Quellcode für qiskit.pulse.transforms.dag

# This code is part of Qiskit.
# (C) Copyright IBM 2021.
# 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.
"""A collection of functions to convert ScheduleBlock to DAG representation."""

import rustworkx as rx

from qiskit.pulse.exceptions import UnassignedReferenceError

[Doku]def block_to_dag(block) -> rx.PyDAG: """Convert schedule block instruction into DAG. ``ScheduleBlock`` can be represented as a DAG as needed. For example, equality of two programs are efficiently checked on DAG representation. .. code-block:: python with pulse.build() as sched1: with pulse.align_left(): pulse.play(my_gaussian0, pulse.DriveChannel(0)) pulse.shift_phase(1.57, pulse.DriveChannel(2)) pulse.play(my_gaussian1, pulse.DriveChannel(1)) with pulse.build() as sched2: with pulse.align_left(): pulse.shift_phase(1.57, pulse.DriveChannel(2)) pulse.play(my_gaussian1, pulse.DriveChannel(1)) pulse.play(my_gaussian0, pulse.DriveChannel(0)) Here the ``sched1 `` and ``sched2`` are different implementations of the same program, but it is difficult to confirm on the list representation. Another example is instruction optimization. .. code-block:: python with pulse.build() as sched: with pulse.align_left(): pulse.shift_phase(1.57, pulse.DriveChannel(1)) pulse.play(my_gaussian0, pulse.DriveChannel(0)) pulse.shift_phase(-1.57, pulse.DriveChannel(1)) In above program two ``shift_phase`` instructions can be cancelled out because they are consecutive on the same drive channel. This can be easily found on the DAG representation. Args: block ("ScheduleBlock"): A schedule block to be converted. Returns: Instructions in DAG representation. Raises: PulseError: When the context is invalid subclass. """ if block.alignment_context.is_sequential: return _sequential_allocation(block) return _parallel_allocation(block)
def _sequential_allocation(block) -> rx.PyDAG: """A helper function to create a DAG of a sequential alignment context.""" dag = rx.PyDAG() edges = [] prev_id = None for elm in block.blocks: node_id = dag.add_node(elm) if dag.num_nodes() > 1: edges.append((prev_id, node_id)) prev_id = node_id dag.add_edges_from_no_data(edges) return dag def _parallel_allocation(block) -> rx.PyDAG: """A helper function to create a DAG of a parallel alignment context.""" dag = rx.PyDAG() slots = {} edges = set() prev_reference = None for elm in block.blocks: node_id = dag.add_node(elm) try: for chan in elm.channels: prev_id = slots.pop(chan, prev_reference) if prev_id is not None: edges.add((prev_id, node_id)) slots[chan] = node_id except UnassignedReferenceError: # Broadcasting channels because the reference's channels are unknown. for chan, prev_id in slots.copy().items(): edges.add((prev_id, node_id)) slots[chan] = node_id prev_reference = node_id dag.add_edges_from_no_data(list(edges)) return dag