[pre-commit.ci] auto fixes from pre-commit.com hooks

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src/qibo/transpiler/router.py

@@ -176,24 +176,26 @@ def __init__(
         initial_layout: dict,
         circuit: Optional[Circuit] = None,
         blocks: Optional[CircuitBlocks] = None,
-        temp: Optional[bool] = False,           #2# for temporary circuit
+        temp: Optional[bool] = False,  # 2# for temporary circuit
     ):
         self.initial_layout = dict(sorted(initial_layout.items()))
 
-        #1# bidirectional mapping
-        #1# self._p2l: physical qubit number i -> logical qubit number _p2l[i]
-        #1# self._l2p: logical qubit number i -> physical qubit number _l2p[i]
-        self._l2p, self._p2l = [0] * len(self.initial_layout), [0] * len(self.initial_layout)
+        # 1# bidirectional mapping
+        # 1# self._p2l: physical qubit number i -> logical qubit number _p2l[i]
+        # 1# self._l2p: logical qubit number i -> physical qubit number _l2p[i]
+        self._l2p, self._p2l = [0] * len(self.initial_layout), [0] * len(
+            self.initial_layout
+        )
         for mapping in self.initial_layout.items():
             physical_qubit, logical_qubit = int(mapping[0][1:]), mapping[1]
             self._l2p[logical_qubit] = physical_qubit
             self._p2l[physical_qubit] = logical_qubit
 
         self._temporary = temp
-        if self._temporary:     #2# if temporary circuit, no need to store the blocks
+        if self._temporary:  # 2# if temporary circuit, no need to store the blocks
             return
 
-        self._nqubits = circuit.nqubits         #1# number of qubits
+        self._nqubits = circuit.nqubits  # 1# number of qubits
         if circuit is None:
             raise_error(ValueError, "Circuit must be provided.")
 
@@ -205,7 +207,7 @@ def __init__(
         self._routed_blocks = CircuitBlocks(Circuit(circuit.nqubits))
         self._swaps = 0
 
-    #1# previous: set_circuit_logical
+    # 1# previous: set_circuit_logical
     def set_p2l(self, p2l_map: list):
         """Sets the current physical to logical qubit mapping.
 
@@ -214,8 +216,8 @@ def set_p2l(self, p2l_map: list):
         Args:
             p2l_map (list): physical to logical mapping.
         """
-        #1# update bidirectional mapping
-        #4# use shallow copy
+        # 1# update bidirectional mapping
+        # 4# use shallow copy
         self._p2l = p2l_map.copy()
         self._l2p = [0] * len(self._p2l)
         for i, l in enumerate(self._p2l):
@@ -234,9 +236,7 @@ def execute_block(self, block: Block):
         Args:
             block (:class:`qibo.transpiler.blocks.Block`): block to be removed.
         """
-        self._routed_blocks.add_block(
-            block.on_qubits(self.get_physical_qubits(block))
-        )
+        self._routed_blocks.add_block(block.on_qubits(self.get_physical_qubits(block)))
         self.circuit_blocks.remove_block(block)
 
     def routed_circuit(self, circuit_kwargs: Optional[dict] = None):
@@ -253,11 +253,8 @@ def routed_circuit(self, circuit_kwargs: Optional[dict] = None):
     def final_layout(self):
         """Returns the final physical-logical qubits mapping."""
 
-        #1# return {"q0": lq_num0, "q1": lq_num1, ...}
-        unsorted_dict = {
-            "q" + str(i): self._p2l[i]
-            for i in range(self._nqubits)
-        }
+        # 1# return {"q0": lq_num0, "q1": lq_num1, ...}
+        unsorted_dict = {"q" + str(i): self._p2l[i] for i in range(self._nqubits)}
 
         return dict(sorted(unsorted_dict.items()))
 
@@ -273,14 +270,14 @@ def update(self, swap_l: tuple):
 
         swap_p = self.logical_pair_to_physical(swap_l)
 
-        #2# add the real SWAP gate, not a temporary circuit
+        # 2# add the real SWAP gate, not a temporary circuit
         if not self._temporary:
             self._routed_blocks.add_block(
                 Block(qubits=swap_p, gates=[gates.SWAP(*swap_p)])
             )
             self._swaps += 1
 
-        #1# update the bidirectional mapping
+        # 1# update the bidirectional mapping
         p1, p2 = swap_p
         l1, l2 = swap_l
         self._p2l[p1], self._p2l[p2] = l2, l1
@@ -294,7 +291,7 @@ def undo(self):
         self._routed_blocks.remove_block(last_swap_block)
         self._swaps -= 1
 
