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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/algorithms/isolate.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/algorithms/isolate.py | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/isolate.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/isolate.py new file mode 100644 index 00000000..1ea8abe9 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/isolate.py @@ -0,0 +1,107 @@ +""" +Functions for identifying isolate (degree zero) nodes. +""" + +import networkx as nx + +__all__ = ["is_isolate", "isolates", "number_of_isolates"] + + +@nx._dispatchable +def is_isolate(G, n): + """Determines whether a node is an isolate. + + An *isolate* is a node with no neighbors (that is, with degree + zero). For directed graphs, this means no in-neighbors and no + out-neighbors. + + Parameters + ---------- + G : NetworkX graph + + n : node + A node in `G`. + + Returns + ------- + is_isolate : bool + True if and only if `n` has no neighbors. + + Examples + -------- + >>> G = nx.Graph() + >>> G.add_edge(1, 2) + >>> G.add_node(3) + >>> nx.is_isolate(G, 2) + False + >>> nx.is_isolate(G, 3) + True + """ + return G.degree(n) == 0 + + +@nx._dispatchable +def isolates(G): + """Iterator over isolates in the graph. + + An *isolate* is a node with no neighbors (that is, with degree + zero). For directed graphs, this means no in-neighbors and no + out-neighbors. + + Parameters + ---------- + G : NetworkX graph + + Returns + ------- + iterator + An iterator over the isolates of `G`. + + Examples + -------- + To get a list of all isolates of a graph, use the :class:`list` + constructor:: + + >>> G = nx.Graph() + >>> G.add_edge(1, 2) + >>> G.add_node(3) + >>> list(nx.isolates(G)) + [3] + + To remove all isolates in the graph, first create a list of the + isolates, then use :meth:`Graph.remove_nodes_from`:: + + >>> G.remove_nodes_from(list(nx.isolates(G))) + >>> list(G) + [1, 2] + + For digraphs, isolates have zero in-degree and zero out_degre:: + + >>> G = nx.DiGraph([(0, 1), (1, 2)]) + >>> G.add_node(3) + >>> list(nx.isolates(G)) + [3] + + """ + return (n for n, d in G.degree() if d == 0) + + +@nx._dispatchable +def number_of_isolates(G): + """Returns the number of isolates in the graph. + + An *isolate* is a node with no neighbors (that is, with degree + zero). For directed graphs, this means no in-neighbors and no + out-neighbors. + + Parameters + ---------- + G : NetworkX graph + + Returns + ------- + int + The number of degree zero nodes in the graph `G`. + + """ + return sum(1 for v in isolates(G)) |