Source code for qiskit.converters.circuit_to_instruction

# This code is part of Qiskit.
# (C) Copyright IBM 2017, 2019.
# 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
# that they have been altered from the originals.

"""Helper function for converting a circuit to an instruction."""

from qiskit.exceptions import QiskitError
from qiskit.circuit.instruction import Instruction
from qiskit.circuit.quantumregister import QuantumRegister
from qiskit.circuit.classicalregister import ClassicalRegister, Clbit

[docs]def circuit_to_instruction(circuit, parameter_map=None, equivalence_library=None, label=None): """Build an :class:`~.circuit.Instruction` object from a :class:`.QuantumCircuit`. The instruction is anonymous (not tied to a named quantum register), and so can be inserted into another circuit. The instruction will have the same string name as the circuit. Args: circuit (QuantumCircuit): the input circuit. parameter_map (dict): For parameterized circuits, a mapping from parameters in the circuit to parameters to be used in the instruction. If None, existing circuit parameters will also parameterize the instruction. equivalence_library (EquivalenceLibrary): Optional equivalence library where the converted instruction will be registered. label (str): Optional instruction label. Raises: QiskitError: if parameter_map is not compatible with circuit Return: qiskit.circuit.Instruction: an instruction equivalent to the action of the input circuit. Upon decomposition, this instruction will yield the components comprising the original circuit. Example: .. code-block:: from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit from qiskit.converters import circuit_to_instruction 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) circuit_to_instruction(circ) """ # pylint: disable=cyclic-import from qiskit.circuit.quantumcircuit import QuantumCircuit if parameter_map is None: parameter_dict = {p: p for p in circuit.parameters} else: parameter_dict = circuit._unroll_param_dict(parameter_map) if parameter_dict.keys() != circuit.parameters: raise QiskitError( ( "parameter_map should map all circuit parameters. " "Circuit parameters: {}, parameter_map: {}" ).format(circuit.parameters, parameter_dict) ) out_instruction = Instruction(, num_qubits=circuit.num_qubits, num_clbits=circuit.num_clbits, params=[*parameter_dict.values()], label=label, ) out_instruction.condition = None target = circuit.assign_parameters(parameter_dict, inplace=False) if equivalence_library is not None: equivalence_library.add_equivalence(out_instruction, target) regs = [] if out_instruction.num_qubits > 0: q = QuantumRegister(out_instruction.num_qubits, "q") regs.append(q) if out_instruction.num_clbits > 0: c = ClassicalRegister(out_instruction.num_clbits, "c") regs.append(c) qubit_map = {bit: q[idx] for idx, bit in enumerate(circuit.qubits)} clbit_map = {bit: c[idx] for idx, bit in enumerate(circuit.clbits)} definition = [ instruction.replace( qubits=[qubit_map[y] for y in instruction.qubits], clbits=[clbit_map[y] for y in instruction.clbits], ) for instruction in ] # fix condition for rule in definition: condition = getattr(rule.operation, "condition", None) if condition: reg, val = condition if isinstance(reg, Clbit): rule.operation.condition = (clbit_map[reg], val) elif reg.size == c.size: rule.operation.condition = (c, val) else: raise QiskitError( "Cannot convert condition in circuit with " "multiple classical registers to instruction" ) qc = QuantumCircuit(*regs, for instruction in definition: qc._append(instruction) if circuit.global_phase: qc.global_phase = circuit.global_phase out_instruction.definition = qc return out_instruction