-        #1# update the bidirectional mapping
+        # 1# update the bidirectional mapping
         p1, p2 = swap_p
         l1, l2 = swap_l
         self._p2l[p1], self._p2l[p2] = l2, l1
@@ -314,7 +311,7 @@ def get_physical_qubits(self, block: Union[int, Block]):
 
         return tuple(self._l2p[q] for q in block.qubits)
 
-    #1# logical_to_physical -> logical_pair_to_physical
+    # 1# logical_to_physical -> logical_pair_to_physical
     def logical_pair_to_physical(self, logical_qubits: tuple):
         """Returns the physical qubits associated to the logical qubit pair.
 
@@ -324,10 +321,11 @@ def logical_pair_to_physical(self, logical_qubits: tuple):
         Returns:
             tuple: physical qubit numbers associated to the logical qubit pair.
         """
-        #1# return physical qubit numbers corresponding to the logical qubit pair
+        # 1# return physical qubit numbers corresponding to the logical qubit pair
         return self._l2p[logical_qubits[0]], self._l2p[logical_qubits[1]]
 
-    #1# circuit_to_logical(), circuit_to_physical() removed
+    # 1# circuit_to_logical(), circuit_to_physical() removed
+
 
 class ShortestPaths(Router):
     """A class to perform initial qubit mapping and connectivity matching.
@@ -382,9 +380,12 @@ def __call__(self, circuit: Circuit, initial_layout: dict):
                 routed_circuit=routed_circuit
             )
 
-        #1# final layout is reverted to the original labeling 
+        # 1# final layout is reverted to the original labeling
         final_layout = self.circuit.final_layout()
-        final_layout_restored = {"q" + str(self.node_mapping_inv[int(k[1:])]): v for k, v in final_layout.items()}
+        final_layout_restored = {
+            "q" + str(self.node_mapping_inv[int(k[1:])]): v
+            for k, v in final_layout.items()
+        }
         return routed_circuit, final_layout_restored
 
     def _find_new_mapping(self):
@@ -434,15 +435,14 @@ def _add_swaps(candidate: tuple, circuitmap: CircuitMap):
         """
         path = candidate[0]
         meeting_point = candidate[1]
-        forward = path[0 : meeting_point + 1]       #1# physical qubits
+        forward = path[0 : meeting_point + 1]  # 1# physical qubits
         backward = list(reversed(path[meeting_point + 1 :]))
-        #1# apply logical swaps 
+        # 1# apply logical swaps
         for f in forward[1:]:
             circuitmap.update((circuitmap._p2l[f], circuitmap._p2l[forward[0]]))
         for b in backward[1:]:
             circuitmap.update((circuitmap._p2l[b], circuitmap._p2l[backward[0]]))
 
-
     def _compute_cost(self, candidate: tuple):
         """Greedy algorithm that decides which path to take and how qubits should be walked.
 
@@ -454,14 +454,14 @@ def _compute_cost(self, candidate: tuple):
         Returns:
             (list, int): best path to move qubits and qubit meeting point in the path.
         """
-        #2# CircuitMap might be used
+        # 2# CircuitMap might be used
         temporary_circuit = CircuitMap(
             initial_layout=self.circuit.initial_layout,
             circuit=Circuit(len(self.circuit.initial_layout)),
             blocks=deepcopy(self.circuit.circuit_blocks),
         )
 
-        #1# use set_p2l
+        # 1# use set_p2l
         temporary_circuit.set_p2l(self.circuit._p2l)
         self._add_swaps(candidate, temporary_circuit)
         temporary_dag = deepcopy(self._dag)
@@ -476,7 +476,7 @@ def _compute_cost(self, candidate: tuple):
             all_executed = True
             for block in temporary_front_layer:
                 if (
-                    #3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
+                    # 3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
                     temporary_circuit.get_physical_qubits(block)
                     in self.connectivity.edges
                     or not temporary_circuit.circuit_blocks.search_by_index(
@@ -504,7 +504,7 @@ def _check_execution(self):
         executable_blocks = []
         for block in self._front_layer:
             if (
-                #3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
+                # 3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
                 self.circuit.get_physical_qubits(block) in self.connectivity.edges
                 or not self.circuit.circuit_blocks.search_by_index(block).entangled
             ):
@@ -554,7 +554,7 @@ def _preprocessing(self, circuit: Circuit, initial_layout: dict):
             initial_layout (dict): initial physical-to-logical qubit mapping.
         """
 
