Source code for qiskit_optimization.applications.number_partition

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"""An application class for the number partitioning."""

from typing import List, Union

import numpy as np
from import Model

from qiskit_optimization.algorithms import OptimizationResult
from qiskit_optimization.problems.quadratic_program import QuadraticProgram
from qiskit_optimization.translators import from_docplex_mp
from .optimization_application import OptimizationApplication

[docs]class NumberPartition(OptimizationApplication): """Optimization application for the "number partition" [1] problem. References: [1]: "Partition problem", """ def __init__(self, number_set: List[int]) -> None: """ Args: number_set: A list of integers """ self._number_set = number_set
[docs] def to_quadratic_program(self) -> QuadraticProgram: """Convert a number partitioning problem instance into a :class:`~qiskit_optimization.problems.QuadraticProgram` Returns: The :class:`~qiskit_optimization.problems.QuadraticProgram` created from the number partitioning problem instance. """ mdl = Model(name="Number partitioning") x = {i: mdl.binary_var(name=f"x_{i}") for i in range(len(self._number_set))} mdl.add_constraint( mdl.sum(num * (-2 * x[i] + 1) for i, num in enumerate(self._number_set)) == 0 ) op = from_docplex_mp(mdl) return op
[docs] def interpret(self, result: Union[OptimizationResult, np.ndarray]) -> List[List[int]]: """Interpret a result as a list of subsets Args: result: The calculated result of the problem Returns: A list of subsets whose sum is the half of the total. """ x = self._result_to_x(result) num_subsets = [[], []] # type: List[List[int]] for i, value in enumerate(x): if value == 0: num_subsets[0].append(self._number_set[i]) else: num_subsets[1].append(self._number_set[i]) return num_subsets