Fix mypy errors (algorithms) (Qiskit#8271)

* Fix mypy errors (algorithms)

* Fix formating

Co-authored-by: Julien Gacon <gaconju@gmail.com>

* Remove ignores, fix imports and a couple of small bugs

* More fixes

* Update qiskit/algorithms/minimum_eigen_solvers/vqe.py

Co-authored-by: Julien Gacon <gaconju@gmail.com>

* More fixes

* Remove TODO

* Fix `eval_observables` with `Backend` parameter

* Fix some more annotations

* Fix some TODOs

* Get rid of typing imports where possible

* Fix annotation

* Fix wrong result population

* Fix result types for VQD

* Fix lint

* Remove trailing mypy comment

---------

Co-authored-by: Julien Gacon <gaconju@gmail.com>

qiskit/algorithms/amplitude_amplifiers/amplification_problem.py

@@ -11,8 +11,10 @@
 # that they have been altered from the originals.
 
 """The Amplification problem class."""
+from __future__ import annotations
 
-from typing import Optional, Callable, Any, Union, List
+from collections.abc import Callable
+from typing import Any
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.circuit.library import GroverOperator
@@ -29,14 +31,12 @@ class AmplificationProblem:
 
     def __init__(
         self,
-        oracle: Union[QuantumCircuit, Statevector],
-        state_preparation: Optional[QuantumCircuit] = None,
-        grover_operator: Optional[QuantumCircuit] = None,
-        post_processing: Optional[Callable[[str], Any]] = None,
-        objective_qubits: Optional[Union[int, List[int]]] = None,
-        is_good_state: Optional[
-            Union[Callable[[str], bool], List[int], List[str], Statevector]
-        ] = None,
+        oracle: QuantumCircuit | Statevector,
+        state_preparation: QuantumCircuit | None = None,
+        grover_operator: QuantumCircuit | None = None,
+        post_processing: Callable[[str], Any] | None = None,
+        objective_qubits: int | list[int] | None = None,
+        is_good_state: Callable[[str], bool] | list[int] | list[str] | Statevector | None = None,
     ) -> None:
         r"""
         Args:
@@ -68,7 +68,7 @@ def __init__(
             self._is_good_state = None
 
     @property
-    def oracle(self) -> Union[QuantumCircuit, Statevector]:
+    def oracle(self) -> QuantumCircuit | Statevector:
         """Return the oracle.
 
         Returns:
@@ -77,7 +77,7 @@ def oracle(self) -> Union[QuantumCircuit, Statevector]:
         return self._oracle
 
     @oracle.setter
-    def oracle(self, oracle: Union[QuantumCircuit, Statevector]) -> None:
+    def oracle(self, oracle: QuantumCircuit | Statevector) -> None:
         """Set the oracle.
 
         Args:
@@ -100,7 +100,7 @@ def state_preparation(self) -> QuantumCircuit:
         return self._state_preparation
 
     @state_preparation.setter
-    def state_preparation(self, state_preparation: Optional[QuantumCircuit]) -> None:
+    def state_preparation(self, state_preparation: QuantumCircuit | None) -> None:
         r"""Set the :math:`\mathcal{A}` operator. If None, a layer of Hadamard gates is used.
 
         Args:
@@ -130,7 +130,7 @@ def post_processing(self, post_processing: Callable[[str], Any]) -> None:
         self._post_processing = post_processing
 
     @property
-    def objective_qubits(self) -> List[int]:
+    def objective_qubits(self) -> list[int]:
         """The indices of the objective qubits.
 
         Returns:
@@ -145,7 +145,7 @@ def objective_qubits(self) -> List[int]:
         return self._objective_qubits
 
     @objective_qubits.setter
-    def objective_qubits(self, objective_qubits: Optional[Union[int, List[int]]]) -> None:
+    def objective_qubits(self, objective_qubits: int | list[int] | None) -> None:
         """Set the objective qubits.
 
