Revert "make circuit_key public"

This reverts commit 2923245.

qiskit/algorithms/gradients/base_estimator_gradient.py

@@ -26,7 +26,7 @@
 from qiskit.circuit import Parameter, ParameterExpression, QuantumCircuit
 from qiskit.opflow import PauliSumOp
 from qiskit.primitives import BaseEstimator
-from qiskit.primitives.utils import circuit_key
+from qiskit.primitives.utils import _circuit_key
 from qiskit.providers import Options
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 from qiskit.transpiler.passes import TranslateParameterizedGates
@@ -165,11 +165,11 @@ def _preprocess(
         for circuit, parameter_value_, parameter_set in zip(
             circuits, parameter_values, parameter_sets
         ):
-            _circuit_key = circuit_key(circuit)
-            if _circuit_key not in self._gradient_circuit_cache:
+            circuit_key = _circuit_key(circuit)
+            if circuit_key not in self._gradient_circuit_cache:
                 unrolled = translator(circuit)
-                self._gradient_circuit_cache[_circuit_key] = _assign_unique_parameters(unrolled)
-            gradient_circuit = self._gradient_circuit_cache[_circuit_key]
+                self._gradient_circuit_cache[circuit_key] = _assign_unique_parameters(unrolled)
+            gradient_circuit = self._gradient_circuit_cache[circuit_key]
             g_circuits.append(gradient_circuit.gradient_circuit)
             g_parameter_values.append(
                 _make_gradient_parameter_values(circuit, gradient_circuit, parameter_value_)
@@ -208,7 +208,7 @@ def _postprocess(
             ):
                 # If the derivative type is complex, cast the gradient to complex.
                 unique_gradient = unique_gradient.astype("complex")
-            gradient_circuit = self._gradient_circuit_cache[circuit_key(circuit)]
+            gradient_circuit = self._gradient_circuit_cache[_circuit_key(circuit)]
             g_parameter_set = _make_gradient_parameter_set(gradient_circuit, parameter_set)
             # Make a map from the gradient parameter to the respective index in the gradient.
             parameter_indices = [param for param in circuit.parameters if param in parameter_set]

qiskit/algorithms/gradients/base_sampler_gradient.py

@@ -24,7 +24,7 @@
 from qiskit.algorithms import AlgorithmJob
 from qiskit.circuit import Parameter, ParameterExpression, QuantumCircuit
 from qiskit.primitives import BaseSampler
-from qiskit.primitives.utils import circuit_key
+from qiskit.primitives.utils import _circuit_key
 from qiskit.providers import Options
 from qiskit.transpiler.passes import TranslateParameterizedGates
 
@@ -146,11 +146,11 @@ def _preprocess(
         for circuit, parameter_value_, parameter_set in zip(
             circuits, parameter_values, parameter_sets
         ):
-            _circuit_key = circuit_key(circuit)
-            if _circuit_key not in self._gradient_circuit_cache:
+            circuit_key = _circuit_key(circuit)
+            if circuit_key not in self._gradient_circuit_cache:
                 unrolled = translator(circuit)
-                self._gradient_circuit_cache[_circuit_key] = _assign_unique_parameters(unrolled)
-            gradient_circuit = self._gradient_circuit_cache[_circuit_key]
+                self._gradient_circuit_cache[circuit_key] = _assign_unique_parameters(unrolled)
+            gradient_circuit = self._gradient_circuit_cache[circuit_key]
             g_circuits.append(gradient_circuit.gradient_circuit)
             g_parameter_values.append(
                 _make_gradient_parameter_values(circuit, gradient_circuit, parameter_value_)
@@ -182,7 +182,7 @@ def _postprocess(
         for idx, (circuit, parameter_values_, parameter_set) in enumerate(
             zip(circuits, parameter_values, parameter_sets)
         ):
-            gradient_circuit = self._gradient_circuit_cache[circuit_key(circuit)]
+            gradient_circuit = self._gradient_circuit_cache[_circuit_key(circuit)]
             g_parameter_set = _make_gradient_parameter_set(gradient_circuit, parameter_set)
             # Make a map from the gradient parameter to the respective index in the gradient.
             parameter_indices = [param for param in circuit.parameters if param in parameter_set]

