# 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 dag to a circuit."""
import copy
from qiskit.circuit import QuantumCircuit, CircuitInstruction
[documentos]def dag_to_circuit(dag, copy_operations=True):
"""Build a ``QuantumCircuit`` object from a ``DAGCircuit``.
Args:
dag (DAGCircuit): the input dag.
copy_operations (bool): Deep copy the operation objects
in the :class:`~.DAGCircuit` for the output :class:`~.QuantumCircuit`.
This should only be set to ``False`` if the input :class:`~.DAGCircuit`
will not be used anymore as the operations in the output
:class:`~.QuantumCircuit` will be shared instances and
modifications to operations in the :class:`~.DAGCircuit` will
be reflected in the :class:`~.QuantumCircuit` (and vice versa).
Return:
QuantumCircuit: the circuit representing the input dag.
Example:
.. plot::
:include-source:
from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
from qiskit.dagcircuit import DAGCircuit
from qiskit.converters import circuit_to_dag
from qiskit.circuit.library.standard_gates import CHGate, U2Gate, CXGate
from qiskit.converters import dag_to_circuit
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)
circuit = dag_to_circuit(dag)
circuit.draw('mpl')
"""
name = dag.name or None
circuit = QuantumCircuit(
dag.qubits,
dag.clbits,
*dag.qregs.values(),
*dag.cregs.values(),
name=name,
global_phase=dag.global_phase,
)
circuit.metadata = dag.metadata
circuit.calibrations = dag.calibrations
for node in dag.topological_op_nodes():
op = node.op
if copy_operations:
op = copy.deepcopy(op)
circuit._append(CircuitInstruction(op, node.qargs, node.cargs))
circuit.duration = dag.duration
circuit.unit = dag.unit
return circuit