-        #1# To simplify routing, some data is relabeled before routing begins.
+        # 1# To simplify routing, some data is relabeled before routing begins.
         node_mapping, new_initial_layout = {}, {}
         for i, node in enumerate(self.connectivity.nodes):
             node_mapping[node] = i
@@ -596,8 +596,9 @@ def _append_final_measurements(self, routed_circuit: Circuit):
         for measurement in self._final_measurements:
             original_qubits = measurement.qubits
             routed_qubits = list(
-                #1# use l2p to get physical qubit numbers
-                self.circuit._l2p[qubit] for qubit in original_qubits
+                # 1# use l2p to get physical qubit numbers
+                self.circuit._l2p[qubit]
+                for qubit in original_qubits
             )
             routed_circuit.add(
                 measurement.on_qubits(dict(zip(original_qubits, routed_qubits)))
@@ -643,7 +644,7 @@ def __init__(
         seed: Optional[int] = None,
     ):
         self.connectivity = connectivity
-        #1# map to revert the final layout to the original labeling
+        # 1# map to revert the final layout to the original labeling
         self.node_mapping_inv = None
         self.lookahead = lookahead
         self.decay = decay_lookahead
@@ -698,9 +699,12 @@ def __call__(self, circuit: Circuit, initial_layout: dict):
                 routed_circuit=routed_circuit
             )
 
-        #1# final layout is reverted to the original labeling
+        # 1# final layout is reverted to the original labeling
         final_layout = self.circuit.final_layout()
-        final_layout_restored = {"q" + str(self.node_mapping_inv[int(k[1:])]): v for k, v in final_layout.items()}
+        final_layout_restored = {
+            "q" + str(self.node_mapping_inv[int(k[1:])]): v
+            for k, v in final_layout.items()
+        }
         return routed_circuit, final_layout_restored
 
     @property
@@ -724,8 +728,8 @@ def _preprocessing(self, circuit: Circuit, initial_layout: dict):
             initial_layout (dict): initial physical-to-logical qubit mapping.
         """
 
-        #1# To simplify routing, some data is relabeled before routing begins.
-        #1# physical qubit is reassigned to a range from 0 to len(self.connectivity.nodes) - 1.
+        # 1# To simplify routing, some data is relabeled before routing begins.
+        # 1# physical qubit is reassigned to a range from 0 to len(self.connectivity.nodes) - 1.
         node_mapping, new_initial_layout = {}, {}
         for i, node in enumerate(self.connectivity.nodes):
             node_mapping[node] = i
@@ -769,8 +773,9 @@ def _append_final_measurements(self, routed_circuit: Circuit):
         for measurement in self._final_measurements:
             original_qubits = measurement.qubits
             routed_qubits = list(
-                #1# use l2p to get physical qubit numbers
-                self.circuit._l2p[qubit] for qubit in original_qubits
+                # 1# use l2p to get physical qubit numbers
+                self.circuit._l2p[qubit]
+                for qubit in original_qubits
             )
             routed_circuit.add(
                 measurement.on_qubits(dict(zip(original_qubits, routed_qubits)))
@@ -799,8 +804,8 @@ def _get_dag_layer(self, n_layer, qubits=False):
         Otherwise, return the block numbers.
         """
 
-        #3# depend on the 'qubits' flag, return the block number or target qubits
-        #3# return target qubits -> to avoid using get_physical_qubits(block_num)
+        # 3# depend on the 'qubits' flag, return the block number or target qubits
+        # 3# return target qubits -> to avoid using get_physical_qubits(block_num)
         if qubits:
             layer_qubits = []
             nodes = self._dag.nodes(data=True)
@@ -816,7 +821,7 @@ def _find_new_mapping(self):
         """Find the new best mapping by adding one swap."""
         candidates_evaluation = {}
 
-        #4# use shallow copy
+        # 4# use shallow copy
         self._memory_map.append(self.circuit._p2l.copy())
         for candidate in self._swap_candidates():
             candidates_evaluation[candidate] = self._compute_cost(candidate)
@@ -835,31 +840,31 @@ def _find_new_mapping(self):
     def _compute_cost(self, candidate: int):
         """Compute the cost associated to a possible SWAP candidate."""
 