qiskit/algorithms/gradients/lin_comb_estimator_gradient.py

@@ -23,7 +23,7 @@
 from qiskit.circuit import Parameter, QuantumCircuit
 from qiskit.opflow import PauliSumOp
 from qiskit.primitives import BaseEstimator
-from qiskit.primitives.utils import init_observable, circuit_key
+from qiskit.primitives.utils import init_observable, _circuit_key
 from qiskit.providers import Options
 from qiskit.quantum_info import SparsePauliOp
 from qiskit.quantum_info.operators.base_operator import BaseOperator
@@ -124,12 +124,12 @@ def _run_unique(
         ):
             # Prepare circuits for the gradient of the specified parameters.
             meta = {"parameters": [p for p in circuit.parameters if p in parameter_set]}
-            _circuit_key = circuit_key(circuit)
-            if _circuit_key not in self._lin_comb_cache:
-                self._lin_comb_cache[_circuit_key] = _make_lin_comb_gradient_circuit(
+            circuit_key = _circuit_key(circuit)
+            if circuit_key not in self._lin_comb_cache:
+                self._lin_comb_cache[circuit_key] = _make_lin_comb_gradient_circuit(
                     circuit, add_measurement=False
                 )
-            lin_comb_circuits = self._lin_comb_cache[_circuit_key]
+            lin_comb_circuits = self._lin_comb_cache[circuit_key]
             gradient_circuits = []
             for param in circuit.parameters:
                 if param not in parameter_set:

qiskit/algorithms/gradients/lin_comb_qfi.py

@@ -23,7 +23,7 @@
 from qiskit.algorithms import AlgorithmError
 from qiskit.circuit import Parameter, ParameterExpression, QuantumCircuit
 from qiskit.primitives import BaseEstimator
-from qiskit.primitives.utils import circuit_key
+from qiskit.primitives.utils import _circuit_key
 from qiskit.providers import Options
 from qiskit.quantum_info import SparsePauliOp
 
@@ -138,13 +138,13 @@ def _run(
                 )
                 gradient_jobs.append(gradient_job)
             # compute the first term in the QFI
-            qfi_circuits_ = self._qfi_circuit_cache.get(circuit_key(circuit))
+            qfi_circuits_ = self._qfi_circuit_cache.get(_circuit_key(circuit))
             if qfi_circuits_ is None:
                 # generate the all of the circuits for the first term in the QFI and cache them.
                 # only the circuit related to specified parameters will be executed.
                 # In the future, we can generate the specified circuits on demand.
                 qfi_circuits_ = _make_lin_comb_qfi_circuit(circuit)
-                self._qfi_circuit_cache[circuit_key(circuit)] = qfi_circuits_
+                self._qfi_circuit_cache[_circuit_key(circuit)] = qfi_circuits_
 
             # only compute the gradients for parameters in the parameter set
             qfi_circuits, result_indices, coeffs = [], [], []

qiskit/algorithms/gradients/lin_comb_sampler_gradient.py

@@ -21,7 +21,7 @@
 from qiskit.algorithms import AlgorithmError
 from qiskit.circuit import Parameter, QuantumCircuit
 from qiskit.primitives import BaseSampler
-from qiskit.primitives.utils import circuit_key
+from qiskit.primitives.utils import _circuit_key
 from qiskit.providers import Options
 
 from .base_sampler_gradient import BaseSamplerGradient
@@ -103,12 +103,12 @@ def _run_unique(
             # Prepare circuits for the gradient of the specified parameters.
             meta = {"parameters": [p for p in circuit.parameters if p in parameter_set]}
             metadata.append(meta)
-            _circuit_key = circuit_key(circuit)
-            if _circuit_key not in self._lin_comb_cache:
-                self._lin_comb_cache[_circuit_key] = _make_lin_comb_gradient_circuit(
+            circuit_key = _circuit_key(circuit)
+            if circuit_key not in self._lin_comb_cache:
+                self._lin_comb_cache[circuit_key] = _make_lin_comb_gradient_circuit(
                     circuit, add_measurement=True
                 )
-            lin_comb_circuits = self._lin_comb_cache[_circuit_key]
+            lin_comb_circuits = self._lin_comb_cache[circuit_key]
             gradient_circuits = []
             for param in circuit.parameters:
                 if param not in parameter_set:

