# -*- coding: utf-8 -*-
# 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 http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""Helper function for converting a circuit to a dag"""
from qiskit.dagcircuit.dagcircuit import DAGCircuit
[docs]def circuit_to_dag(circuit):
"""Build a ``DAGCircuit`` object from a ``QuantumCircuit``.
Args:
circuit (QuantumCircuit): the input circuit.
Return:
DAGCircuit: the DAG representing the input circuit.
Example:
.. jupyter-execute::
from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
from qiskit.dagcircuit import DAGCircuit
from qiskit.converters import circuit_to_dag
from qiskit.visualization import dag_drawer
%matplotlib inline
q = QuantumRegister(3, 'q')
c = ClassicalRegister(3, 'c')
circ = QuantumCircuit(q, c)
circ.h(q[0])
circ.cx(q[0], q[1])
circ.measure(q[0], c[0])
circ.rz(0.5, q[1]).c_if(c, 2)
dag = circuit_to_dag(circ)
dag_drawer(dag)
"""
dagcircuit = DAGCircuit()
dagcircuit.name = circuit.name
for register in circuit.qregs:
dagcircuit.add_qreg(register)
for register in circuit.cregs:
dagcircuit.add_creg(register)
for instruction, qargs, cargs in circuit.data:
dagcircuit.apply_operation_back(instruction.copy(), qargs, cargs,
instruction.condition)
return dagcircuit