def to_subgraphs(graph: nx.Graph, samples: list) -> list:
"""Converts a list of samples to a list of subgraphs.
Given a list of samples, with each sample of ``len(nodes)`` being a list of zeros and ones,
this function returns a list of subgraphs selected by, for each sample, picking the nodes
corresponding to ones and creating the induced subgraph. The subgraph is specified as a list
of selected nodes. For example, given an input 6-node graph, a sample :math:`[0, 1, 1, 0, 0,
1]` is converted to a subgraph :math:`[1, 2, 5]`.
Args:
graph (nx.Graph): the input graph
samples (list): a list of samples, each a binary sequence of ``len(nodes)``
Returns:
list[list[int]]: a list of subgraphs, where each subgraph is represented by a list of its
nodes
"""
graph_nodes = list(graph.nodes)
node_number = len(graph_nodes)
subgraph_samples = [sample.modes_from_counts(s) for s in samples]
if graph_nodes != list(range(node_number)):
return [sorted([graph_nodes[i] for i in s]) for s in subgraph_samples]
return subgraph_samples
def test_modes_from_counts():
"""Test if the function ``strawberryfields.gbs.sample.modes_from_counts`` returns the correct
mode samples when input a set of photon count samples."""
counts = [[0, 0, 0, 0], [1.0, 0.0, 0.0, 2.0], [1, 1, 1, 0], [1, 2, 1, 0], [0, 1, 0, 2, 4]]
modes = [[], [0, 3, 3], [0, 1, 2], [0, 1, 1, 2], [1, 3, 3, 4, 4, 4, 4]]
assert [sample.modes_from_counts(s) for s in counts] == modes