"""Desdeo-problem variable related definitions.
This file includes definition of Variable class (with initial and current
values and value bounds), variable_builder, and error classes for Variable
and VariableBuilder.
"""
from os import path
from typing import List, Tuple, Union
import numpy as np
[docs]class VariableError(Exception):
"""Raised when an error is encountered during the handling of the
Variable objects.
"""
pass
[docs]class VariableBuilderError(Exception):
"""Raised when an error is encountered during the handling of the
Variable objects.
"""
pass
[docs]class Variable:
"""Simple variable with a name, initial value and bounds.
Arguments:
name (str): Name of the variable
initial_value (float): The initial value of the variable.
lower_bound (float, optional): Lower bound of the variable. Defaults
to negative infinity.
upper_bound (float, optional): Upper bound of the variable. Defaults
to positive infinity.
Attributes:
name (str): Name of the variable.
initial_value (float): Initial value of the variable.
lower_bound (float): Lower bound of the variable.
upper_bound (float): Upper bound of the variable.
current_value (float): The current value the variable holds.
Raises:
VariableError: Bounds are incorrect.
"""
def __init__(
self,
name: str,
initial_value: float,
lower_bound: float = -np.inf,
upper_bound: float = np.inf,
) -> None:
self.__name: str = name
self.__initial_value: float
self.__lower_bound: float
self.__upper_bound: float
self.__current_value: float # NOTE: This is probably a useless attr
# Check that the bounds make sense
if not (lower_bound < upper_bound):
msg = ("Lower bound {} should be less than the upper bound " "{}.").format(lower_bound, upper_bound)
raise VariableError(msg)
# Check that the initial value is between the bounds
if not (lower_bound <= initial_value <= upper_bound):
msg = "The initial value {} should be between the " "upper ({}) and lower ({}) bounds.".format(
initial_value, lower_bound, upper_bound
)
raise VariableError(msg)
self.__lower_bound = lower_bound
self.__upper_bound = upper_bound
self.__initial_value = initial_value
self.__current_value = initial_value
@property
def name(self) -> str:
"""Property: name
Returns:
str: The name of the variable.
"""
return self.__name
@property
def initial_value(self) -> float:
"""Property: initial_value
Returns:
float: The initial value of the variable.
"""
return self.__initial_value
@property
def current_value(self) -> float:
"""Property: current_value
Returns:
float: The current value of the variable
"""
return self.__current_value
@current_value.setter
def current_value(self, value: float):
"""Setter: current_value
Args:
float: The updated value for the current_value variable.
"""
self.__current_value = value
[docs] def get_bounds(self) -> Tuple[float, float]:
"""Return the bounds of the variables as a tuple.
Returns:
tuple(float, float): A tuple consisting of (lower_bound,
upper_bound)
"""
return (self.__lower_bound, self.__upper_bound)
[docs]def variable_builder(
names: List[str],
initial_values: Union[List[float], np.ndarray],
lower_bounds: Union[List[float], np.ndarray] = None,
upper_bounds: Union[List[float], np.ndarray] = None,
) -> List[Variable]:
"""Automatically build all variable objects.
Arguments:
names (List[str]): Names of the variables
initial_values (np.ndarray): Initial values taken by the variables.
lower_bounds (Union[List[float], np.ndarray], optional): Lower bounds of the
variables. If None, it defaults to negative infinity. Defaults to None.
upper_bounds (Union[List[float], np.ndarray], optional): Upper bounds of the
variables. If None, it defaults to positive infinity. Defaults to None.
Raises:
VariableError: Lengths of the input arrays are different.
Returns:
List[Variable]: List of variable objects
"""
# assert that all inputs have the same size
num_of_variables = len(names)
if initial_values is None:
initial_values = [None] * num_of_variables
if not (num_of_variables == len(initial_values)):
msg = (
"The length of the list of names and the number of elements in the "
"initial_values array should be the same"
)
raise VariableBuilderError(msg)
if lower_bounds is None:
lower_bounds = [-np.inf] * num_of_variables
if not (num_of_variables == len(lower_bounds)):
msg = (
"The length of the list of names and the number of elements in the " "lower_bounds array should be the same"
)
raise VariableBuilderError(msg)
if upper_bounds is None:
upper_bounds = [np.inf] * num_of_variables
if not (num_of_variables == len(upper_bounds)):
msg = (
"The length of the list of names and the number of elements in the " "upper_bounds array should be the same"
)
raise VariableBuilderError(msg)
# if most checks passed
variables = [Variable(*var_data) for var_data in zip(names, initial_values, lower_bounds, upper_bounds)]
return variables
