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Source code for qiskit.transpiler.passes.layout.trivial_layout

# 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.

"""Choose a Layout by assigning ``n`` circuit qubits to device qubits ``0, .., n-1``."""

from qiskit.transpiler.layout import Layout
from qiskit.transpiler.basepasses import AnalysisPass
from qiskit.transpiler.exceptions import TranspilerError


[docs]class TrivialLayout(AnalysisPass): """Choose a Layout by assigning ``n`` circuit qubits to device qubits ``0, .., n-1``. A pass for choosing a Layout of a circuit onto a Coupling graph, using a simple round-robin order. This pass associates a physical qubit (int) to each virtual qubit of the circuit (Qubit) in increasing order. Does not assume any ancilla. """ def __init__(self, coupling_map): """TrivialLayout initializer. Args: coupling_map (Coupling): directed graph representing a coupling map. Raises: TranspilerError: if invalid options """ super().__init__() self.coupling_map = coupling_map
[docs] def run(self, dag): """Run the TrivialLayout pass on `dag`. Args: dag (DAGCircuit): DAG to find layout for. Raises: TranspilerError: if dag wider than self.coupling_map """ if dag.num_qubits() > self.coupling_map.size(): raise TranspilerError("Number of qubits greater than device.") self.property_set["layout"] = Layout.generate_trivial_layout( *(dag.qubits + list(dag.qregs.values())) )