         Args:
@@ -170,15 +170,14 @@ def is_good_state(self) -> Callable[[str], bool]:
                 return lambda bitstr: bitstr in self._is_good_state
             else:
                 return lambda bitstr: all(
-                    bitstr[good_index] == "1"  # type:ignore
-                    for good_index in self._is_good_state
+                    bitstr[good_index] == "1" for good_index in self._is_good_state
                 )
 
         return lambda bitstr: bitstr in self._is_good_state.probabilities_dict()
 
     @is_good_state.setter
     def is_good_state(
-        self, is_good_state: Union[Callable[[str], bool], List[int], List[str], Statevector]
+        self, is_good_state: Callable[[str], bool] | list[int] | list[str] | Statevector
     ) -> None:
         """Set the ``is_good_state`` function.
 
@@ -188,7 +187,7 @@ def is_good_state(
         self._is_good_state = is_good_state
 
     @property
-    def grover_operator(self) -> Optional[QuantumCircuit]:
+    def grover_operator(self) -> QuantumCircuit | None:
         r"""Get the :math:`\mathcal{Q}` operator, or Grover operator.
 
         If the Grover operator is not set, we try to build it from the :math:`\mathcal{A}` operator
@@ -203,7 +202,7 @@ def grover_operator(self) -> Optional[QuantumCircuit]:
         return self._grover_operator
 
     @grover_operator.setter
-    def grover_operator(self, grover_operator: Optional[QuantumCircuit]) -> None:
+    def grover_operator(self, grover_operator: QuantumCircuit | None) -> None:
         r"""Set the :math:`\mathcal{Q}` operator.
 
         If None, this operator is constructed from the ``oracle`` and ``state_preparation``.

qiskit/algorithms/amplitude_amplifiers/amplitude_amplifier.py

@@ -11,9 +11,10 @@
 # that they have been altered from the originals.
 
 """The interface for amplification algorithms and results."""
+from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from typing import Optional, Any, Union, Dict, List
+from typing import Any
 
 import numpy as np
 
@@ -43,14 +44,14 @@ class AmplitudeAmplifierResult(AlgorithmResult):
 
     def __init__(self) -> None:
         super().__init__()
-        self._top_measurement = None
+        self._top_measurement: str | None = None
         self._assignment = None
-        self._oracle_evaluation = None
-        self._circuit_results = None
-        self._max_probability = None
+        self._oracle_evaluation: bool | None = None
+        self._circuit_results: list[np.ndarray] | list[dict[str, int]] | None = None
+        self._max_probability: float | None = None
 
     @property
-    def top_measurement(self) -> Optional[str]:
+    def top_measurement(self) -> str | None:
         """The most frequently measured output as bitstring.
 
         Returns:
@@ -106,12 +107,12 @@ def oracle_evaluation(self, value: bool) -> None:
         self._oracle_evaluation = value
 
     @property
-    def circuit_results(self) -> Optional[Union[List[np.ndarray], List[Dict[str, int]]]]:
+    def circuit_results(self) -> list[np.ndarray] | list[dict[str, int]] | None:
         """Return the circuit results. Can be a statevector or counts dictionary."""
         return self._circuit_results
 
     @circuit_results.setter
-    def circuit_results(self, value: Union[List[np.ndarray], List[Dict[str, int]]]) -> None:
+    def circuit_results(self, value: list[np.ndarray] | list[dict[str, int]]) -> None:
         """Set the circuit results."""
         self._circuit_results = value
 

qiskit/algorithms/amplitude_amplifiers/grover.py

@@ -11,19 +11,21 @@
 # that they have been altered from the originals.
 
 """Grover's search algorithm."""
+from __future__ import annotations
 
 import itertools
 import operator
 import warnings
-from typing import Iterator, List, Optional, Union
+from collections.abc import Iterator, Generator
+from typing import Any
 
 import numpy as np
 
 from qiskit import ClassicalRegister, QuantumCircuit
 from qiskit.algorithms.exceptions import AlgorithmError
 from qiskit.primitives import BaseSampler
 from qiskit.providers import Backend
-from qiskit.quantum_info import partial_trace
+from qiskit.quantum_info import partial_trace, Statevector
 from qiskit.utils import QuantumInstance, algorithm_globals
 from qiskit.utils.deprecation import deprecate_arg, deprecate_func
 
