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Source code for qiskit_optimization.problems.variable

# This code is part of Qiskit.
#
# (C) Copyright IBM 2019, 2021.
#
# 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.

"""Variable interface"""

from enum import Enum
from typing import Tuple, Union, Any

from .quadratic_program_element import QuadraticProgramElement
from ..exceptions import QiskitOptimizationError
from ..infinity import INFINITY


class VarType(Enum):
    """Constants defining variable type."""

    CONTINUOUS = 0
    BINARY = 1
    INTEGER = 2


[docs]class Variable(QuadraticProgramElement): """Representation of a variable.""" Type = VarType def __init__( self, quadratic_program: Any, name: str, lowerbound: Union[float, int] = 0, upperbound: Union[float, int] = INFINITY, vartype: VarType = VarType.CONTINUOUS, ) -> None: """Creates a new Variable. The variables is exposed by the top-level `QuadraticProgram` class in `QuadraticProgram.variables`. This constructor is not meant to be used externally. Args: quadratic_program: The parent QuadraticProgram. name: The variable name. lowerbound: The variable lowerbound. upperbound: The variable upperbound. vartype: The variable type. Raises: QiskitOptimizationError: if lowerbound is greater than upperbound. """ if lowerbound > upperbound: raise QiskitOptimizationError("Lowerbound is greater than upperbound!") super().__init__(quadratic_program) self._name = name self._lowerbound = lowerbound self._upperbound = upperbound self._vartype = vartype @property def name(self) -> str: """Returns the name of the variable. Returns: The name of the variable. """ return self._name @property def lowerbound(self) -> Union[float, int]: """Returns the lowerbound of the variable. Returns: The lower bound of the variable. """ return self._lowerbound @lowerbound.setter def lowerbound(self, lowerbound: Union[float, int]) -> None: """Sets the lowerbound of the variable. Args: lowerbound: The lower bound of the variable. Raises: QiskitOptimizationError: if lowerbound is greater than upperbound. """ if lowerbound > self.upperbound: raise QiskitOptimizationError("Lowerbound is greater than upperbound!") self._lowerbound = lowerbound @property def upperbound(self) -> Union[float, int]: """Returns the upperbound of the variable. Returns: The upperbound of the variable. """ return self._upperbound @upperbound.setter def upperbound(self, upperbound: Union[float, int]) -> None: """Sets the upperbound of the variable. Args: upperbound: The upperbound of the variable. Raises: QiskitOptimizationError: if upperbound is smaller than lowerbound. """ if self.lowerbound > upperbound: raise QiskitOptimizationError("Lowerbound is greater than upperbound!") self._upperbound = upperbound @property def vartype(self) -> VarType: """Returns the type of the variable. Returns: The variable type. """ return self._vartype @vartype.setter def vartype(self, vartype: VarType) -> None: """Sets the type of the variable. Args: vartype: The variable type. """ self._vartype = vartype
[docs] def as_tuple(self) -> Tuple[str, Union[float, int], Union[float, int], VarType]: """Returns a tuple corresponding to this variable. Returns: A tuple corresponding to this variable consisting of name, lowerbound, upperbound and variable type. """ return self.name, self.lowerbound, self.upperbound, self.vartype

© Copyright 2018, 2021, Qiskit Optimization Development Team.

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