-        #2# use CircuitMap for temporary circuit to save time
-        #2# no gates, no block decomposition, no Circuit object
-        #2# just logical-physical mapping
+        # 2# use CircuitMap for temporary circuit to save time
+        # 2# no gates, no block decomposition, no Circuit object
+        # 2# just logical-physical mapping
         temporary_circuit = CircuitMap(
             initial_layout=self.circuit.initial_layout,
             temp=True,
         )
 
-        #1# use set_p2l
+        # 1# use set_p2l
         temporary_circuit.set_p2l(self.circuit._p2l)
         temporary_circuit.update(candidate)
 
-        #1# use p2l to check if the mapping is already in the memory
+        # 1# use p2l to check if the mapping is already in the memory
         if temporary_circuit._p2l in self._memory_map:
             return float("inf")
 
         tot_distance = 0.0
         weight = 1.0
         for layer in range(self.lookahead + 1):
-            #3# return gates' target qubit pairs in the layer
-            #3# to avoid using get_physical_qubits(block_num)
+            # 3# return gates' target qubit pairs in the layer
+            # 3# to avoid using get_physical_qubits(block_num)
             layer_gates = self._get_dag_layer(layer, qubits=True)
             avg_layer_distance = 0.0
             for lq_pair in layer_gates:
-                #3# logical qubit pairs to node numbers (physical qubit pairs) in the connectivity graph
+                # 3# logical qubit pairs to node numbers (physical qubit pairs) in the connectivity graph
                 qubits = temporary_circuit.logical_pair_to_physical(lq_pair)
                 avg_layer_distance += (
                     max(self._delta_register[i] for i in qubits)
@@ -881,7 +886,7 @@ def _swap_candidates(self):
             (list): list of candidates.
         """
         candidates = []
-        #3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
+        # 3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
         for block in self._front_layer:
             for qubit in self.circuit.get_physical_qubits(block):
                 for connected in self.connectivity.neighbors(qubit):
@@ -907,7 +912,7 @@ def _check_execution(self):
         executable_blocks = []
         for block in self._front_layer:
             if (
-                #3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
+                # 3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
                 self.circuit.get_physical_qubits(block) in self.connectivity.edges
                 or not self.circuit.circuit_blocks.search_by_index(block).entangled
             ):
@@ -950,8 +955,8 @@ def _shortest_path_routing(self):
         shortest_path_qubits = None
 
         for block in self._front_layer:
-            #3# return node numbers (physical qubits) in the connectivity graph
-            #3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
+            # 3# return node numbers (physical qubits) in the connectivity graph
+            # 3# might be changed to use _get_dag_layer(qubits=True) to avoid using get_physical_qubits(block_num)
             q1, q2 = self.circuit.get_physical_qubits(block)
             distance = self._dist_matrix[q1, q2]
 
@@ -964,11 +969,12 @@ def _shortest_path_routing(self):
         )
 
         # move q1
-        #1# qubit moving algorithm is changed
+        # 1# qubit moving algorithm is changed
         q1 = self.circuit._p2l[shortest_path[0]]
         for q2 in shortest_path[1:-1]:
             self.circuit.update((q1, self.circuit._p2l[q2]))
 
+
 def _create_dag(gates_qubits_pairs: list):
     """Helper method for :meth:`qibo.transpiler.router.Sabre`.
 
@@ -984,7 +990,7 @@ def _create_dag(gates_qubits_pairs: list):
     dag = nx.DiGraph()
     dag.add_nodes_from(range(len(gates_qubits_pairs)))
 
-    #3# additionally store target qubits of the gates
+    # 3# additionally store target qubits of the gates
     for i in range(len(gates_qubits_pairs)):
         dag.nodes[i]["qubits"] = gates_qubits_pairs[i]
 
@@ -1003,6 +1009,7 @@ def _create_dag(gates_qubits_pairs: list):
 
     return _remove_redundant_connections(dag)
 
+
 def _remove_redundant_connections(dag: nx.DiGraph):
     """Helper method for :func:`qibo.transpiler.router._create_dag`.
 
@@ -1015,9 +1022,9 @@ def _remove_redundant_connections(dag: nx.DiGraph):
         (:class:`networkx.DiGraph`): reduced dag.
     """
     new_dag = nx.DiGraph()
-    #3# add nodes with attributes
+    # 3# add nodes with attributes
     new_dag.add_nodes_from(dag.nodes(data=True))
     transitive_reduction = nx.transitive_reduction(dag)
     new_dag.add_edges_from(transitive_reduction.edges)
 
-    return new_dag
+    return new_dag