smoothing forecast has been generated.'
)
sum_squared_error = forecast_demand.sum_squared_errors_indi_htces(
squared_error=[htces_forecast], alpha=alpha, gamma=gamma)
ape = LinearRegression(htces_forecast)
mape = forecast_demand.mean_aboslute_percentage_error_opt(
htces_forecast)
stats = ape.least_squared_error()
regression_line = _regr_ln(stats=stats)
log.log(
logging.WARNING,
"A STANDARD Holts trend exponential smoothing forecast has been completed."
)
return {
'forecast_breakdown': htces_forecast,
'forecast': holts_forecast,
'mape': mape,
'statistics': stats,
'sum_squared_errors': sum_squared_error,
'regression': [i for i in regression_line.get('regression')]
}