@@ -120,11 +122,11 @@ class Grover(AmplitudeAmplifier):
     )
     def __init__(
         self,
-        iterations: Optional[Union[List[int], Iterator[int], int]] = None,
-        growth_rate: Optional[float] = None,
+        iterations: list[int] | Iterator[int] | int | None = None,
+        growth_rate: float | None = None,
         sample_from_iterations: bool = False,
-        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
-        sampler: Optional[BaseSampler] = None,
+        quantum_instance: QuantumInstance | Backend | None = None,
+        sampler: BaseSampler | None = None,
     ) -> None:
         r"""
         Args:
@@ -163,7 +165,9 @@ def __init__(
 
         if growth_rate is not None:
             # yield iterations ** 1, iterations ** 2, etc. and casts to int
-            self._iterations = (int(growth_rate**x) for x in itertools.count(1))
+            self._iterations: Generator[int, None, None] | list[int] = (
+                int(growth_rate**x) for x in itertools.count(1)
+            )
         elif isinstance(iterations, int):
             self._iterations = [iterations]
         else:
@@ -178,7 +182,7 @@ def __init__(
             sampler = quantum_instance
             quantum_instance = None
 
-        self._quantum_instance = None
+        self._quantum_instance: QuantumInstance | None = None
         if quantum_instance is not None:
             with warnings.catch_warnings():
                 warnings.simplefilter("ignore", category=PendingDeprecationWarning)
@@ -191,7 +195,7 @@ def __init__(
 
     @property
     @deprecate_func(since="0.23.0", pending=True, is_property=True)
-    def quantum_instance(self) -> Optional[QuantumInstance]:
+    def quantum_instance(self) -> QuantumInstance | None:
         r"""Pending deprecation\; Get the quantum instance.
 
         Returns:
@@ -201,7 +205,7 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
 
     @quantum_instance.setter
     @deprecate_func(since="0.23.0", pending=True, is_property=True)
-    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
+    def quantum_instance(self, quantum_instance: QuantumInstance | Backend) -> None:
         r"""Pending deprecation\; Set quantum instance.
 
         Args:
@@ -212,7 +216,7 @@ def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) ->
         self._quantum_instance = quantum_instance
 
     @property
-    def sampler(self) -> Optional[BaseSampler]:
+    def sampler(self) -> BaseSampler | None:
         """Get the sampler.
 
         Returns:
@@ -254,7 +258,7 @@ def amplify(self, amplification_problem: AmplificationProblem) -> "GroverResult"
         if isinstance(self._iterations, list):
             max_iterations = len(self._iterations)
             max_power = np.inf  # no cap on the power
-            iterator = iter(self._iterations)
+            iterator: Iterator[int] = iter(self._iterations)
         else:
             max_iterations = max(10, 2**amplification_problem.oracle.num_qubits)
             max_power = np.ceil(
@@ -282,7 +286,7 @@ def amplify(self, amplification_problem: AmplificationProblem) -> "GroverResult"
 
             # sample from [0, power) if specified
             if self._sample_from_iterations:
-                power = algorithm_globals.random.randint(power)
+                power = algorithm_globals.random.integers(power)
             # Run a grover experiment for a given power of the Grover operator.
             if self._sampler is not None:
                 qc = self.construct_circuit(amplification_problem, power, measurement=True)
@@ -294,7 +298,7 @@ def amplify(self, amplification_problem: AmplificationProblem) -> "GroverResult"
                     raise AlgorithmError("Sampler job failed.") from exc
 
                 num_bits = len(amplification_problem.objective_qubits)
-                circuit_results = {
+                circuit_results: dict[str, Any] | Statevector | np.ndarray = {
                     np.binary_repr(k, num_bits): v for k, v in results.quasi_dists[0].items()
                 }
                 top_measurement, max_probability = max(circuit_results.items(), key=lambda x: x[1])
@@ -373,7 +377,7 @@ def optimal_num_iterations(num_solutions: int, num_qubits: int) -> int:
         return round(np.arccos(amplitude) / (2 * np.arcsin(amplitude)))
 
     def construct_circuit(
-        self, problem: AmplificationProblem, power: Optional[int] = None, measurement: bool = False
+        self, problem: AmplificationProblem, power: int | None = None, measurement: bool = False
     ) -> QuantumCircuit:
         """Construct the circuit for Grover's algorithm with ``power`` Grover operators.
 
