Source code for qiskit.converters.circuit_to_dag

# This code is part of Qiskit.
# (C) Copyright IBM 2017, 2018.
# 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
# of this source tree or at
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
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"""Helper function for converting a circuit to a dag"""
import copy

from qiskit.dagcircuit.dagcircuit import DAGCircuit

[docs]def circuit_to_dag(circuit, copy_operations=True): """Build a ``DAGCircuit`` object from a ``QuantumCircuit``. Args: circuit (QuantumCircuit): the input circuit. copy_operations (bool): Deep copy the operation objects in the :class:`~.QuantumCircuit` for the output :class:`~.DAGCircuit`. This should only be set to ``False`` if the input :class:`~.QuantumCircuit` will not be used anymore as the operations in the output :class:`~.DAGCircuit` will be shared instances and modifications to operations in the :class:`~.DAGCircuit` will be reflected in the :class:`~.QuantumCircuit` (and vice versa). Return: DAGCircuit: the DAG representing the input circuit. Example: .. code-block:: from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit from qiskit.dagcircuit import DAGCircuit from qiskit.converters import circuit_to_dag q = QuantumRegister(3, 'q') c = ClassicalRegister(3, 'c') circ = QuantumCircuit(q, c) circ.h(q[0])[0], q[1]) circ.measure(q[0], c[0]) circ.rz(0.5, q[1]).c_if(c, 2) dag = circuit_to_dag(circ) """ dagcircuit = DAGCircuit() = dagcircuit.global_phase = circuit.global_phase dagcircuit.calibrations = circuit.calibrations dagcircuit.metadata = circuit.metadata dagcircuit.add_qubits(circuit.qubits) dagcircuit.add_clbits(circuit.clbits) for register in circuit.qregs: dagcircuit.add_qreg(register) for register in circuit.cregs: dagcircuit.add_creg(register) for instruction in op = instruction.operation if copy_operations: op = copy.deepcopy(op) dagcircuit.apply_operation_back(op, instruction.qubits, instruction.clbits) dagcircuit.duration = circuit.duration dagcircuit.unit = circuit.unit return dagcircuit