# This code is part of a Qiskit project.
#
# (C) Copyright IBM 2019, 2023.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""Abstract Constraint."""
from abc import abstractmethod
from enum import Enum
from typing import Union, List, Dict, Any
from numpy import ndarray
from .quadratic_program_element import QuadraticProgramElement
from ..exceptions import QiskitOptimizationError
class ConstraintSense(Enum):
"""Constraint Sense Type."""
# pylint: disable=invalid-name
LE = 0
GE = 1
EQ = 2
@staticmethod
def convert(sense: Union[str, "ConstraintSense"]) -> "ConstraintSense":
"""Convert a string into a corresponding sense of constraints
Args:
sense: A string or sense of constraints
Returns:
The sense of constraints
Raises:
QiskitOptimizationError: if the input string is invalid.
"""
if isinstance(sense, ConstraintSense):
return sense
sense = sense.upper()
if sense not in [
"E",
"L",
"G",
"EQ",
"LE",
"GE",
"=",
"==",
"<=",
"<",
">=",
">",
]:
raise QiskitOptimizationError(f"Invalid sense: {sense}")
if sense in ["E", "EQ", "=", "=="]:
return ConstraintSense.EQ
elif sense in ["L", "LE", "<=", "<"]:
return ConstraintSense.LE
else:
return ConstraintSense.GE
@property
def label(self) -> str:
"""Label of the constraint sense
Returns:
The label of the constraint sense ('<=', '>=', or '==')
"""
if self is ConstraintSense.LE:
return "<="
elif self is ConstraintSense.GE:
return ">="
else:
return "=="
[docs]class Constraint(QuadraticProgramElement):
"""Abstract Constraint Class."""
Sense = ConstraintSense
def __init__(
self, quadratic_program: Any, name: str, sense: ConstraintSense, rhs: float
) -> None:
"""Initializes the constraint.
Args:
quadratic_program: The parent QuadraticProgram.
name: The name of the constraint.
sense: The sense of the constraint.
rhs: The right-hand-side of the constraint.
"""
super().__init__(quadratic_program)
self._name = name
self._sense = sense
self._rhs = rhs
@property
def name(self) -> str:
"""Returns the name of the constraint.
Returns:
The name of the constraint.
"""
return self._name
@property
def sense(self) -> ConstraintSense:
"""Returns the sense of the constraint.
Returns:
The sense of the constraint.
"""
return self._sense
@sense.setter
def sense(self, sense: ConstraintSense) -> None:
"""Sets the sense of the constraint.
Args:
sense: The sense of the constraint.
"""
self._sense = sense
@property
def rhs(self) -> float:
"""Returns the right-hand-side of the constraint.
Returns:
The right-hand-side of the constraint.
"""
return self._rhs
@rhs.setter
def rhs(self, rhs: float) -> None:
"""Sets the right-hand-side of the constraint.
Args:
rhs: The right-hand-side of the constraint.
"""
self._rhs = rhs
[docs] @abstractmethod
def evaluate(self, x: Union[ndarray, List, Dict[Union[int, str], float]]) -> float:
"""Evaluate left-hand-side of constraint for given values of variables.
Args:
x: The values to be used for the variables.
Returns:
The left-hand-side of the constraint.
"""
raise NotImplementedError()