# This code is part of a Qiskit project.
#
# (C) Copyright IBM 2019, 2025.
#
# 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.
"""Linear Constraint."""
from __future__ import annotations
from typing import Any
from numpy import ndarray
from scipy.sparse import spmatrix
from .constraint import Constraint, ConstraintSense
from .linear_expression import LinearExpression
[docs]
class LinearConstraint(Constraint):
"""Representation of a linear constraint."""
# Note: added, duplicating in effect that in Constraint, to avoid issues with Sphinx
Sense = ConstraintSense
def __init__( # pylint: disable=too-many-positional-arguments
self,
quadratic_program: Any,
name: str,
linear: ndarray | spmatrix | list[float] | dict[str | int, float],
sense: ConstraintSense,
rhs: float,
) -> None:
"""
Args:
quadratic_program: The parent quadratic program.
name: The name of the constraint.
linear: The coefficients specifying the linear 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)
@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: ndarray | spmatrix | list[float] | dict[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)
[docs]
def evaluate(self, x: ndarray | list | dict[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)
def __repr__(self):
# pylint: disable=cyclic-import
from ..translators.prettyprint import expr2str, DEFAULT_TRUNCATE
lhs = expr2str(linear=self.linear, 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)
return f"{lhs} {self.sense.label} {self.rhs} '{self.name}'"