qiskit/algorithms/minimum_eigensolvers/diagonal_estimator.py

@@ -23,7 +23,7 @@
 from qiskit.algorithms.algorithm_job import AlgorithmJob
 from qiskit.circuit import QuantumCircuit
 from qiskit.primitives import BaseSampler, BaseEstimator, EstimatorResult
-from qiskit.primitives.utils import init_observable, circuit_key
+from qiskit.primitives.utils import init_observable, _circuit_key
 from qiskit.opflow import PauliSumOp
 from qiskit.quantum_info import SparsePauliOp
 from qiskit.quantum_info.operators.base_operator import BaseOperator
@@ -75,7 +75,7 @@ def _run(
     ) -> AlgorithmJob:
         circuit_indices = []
         for circuit in circuits:
-            key = circuit_key(circuit)
+            key = _circuit_key(circuit)
             index = self._circuit_ids.get(key)
             if index is not None:
                 circuit_indices.append(index)

qiskit/primitives/backend_estimator.py

@@ -32,7 +32,7 @@
 
 from .base import BaseEstimator, EstimatorResult
 from .primitive_job import PrimitiveJob
-from .utils import circuit_key, _observable_key, init_observable
+from .utils import _circuit_key, _observable_key, init_observable
 
 
 def _run_circuits(
@@ -267,12 +267,12 @@ def _run(
     ) -> PrimitiveJob:
         circuit_indices = []
         for circuit in circuits:
-            index = self._circuit_ids.get(circuit_key(circuit))
+            index = self._circuit_ids.get(_circuit_key(circuit))
             if index is not None:
                 circuit_indices.append(index)
             else:
                 circuit_indices.append(len(self._circuits))
-                self._circuit_ids[circuit_key(circuit)] = len(self._circuits)
+                self._circuit_ids[_circuit_key(circuit)] = len(self._circuits)
                 self._circuits.append(circuit)
                 self._parameters.append(circuit.parameters)
         observable_indices = []

qiskit/primitives/backend_sampler.py

@@ -26,7 +26,7 @@
 from .backend_estimator import _prepare_counts, _run_circuits
 from .base import BaseSampler, SamplerResult
 from .primitive_job import PrimitiveJob
-from .utils import circuit_key
+from .utils import _circuit_key
 
 
 class BackendSampler(BaseSampler):
@@ -197,12 +197,12 @@ def _run(
     ) -> PrimitiveJob:
         circuit_indices = []
         for circuit in circuits:
-            index = self._circuit_ids.get(circuit_key(circuit))
+            index = self._circuit_ids.get(_circuit_key(circuit))
             if index is not None:
                 circuit_indices.append(index)
             else:
                 circuit_indices.append(len(self._circuits))
-                self._circuit_ids[circuit_key(circuit)] = len(self._circuits)
+                self._circuit_ids[_circuit_key(circuit)] = len(self._circuits)
                 self._circuits.append(circuit)
                 self._parameters.append(circuit.parameters)
         job = PrimitiveJob(self._call, circuit_indices, parameter_values, **run_options)

qiskit/primitives/base/base_estimator.py

@@ -98,7 +98,7 @@
 
 from .base_primitive import BasePrimitive
 from .estimator_result import EstimatorResult
-from ..utils import circuit_key, _observable_key, init_observable
+from ..utils import _circuit_key, _observable_key, init_observable
 
 
 class BaseEstimator(BasePrimitive):
@@ -297,9 +297,9 @@ def __new__(
             self._circuit_ids = {}
         elif isinstance(circuits, Iterable):
             circuits = copy(circuits)
-            self._circuit_ids = {circuit_key(circuit): i for i, circuit in enumerate(circuits)}
+            self._circuit_ids = {_circuit_key(circuit): i for i, circuit in enumerate(circuits)}
         else:
-            self._circuit_ids = {circuit_key(circuits): 0}
+            self._circuit_ids = {_circuit_key(circuits): 0}
         if observables is None:
             self._observable_ids = {}
         elif isinstance(observables, Iterable):
@@ -413,7 +413,7 @@ def __call__(
 
         # Allow objects
         circuits = [
-            self._circuit_ids.get(circuit_key(circuit))
+            self._circuit_ids.get(_circuit_key(circuit))
             if not isinstance(circuit, (int, np.integer))
             else circuit
             for circuit in circuits

qiskit/primitives/base/base_sampler.py

@@ -90,7 +90,7 @@
 
 from .base_primitive import BasePrimitive
 from .sampler_result import SamplerResult
-from ..utils import circuit_key
+from ..utils import _circuit_key
 
 
 class BaseSampler(BasePrimitive):
@@ -233,9 +233,9 @@ def __new__(
             self._circuit_ids = {}
         elif isinstance(circuits, Iterable):
             circuits = copy(circuits)
-            self._circuit_ids = {circuit_key(circuit): i for i, circuit in enumerate(circuits)}
+            self._circuit_ids = {_circuit_key(circuit): i for i, circuit in enumerate(circuits)}
         else:
-            self._circuit_ids = {circuit_key(circuits): 0}
+            self._circuit_ids = {_circuit_key(circuits): 0}
         return self
 
