qiskit/transpiler/passes/mapping/basic_swap.py
def run(self, dag):
        """
        Runs the BasicSwap pass on `dag`.
        Args:
            dag (DAGCircuit): DAG to map.

        Returns:
            DAGCircuit: A mapped DAG.

        Raises:
            TranspilerError: if the coupling map or the layout are not
            compatible with the DAG
        """
        new_dag = DAGCircuit()

        if self.initial_layout is None:
            if self.property_set["layout"]:
                self.initial_layout = self.property_set["layout"]
            else:
                self.initial_layout = Layout.generate_trivial_layout(*dag.qregs.values())

        if len(dag.qubits()) != len(self.initial_layout):
            raise TranspilerError('The layout does not match the amount of qubits in the DAG')

        if len(self.coupling_map.physical_qubits) != len(self.initial_layout):
            raise TranspilerError(
                "Mappers require to have the layout to be the same size as the coupling map")

        current_layout = self.initial_layout.copy()

        for layer in dag.serial_layers():
            subdag = layer['graph']

            for gate in subdag.twoQ_gates():
                physical_q0 = current_layout[gate.qargs[0]]
                physical_q1 = current_layout[gate.qargs[1]]
                if self.coupling_map.distance(physical_q0, physical_q1) != 1:
                    # Insert a new layer with the SWAP(s).
                    swap_layer = DAGCircuit()

                    path = self.coupling_map.shortest_undirected_path(physical_q0, physical_q1)
                    for swap in range(len(path) - 2):
                        connected_wire_1 = path[swap]
                        connected_wire_2 = path[swap + 1]

                        qubit_1 = current_layout[connected_wire_1]
                        qubit_2 = current_layout[connected_wire_2]

                        # create qregs
                        for qreg in current_layout.get_registers():
                            if qreg not in swap_layer.qregs.values():
                                swap_layer.add_qreg(qreg)

                        # create the swap operation
                        swap_layer.apply_operation_back(SwapGate(),
                                                        qargs=[qubit_1, qubit_2],
                                                        cargs=[])

                    # layer insertion
                    edge_map = current_layout.combine_into_edge_map(self.initial_layout)
                    new_dag.compose_back(swap_layer, edge_map)

                    # update current_layout
                    for swap in range(len(path) - 2):
                        current_layout.swap(path[swap], path[swap + 1])

            edge_map = current_layout.combine_into_edge_map(self.initial_layout)
            new_dag.extend_back(subdag, edge_map)

        return new_dag
def run(self, dag):
        """
        Runs the BasicSwap pass on `dag`.
        Args:
            dag (DAGCircuit): DAG to map.

        Returns:
            DAGCircuit: A mapped DAG.

        Raises:
            TranspilerError: if the coupling map or the layout are not
            compatible with the DAG
        """
        new_dag = DAGCircuit()

        if self.initial_layout is None:
            if self.property_set["layout"]:
                self.initial_layout = self.property_set["layout"]
            else:
                self.initial_layout = Layout.generate_trivial_layout(*dag.qregs.values())

        if len(dag.qubits()) != len(self.initial_layout):
            raise TranspilerError('The layout does not match the amount of qubits in the DAG')

        if len(self.coupling_map.physical_qubits) != len(self.initial_layout):
            raise TranspilerError(
                "Mappers require to have the layout to be the same size as the coupling map")

        current_layout = self.initial_layout.copy()

        for layer in dag.serial_layers():
            subdag = layer['graph']

            for gate in subdag.twoQ_gates():
                physical_q0 = current_layout[gate.qargs[0]]
                physical_q1 = current_layout[gate.qargs[1]]
                if self.coupling_map.distance(physical_q0, physical_q1) != 1:
                    # Insert a new layer with the SWAP(s).
                    swap_layer = DAGCircuit()

                    path = self.coupling_map.shortest_undirected_path(physical_q0, physical_q1)
                    for swap in range(len(path) - 2):
                        connected_wire_1 = path[swap]
                        connected_wire_2 = path[swap + 1]

                        qubit_1 = current_layout[connected_wire_1]
                        qubit_2 = current_layout[connected_wire_2]

                        # create qregs
                        for qreg in current_layout.get_registers():
                            if qreg not in swap_layer.qregs.values():
                                swap_layer.add_qreg(qreg)

                        # create the swap operation
                        swap_layer.apply_operation_back(SwapGate(),
                                                        qargs=[qubit_1, qubit_2],
                                                        cargs=[])

                    # layer insertion
                    edge_map = current_layout.combine_into_edge_map(self.initial_layout)
                    new_dag.compose_back(swap_layer, edge_map)

                    # update current_layout
                    for swap in range(len(path) - 2):
                        current_layout.swap(path[swap], path[swap + 1])

            edge_map = current_layout.combine_into_edge_map(self.initial_layout)
            new_dag.extend_back(subdag, edge_map)

        return new_dag
def run ( self , dag ) : new_dag = DAGCircuit ( ) if self . initial_layout is None : if self . property_set [ "layout" ] : self . initial_layout = self . property_set [ "layout" ] else : self . initial_layout = Layout . generate_trivial_layout ( * dag . qregs . values ( ) ) if len ( dag . qubits ( ) ) != len ( self . initial_layout ) : raise TranspilerError ( 'The layout does not match the amount of qubits in the DAG' ) if len ( self . coupling_map . physical_qubits ) != len ( self . initial_layout ) : raise TranspilerError ( "Mappers require to have the layout to be the same size as the coupling map" ) current_layout = self . initial_layout . copy ( ) for layer in dag . serial_layers ( ) : subdag = layer [ 'graph' ] for gate in subdag . twoQ_gates ( ) : physical_q0 = current_layout [ gate . qargs [ 0 ] ] physical_q1 = current_layout [ gate . qargs [ 1 ] ] if self . coupling_map . distance ( physical_q0 , physical_q1 ) != 1 : # Insert a new layer with the SWAP(s). swap_layer = DAGCircuit ( ) path = self . coupling_map . shortest_undirected_path ( physical_q0 , physical_q1 ) for swap in range ( len ( path ) - 2 ) : connected_wire_1 = path [ swap ] connected_wire_2 = path [ swap + 1 ] qubit_1 = current_layout [ connected_wire_1 ] qubit_2 = current_layout [ connected_wire_2 ] # create qregs for qreg in current_layout . get_registers ( ) : if qreg not in swap_layer . qregs . values ( ) : swap_layer . add_qreg ( qreg ) # create the swap operation swap_layer . apply_operation_back ( SwapGate ( ) , qargs = [ qubit_1 , qubit_2 ] , cargs = [ ] ) # layer insertion edge_map = current_layout . combine_into_edge_map ( self . initial_layout ) new_dag . compose_back ( swap_layer , edge_map ) # update current_layout for swap in range ( len ( path ) - 2 ) : current_layout . swap ( path [ swap ] , path [ swap + 1 ] ) edge_map = current_layout . combine_into_edge_map ( self . initial_layout ) new_dag . extend_back ( subdag , edge_map ) return new_dag
Runs the BasicSwap pass on `dag`.
        Args:
            dag (DAGCircuit): DAG to map.

        Returns:
            DAGCircuit: A mapped DAG.

        Raises:
            TranspilerError: if the coupling map or the layout are not
            compatible with the DAG
Runs the BasicSwap pass on dag . Args : dag ( DAGCircuit ) : DAG to map .