# Copyright 2022 D-Wave Systems Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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import dwave_networkx as dnx
[docs]def coupling_groups(hardware_graph):
"""Generate groups of couplers for which a limit on total coupling applies for each group.
Args:
hardware_graph (:class:`networkx.Graph`): The hardware graph of a QPU. Note that only
:term:`Zephyr` graphs have coupling groups.
Yields:
Lists of tuples, where each list is a group of couplers in ``hardware_graph``.
"""
if hardware_graph.graph.get('family') != 'zephyr':
return
relabel = dnx.zephyr_coordinates(hardware_graph.graph['rows']).linear_to_zephyr
for q in hardware_graph:
groups = [], []
U, W, K, J, Z = relabel(q)
for p in hardware_graph[q]:
u, w, k, j, z = relabel(p)
if U != u:
groups[2*Z+J+1-w].append((p, q))
elif J != j:
groups[Z+J-z].append((p, q))
else:
groups[(z-Z)//2].append((p, q))
yield from groups