Pending deprecate algo eigen_solvers

qiskit/algorithms/eigen_solvers/eigen_solver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2020.
+# (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
@@ -18,18 +18,34 @@
 import numpy as np
 
 from qiskit.opflow import OperatorBase
+from qiskit.utils.deprecation import deprecate_function
 from ..algorithm_result import AlgorithmResult
 from ..list_or_dict import ListOrDict
 
 
 class Eigensolver(ABC):
-    """The Eigensolver Interface.
+    """Pending deprecation: Eigensolver Interface.
+
+    The Eigensolver interface has been superseded by the
+    :class:`qiskit.algorithms.eigensolvers.Eigensolver` interface.
+    This interface will be deprecated in a future release and subsequently
+    removed after that.
 
     Algorithms that can compute eigenvalues for an operator
     may implement this interface to allow different algorithms to be
     used interchangeably.
     """
 
+    @deprecate_function(
+        "The Eigensolver interface has been superseded by the "
+        "qiskit.algorithms.eigensolvers.Eigensolver interface. "
+        "This interface will be deprecated in a future release and subsequently "
+        "removed after that.",
+        category=PendingDeprecationWarning,
+    )
+    def __init__(self) -> None:
+        pass
+
     @abstractmethod
     def compute_eigenvalues(
         self, operator: OperatorBase, aux_operators: Optional[ListOrDict[OperatorBase]] = None
@@ -63,8 +79,22 @@ def supports_aux_operators(cls) -> bool:
 
 
 class EigensolverResult(AlgorithmResult):
-    """Eigensolver Result."""
+    """Pending deprecation: Eigensolver Result.
+
+    The EigensolverResult class has been superseded by the
+    :class:`qiskit.algorithms.eigensolvers.EigensolverResult` class.
+    This class will be deprecated in a future release and subsequently
+    removed after that.
+
+    """
 
+    @deprecate_function(
+        "The EigensolverResult class has been superseded by the "
+        "qiskit.algorithms.eigensolvers.EigensolverResult class. "
+        "This class will be deprecated in a future release and subsequently "
+        "removed after that.",
+        category=PendingDeprecationWarning,
+    )
     def __init__(self) -> None:
         super().__init__()
         self._eigenvalues = None

qiskit/algorithms/eigen_solvers/numpy_eigen_solver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2018, 2021.
+# (C) Copyright IBM 2018, 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
@@ -14,12 +14,13 @@
 
 import logging
 from typing import Callable, List, Optional, Tuple, Union
-
+import warnings
 import numpy as np
 from scipy import sparse as scisparse
 
 from qiskit.opflow import I, ListOp, OperatorBase, StateFn
 from qiskit.utils.validation import validate_min
+from qiskit.utils.deprecation import deprecate_function
 from ..exceptions import AlgorithmError
 from .eigen_solver import Eigensolver, EigensolverResult
 from ..list_or_dict import ListOrDict
@@ -32,7 +33,12 @@
 
 class NumPyEigensolver(Eigensolver):
     r"""
-    The NumPy Eigensolver algorithm.
+    Pending deprecation: NumPy Eigensolver algorithm.
+
+    The NumPyEigensolver class has been superseded by the
+    :class:`qiskit.algorithms.eigensolvers.NumPyEigensolver` class.
+    This class will be deprecated in a future release and subsequently
+    removed after that.
 
     NumPy Eigensolver computes up to the first :math:`k` eigenvalues of a complex-valued square
     matrix of dimension :math:`n \times n`, with :math:`k \leq n`.
@@ -43,6 +49,13 @@ class NumPyEigensolver(Eigensolver):
         operator size, mostly in terms of number of qubits it represents, gets larger.
     """
 
+    @deprecate_function(
+        "The NumPyEigensolver class has been superseded by the "
+        "qiskit.algorithms.eigensolvers.NumPyEigensolver class. "
+        "This class will be deprecated in a future release and subsequently "
+        "removed after that.",
+        category=PendingDeprecationWarning,
+    )
     def __init__(
         self,
         k: int = 1,
@@ -61,7 +74,9 @@ def __init__(
                 fewer elements and can even be empty.
         """
         validate_min("k", k, 1)
-        super().__init__()
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            super().__init__()
 
         self._in_k = k
         self._k = k

qiskit/algorithms/eigen_solvers/vqd.py

@@ -17,6 +17,7 @@
 
 from typing import Optional, List, Callable, Union, Dict, Tuple
 import logging
+import warnings
 from time import time
 import numpy as np
 
@@ -37,6 +38,7 @@
 from qiskit.opflow.gradients import GradientBase
 from qiskit.utils.validation import validate_min
 from qiskit.utils.backend_utils import is_aer_provider
+from qiskit.utils.deprecation import deprecate_function
 from qiskit.utils import QuantumInstance
 from ..list_or_dict import ListOrDict
 from ..optimizers import Optimizer, SLSQP, Minimizer
@@ -50,7 +52,12 @@
 
 
 class VQD(VariationalAlgorithm, Eigensolver):
-    r"""The Variational Quantum Deflation algorithm.
+    r"""Pending deprecation: Variational Quantum Deflation algorithm.
+
+    The VQD class has been superseded by the
+    :class:`qiskit.algorithms.eigensolvers.VQD` class.
+    This class will be deprecated in a future release and subsequently
+    removed after that.
 
     `VQD <https://arxiv.org/abs/1805.08138>`__ is a quantum algorithm that uses a
     variational technique to find
@@ -89,6 +96,13 @@ class VQD(VariationalAlgorithm, Eigensolver):
 
     """
 
+    @deprecate_function(
+        "The VQD class has been superseded by the "
+        "qiskit.algorithms.eigensolvers.VQD class. "
+        "This class will be deprecated in a future release and subsequently "
+        "removed after that.",
+        category=PendingDeprecationWarning,
+    )
     def __init__(
         self,
         ansatz: Optional[QuantumCircuit] = None,
@@ -149,7 +163,9 @@ def __init__(
         """
         validate_min("max_evals_grouped", max_evals_grouped, 1)
 
-        super().__init__()
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            super().__init__()
 
         self._max_evals_grouped = max_evals_grouped
         self._circuit_sampler = None  # type: Optional[CircuitSampler]
@@ -741,8 +757,22 @@ def _get_eigenstate(self, optimal_parameters) -> Union[List[float], Dict[str, in
 
 
 class VQDResult(VariationalResult, EigensolverResult):
-    """VQD Result."""
+    """Pending deprecation: VQD Result.
+
+    The VQDResult class has been superseded by the
+    :class:`qiskit.algorithms.eigensolvers.VQDResult` class.
+    This class will be deprecated in a future release and subsequently
+    removed after that.
+
+    """
 
+    @deprecate_function(
+        "The VQDResult class has been superseded by the "
+        "qiskit.algorithms.eigensolvers.VQDResult class. "
+        "This class will be deprecated in a future release and subsequently "
+        "removed after that.",
+        category=PendingDeprecationWarning,
+    )
     def __init__(self) -> None:
         super().__init__()
         self._cost_function_evals = None

releasenotes/notes/pending-deprecate-eigen-solvers-2a4068cc9f83fba2.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    Module :mod:`qiskit.algorithms.eigen_solvers` is pending deprecation and
+    is superseded by :mod:`qiskit.algorithms.eigensolvers`