Source code for qiskit.algorithms.minimum_eigen_solvers.numpy_minimum_eigen_solver

# This code is part of Qiskit.
#
# (C) Copyright IBM 2020, 2022.
#
# 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.

"""The Numpy Minimum Eigensolver algorithm."""
from __future__ import annotations

import logging
import warnings
from collections.abc import Callable

import numpy as np

from qiskit.opflow import OperatorBase
from qiskit.utils.deprecation import deprecate_func
from ..eigen_solvers.numpy_eigen_solver import NumPyEigensolver
from .minimum_eigen_solver import MinimumEigensolver, MinimumEigensolverResult
from ..list_or_dict import ListOrDict

logger = logging.getLogger(__name__)


class NumPyMinimumEigensolver(MinimumEigensolver):
    """
    Deprecated: Numpy Minimum Eigensolver algorithm.

    The NumPyMinimumEigensolver class has been superseded by the
    :class:`qiskit.algorithms.minimum_eigensolvers.NumPyMinimumEigensolver` class.
    This class will be deprecated in a future release and subsequently
    removed after that.

    """

    @deprecate_func(
        additional_msg=(
            "Instead, use the class "
            "``qiskit.algorithms.minimum_eigensolvers.NumPyMinimumEigensolver``. "
            "See https://qisk.it/algo_migration for a migration guide."
        ),
        since="0.24.0",
        package_name="qiskit-terra",
    )
    def __init__(
        self,
        filter_criterion: Callable[
            [list | np.ndarray, float, ListOrDict[float] | None], bool
        ] = None,
    ) -> None:
        """
        Args:
            filter_criterion: callable that allows to filter eigenvalues/eigenstates. The minimum
                eigensolver is only searching over feasible states and returns an eigenstate that
                has the smallest eigenvalue among feasible states. The callable has the signature
                `filter(eigenstate, eigenvalue, aux_values)` and must return a boolean to indicate
                whether to consider this value or not. If there is no
                feasible element, the result can even be empty.
        """
        with warnings.catch_warnings():
            warnings.simplefilter("ignore")
            super().__init__()
        self._ces = NumPyEigensolver(filter_criterion=filter_criterion)
        self._ret = MinimumEigensolverResult()

    @property
    def filter_criterion(
        self,
    ) -> Callable[[list | np.ndarray, float, ListOrDict[float] | None], bool] | None:
        """returns the filter criterion if set"""
        return self._ces.filter_criterion

    @filter_criterion.setter
    def filter_criterion(
        self,
        filter_criterion: Callable[[list | np.ndarray, float, ListOrDict[float] | None], bool]
        | None,
    ) -> None:
        """set the filter criterion"""
        self._ces.filter_criterion = filter_criterion

    @classmethod
    def supports_aux_operators(cls) -> bool:
        return NumPyEigensolver.supports_aux_operators()

    def compute_minimum_eigenvalue(
        self, operator: OperatorBase, aux_operators: ListOrDict[OperatorBase] | None = None
    ) -> MinimumEigensolverResult:
        super().compute_minimum_eigenvalue(operator, aux_operators)
        result_ces = self._ces.compute_eigenvalues(operator, aux_operators)
        self._ret = MinimumEigensolverResult()
        if result_ces.eigenvalues is not None and len(result_ces.eigenvalues) > 0:
            self._ret.eigenvalue = result_ces.eigenvalues[0]
            self._ret.eigenstate = result_ces.eigenstates[0]
            if result_ces.aux_operator_eigenvalues:
                self._ret.aux_operator_eigenvalues = result_ces.aux_operator_eigenvalues[0]

        logger.debug("MinimumEigensolver:\n%s", self._ret)

        return self._ret