# 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.
"""Quadratic Constraint."""
from typing import Union, List, Dict, Tuple, Any
from numpy import ndarray
from scipy.sparse import spmatrix
from .constraint import Constraint, ConstraintSense
from .linear_expression import LinearExpression
from .quadratic_expression import QuadraticExpression
[docs]class QuadraticConstraint(Constraint):
"""Representation of a quadratic constraint."""
# Note: added, duplicating in effect that in Constraint, to avoid issues with Sphinx
Sense = ConstraintSense
def __init__(
self,
quadratic_program: Any,
name: str,
linear: Union[ndarray, spmatrix, List[float], Dict[Union[str, int], float]],
quadratic: Union[
ndarray,
spmatrix,
List[List[float]],
Dict[Tuple[Union[int, str], Union[int, str]], float],
],
sense: ConstraintSense,
rhs: float,
) -> None:
"""Constructs a quadratic constraint, consisting of a linear and a quadratic term.
Args:
quadratic_program: The parent quadratic program.
name: The name of the constraint.
linear: The coefficients specifying the linear part of the constraint.
quadratic: The coefficients specifying the linear part of the constraint.
sense: The sense of the constraint.
rhs: The right-hand-side of the constraint.
"""
super().__init__(quadratic_program, name, sense, rhs)
self._linear = LinearExpression(quadratic_program, linear)
self._quadratic = QuadraticExpression(quadratic_program, quadratic)
@property
def linear(self) -> LinearExpression:
"""Returns the linear expression corresponding to the left-hand-side of the constraint.
Returns:
The left-hand-side linear expression.
"""
return self._linear
@linear.setter
def linear(
self,
linear: Union[ndarray, spmatrix, List[float], Dict[Union[str, int], float]],
) -> None:
"""Sets the linear expression corresponding to the left-hand-side of the constraint.
The coefficients can either be given by an array, a (sparse) 1d matrix, a list or a
dictionary.
Args:
linear: The linear coefficients of the left-hand-side.
"""
self._linear = LinearExpression(self.quadratic_program, linear)
@property
def quadratic(self) -> QuadraticExpression:
"""Returns the quadratic expression corresponding to the left-hand-side of the constraint.
Returns:
The left-hand-side quadratic expression.
"""
return self._quadratic
@quadratic.setter
def quadratic(
self,
quadratic: Union[
ndarray,
spmatrix,
List[List[float]],
Dict[Tuple[Union[int, str], Union[int, str]], float],
],
) -> None:
"""Sets the quadratic expression corresponding to the left-hand-side of the constraint.
The coefficients can either be given by an array, a (sparse) matrix, a list or a
dictionary.
Args:
quadratic: The quadratic coefficients of the left-hand-side.
"""
self._quadratic = QuadraticExpression(self.quadratic_program, quadratic)
[docs] def evaluate(self, x: Union[ndarray, List, Dict[Union[int, str], float]]) -> float:
"""Evaluate the left-hand-side of the constraint.
Args:
x: The values of the variables to be evaluated.
Returns:
The left-hand-side of the constraint given the variable values.
"""
return self.linear.evaluate(x) + self.quadratic.evaluate(x)
def __repr__(self):
# pylint: disable=cyclic-import
from ..translators.prettyprint import expr2str, DEFAULT_TRUNCATE
lhs = expr2str(linear=self.linear, quadratic=self.quadratic, truncate=DEFAULT_TRUNCATE)
return f"<{self.__class__.__name__}: {lhs} {self.sense.label} {self.rhs} '{self.name}'>"
def __str__(self):
# pylint: disable=cyclic-import
from ..translators.prettyprint import expr2str
lhs = expr2str(linear=self.linear, quadratic=self.quadratic)
return f"{lhs} {self.sense.label} {self.rhs} '{self.name}'"