def _minimum_spanning_tree_subgraph(G):
mst_subgraph = Graph()
if type(G) is not Graph:
raise Exception("input graph must be undirected")
mst_df = minimum_spanning_tree_wrapper.minimum_spanning_tree(G)
if G.renumbered:
mst_df = G.unrenumber(mst_df, "src")
mst_df = G.unrenumber(mst_df, "dst")
mst_subgraph.from_cudf_edgelist(
mst_df, source="src", destination="dst", edge_attr="weight"
)
return mst_subgraph
def _maximum_spanning_tree_subgraph(G):
mst_subgraph = Graph()
if type(G) is not Graph:
raise Exception("input graph must be undirected")
if G.adjlist.weights is not None:
G.adjlist.weights = G.adjlist.weights.mul(-1)
mst_df = minimum_spanning_tree_wrapper.minimum_spanning_tree(G)
# revert to original weights
if G.adjlist.weights is not None:
G.adjlist.weights = G.adjlist.weights.mul(-1)
mst_df["weight"] = mst_df["weight"].mul(-1)
if G.renumbered:
mst_df = G.unrenumber(mst_df, "src")
mst_df = G.unrenumber(mst_df, "dst")
mst_subgraph.from_cudf_edgelist(
mst_df, source="src", destination="dst", edge_attr="weight"
)
return mst_subgraph