     @property
@@ -310,7 +310,7 @@ def __call__(
 
         # Allow objects
         circuits = [
-            self._circuit_ids.get(circuit_key(circuit))
+            self._circuit_ids.get(_circuit_key(circuit))
             if not isinstance(circuit, (int, np.integer))
             else circuit
             for circuit in circuits

qiskit/primitives/estimator.py

@@ -29,7 +29,7 @@
 from .base import BaseEstimator, EstimatorResult
 from .primitive_job import PrimitiveJob
 from .utils import (
-    circuit_key,
+    _circuit_key,
     _observable_key,
     bound_circuit_to_instruction,
     init_circuit,
@@ -161,7 +161,7 @@ def _run(
     ) -> PrimitiveJob:
         circuit_indices = []
         for circuit in circuits:
-            key = circuit_key(circuit)
+            key = _circuit_key(circuit)
             index = self._circuit_ids.get(key)
             if index is not None:
                 circuit_indices.append(index)

qiskit/primitives/sampler.py

@@ -28,7 +28,7 @@
 from .base import BaseSampler, SamplerResult
 from .primitive_job import PrimitiveJob
 from .utils import (
-    circuit_key,
+    _circuit_key,
     bound_circuit_to_instruction,
     final_measurement_mapping,
     init_circuit,
@@ -142,7 +142,7 @@ def _run(
     ) -> PrimitiveJob:
         circuit_indices = []
         for circuit in circuits:
-            key = circuit_key(circuit)
+            key = _circuit_key(circuit)
             index = self._circuit_ids.get(key)
             if index is not None:
                 circuit_indices.append(index)

qiskit/primitives/utils.py

@@ -129,14 +129,14 @@ def _format_params(param):
     if isinstance(param, np.ndarray):
         return param.data.tobytes()
     elif isinstance(param, QuantumCircuit):
-        return circuit_key(param)
+        return _circuit_key(param)
     elif isinstance(param, Iterable):
         return tuple(param)
     return param
 
 
-def circuit_key(circuit: QuantumCircuit, functional: bool = True) -> tuple:
-    """Hashable serializable key function for QuantumCircuit.
+def _circuit_key(circuit: QuantumCircuit, functional: bool = True) -> tuple:
+    """Private key function for QuantumCircuit.
 
     This is the workaround until :meth:`QuantumCircuit.__hash__` will be introduced.
     If key collision is found, please add elements to avoid it.

test/python/primitives/test_primitive.py

@@ -20,7 +20,7 @@
 from qiskit import QuantumCircuit, pulse, transpile
 from qiskit.circuit.random import random_circuit
 from qiskit.primitives.base.base_primitive import BasePrimitive
-from qiskit.primitives.utils import circuit_key
+from qiskit.primitives.utils import _circuit_key
 from qiskit.providers.fake_provider import FakeAlmaden
 from qiskit.test import QiskitTestCase
 
@@ -129,7 +129,7 @@ def test_func(n):
                 qc.ry(n, 0)
                 return qc
 
-            keys = [circuit_key(test_func(i)) for i in range(5)]
+            keys = [_circuit_key(test_func(i)) for i in range(5)]
             self.assertEqual(len(keys), len(set(keys)))
 
         with self.subTest("pulse circuit"):
@@ -144,7 +144,7 @@ def test_with_scheduling(n):
                 qc.add_calibration("x", qubits=(0,), schedule=custom_gate)
                 return transpile(qc, FakeAlmaden(), scheduling_method="alap")
 
-            keys = [circuit_key(test_with_scheduling(i)) for i in range(1, 5)]
+            keys = [_circuit_key(test_with_scheduling(i)) for i in range(1, 5)]
             self.assertEqual(len(keys), len(set(keys)))
 
     def test_circuit_key_controlflow(self):
@@ -157,5 +157,5 @@ def test_circuit_key_controlflow(self):
             qc.measure(0, 0)
             qc.break_loop().c_if(0, True)
 
-        self.assertIsInstance(hash(circuit_key(qc)), int)
-        self.assertIsInstance(json.dumps(circuit_key(qc)), str)
+        self.assertIsInstance(hash(_circuit_key(qc)), int)
+        self.assertIsInstance(json.dumps(_circuit_key(qc)), str)