@@ -412,10 +416,10 @@ class GroverResult(AmplitudeAmplifierResult):
 
     def __init__(self) -> None:
         super().__init__()
-        self._iterations = None
+        self._iterations: list[int] | None = None
 
     @property
-    def iterations(self) -> List[int]:
+    def iterations(self) -> list[int]:
         """All the powers of the Grover operator that have been tried.
 
         Returns:
@@ -424,7 +428,7 @@ def iterations(self) -> List[int]:
         return self._iterations
 
     @iterations.setter
-    def iterations(self, value: List[int]) -> None:
+    def iterations(self, value: list[int]) -> None:
         """Set the powers of the Grover operator that have been tried.
 
         Args:

qiskit/algorithms/amplitude_estimators/ae.py

@@ -187,7 +187,7 @@ def evaluate_measurements(
         self,
         circuit_results: dict[str, int] | np.ndarray,
         threshold: float = 1e-6,
-    ) -> tuple[dict[int, float], dict[float, float]]:
+    ) -> tuple[dict[float, float], dict[int, float]]:
         """Evaluate the results from the circuit simulation.
 
         Given the probabilities from statevector simulation of the QAE circuit, compute the
@@ -249,10 +249,10 @@ def _evaluate_quasi_probabilities_results(self, circuit_results):
 
         return samples, measurements
 
-    def _evaluate_count_results(self, counts):
+    def _evaluate_count_results(self, counts) -> tuple[dict[float, float], dict[int, float]]:
         # construct probabilities
-        measurements = OrderedDict()
-        samples = OrderedDict()
+        measurements: dict[int, float] = OrderedDict()
+        samples: dict[float, float] = OrderedDict()
         shots = sum(counts.values())
         for state, count in counts.items():
             y = int(state.replace(" ", "")[: self._m][::-1], 2)
@@ -405,7 +405,7 @@ def estimate(self, estimation_problem: EstimationProblem) -> "AmplitudeEstimatio
         # store the number of oracle queries
         result.num_oracle_queries = result.shots * (self._M - 1)
 
-        # run the MLE post processing
+        # run the MLE post-processing
         mle = self.compute_mle(result)
         result.mle = mle
         result.mle_processed = estimation_problem.post_processing(mle)
@@ -457,13 +457,13 @@ class AmplitudeEstimationResult(AmplitudeEstimatorResult):
 
     def __init__(self) -> None:
         super().__init__()
-        self._num_evaluation_qubits = None
-        self._mle = None
-        self._mle_processed = None
-        self._samples = None
-        self._samples_processed = None
-        self._y_measurements = None
-        self._max_probability = None
+        self._num_evaluation_qubits: int | None = None
+        self._mle: float | None = None
+        self._mle_processed: float | None = None
+        self._samples: dict[float, float] | None = None
+        self._samples_processed: dict[float, float] | None = None
+        self._y_measurements: dict[int, float] | None = None
+        self._max_probability: float | None = None
 
     @property
     def num_evaluation_qubits(self) -> int:
@@ -571,7 +571,7 @@ def integrand(x):
 
 def _fisher_confint(
     result: AmplitudeEstimationResult, alpha: float, observed: bool = False
-) -> list[float]:
+) -> tuple[float, float]:
     """Compute the Fisher information confidence interval for the MLE of the previous run.
 
     Args:
@@ -588,10 +588,12 @@ def _fisher_confint(
     confint = result.mle + norm.ppf(1 - alpha / 2) / std * np.array([-1, 1])
 
     # transform the confidence interval from [0, 1] to the target interval
-    return tuple(result.post_processing(bound) for bound in confint)
+    return result.post_processing(confint[0]), result.post_processing(confint[1])
 
 
-def _likelihood_ratio_confint(result: AmplitudeEstimationResult, alpha: float) -> list[float]:
+def _likelihood_ratio_confint(
+    result: AmplitudeEstimationResult, alpha: float
+) -> tuple[float, float]:
     """Compute the likelihood ratio confidence interval for the MLE of the previous run.
 
     Args:
@@ -659,5 +661,4 @@ def cut(x):
                 upper = np.maximum(upper, right)
 
     # Put together CI
-    confint = [lower, upper]
-    return tuple(result.post_processing(bound) for bound in confint)
+    return result.post_processing(lower), result.post_processing(upper)