def amr_subgraphs_optimized(g, n_min=1, n_max=None): # g: AMRGraph object
""" -> connected subgraphs whose number of nodes is >= n_min & <= n_max """
output = defaultdict(list)
# PROXY_AFP_ENG_20021112_0467.11 - a cyclic graph
if not nx.is_directed_acyclic_graph(g):
print('The input graph is not directed acyclic.')
return output
amr_root = list(g.successors('@'))[0]
order = list(nx.dfs_preorder_nodes(g, amr_root))
# print(order)
if not n_max:
n_max = len(g.nodes())
# assumption: n_min < n_max
for i in range(n_min, n_max + 1):
# print(i)
for n in order:
# pool = list(nx.dfs_preorder_nodes(g,'s',depth_limit=i-1))
pool = set(y for v in nx.dfs_successors(g, n, depth_limit=i -
1).values() for y in v)
# print(n,pool)
if len(pool) < i - 1:
continue
for ns in itertools.combinations(pool, i - 1):
sg = g.subgraph((n, ) + ns).copy()
if nx.is_connected(sg.to_undirected()):
amr_root = list(nx.topological_sort(sg))[0]
sg.add_edge('@', amr_root, label='')
sg = AMRGraph(sg)
sg.meta = '# connected subgraph of {} nodes'.format(i)
output[i].append(sg)
return output
def construct_amr_subgraph(g, nodes, root_node=None):
""" Add dummy root node '@', apply AMRGraph type """
if root_node:
output = g.subgraph(nodes.union({root_node})).copy()
else:
output = g.subgraph(nodes).copy()
# assumption: nx.is_directed_acyclic_graph(output)==True
root_node = list(nx.topological_sort(output))[0]
output.add_edge('@', root_node, label='')
output = AMRGraph(output)
output.meta = '# root node: {}'.format(root_node)
return output
def amr_subgraphs(g, num): # g: AMRGraph object
""" -> connected subgraphs with more than num nodes """
output = defaultdict(list)
# assumption: num < len(g.nodes())+1
for i in range(num, len(g.nodes()) + 1):
for nodes in itertools.combinations(g.nodes(), i):
sg = g.subgraph(nodes).copy()
if nx.is_connected(sg.to_undirected()) and '@' not in sg.nodes():
amr_root = list(nx.topological_sort(sg))[0]
sg.add_edge('@', amr_root, label='')
sg = AMRGraph(sg)
sg.meta = '# connected subgraph of {} nodes'.format(i)
output[i].append(sg)
return output
