diff options
| -rw-r--r-- | doc/reference/algorithms/planarity.rst | 1 | ||||
| -rw-r--r-- | networkx/algorithms/planarity.py | 46 |
2 files changed, 44 insertions, 3 deletions
diff --git a/doc/reference/algorithms/planarity.rst b/doc/reference/algorithms/planarity.rst index 95fe0b25..03ded5fa 100644 --- a/doc/reference/algorithms/planarity.rst +++ b/doc/reference/algorithms/planarity.rst @@ -7,4 +7,5 @@ Planarity :toctree: generated/ check_planarity + is_planar PlanarEmbedding diff --git a/networkx/algorithms/planarity.py b/networkx/algorithms/planarity.py index de94eecb..bc6ff2f0 100644 --- a/networkx/algorithms/planarity.py +++ b/networkx/algorithms/planarity.py @@ -1,7 +1,39 @@ from collections import defaultdict import networkx as nx -__all__ = ["check_planarity", "PlanarEmbedding"] +__all__ = ["check_planarity", "is_planar", "PlanarEmbedding"] + + +def is_planar(G): + """Returns True if and only if `G` is planar. + + A graph is *planar* iff it can be drawn in a plane without + any edge intersections. + + Parameters + ---------- + G : NetworkX graph + + Returns + ------- + bool + Whether the graph is planar. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2)]) + >>> nx.is_planar(G) + True + >>> nx.is_planar(nx.complete_graph(5)) + False + + See Also + -------- + check_planarity : + Check if graph is planar *and* return a `PlanarEmbedding` instance if True. + """ + + return check_planarity(G, counterexample=False)[0] def check_planarity(G, counterexample=False): @@ -49,6 +81,11 @@ def check_planarity(G, counterexample=False): A counterexample is only generated if the corresponding parameter is set, because the complexity of the counterexample generation is higher. + See also + -------- + is_planar : + Check for planarity without creating a `PlanarEmbedding` or counterexample. + References ---------- .. [1] Ulrik Brandes: @@ -777,9 +814,12 @@ class PlanarEmbedding(nx.DiGraph): See Also -------- + is_planar : + Preferred way to check if an existing graph is planar. + check_planarity : - Preferred way to check if an existing graph is planar. Also a more - convenient way to create a `PlanarEmbedding` from an existing graph. + A convenient way to create a `PlanarEmbedding`. If not planar, + it returns a subgraph that shows this. Examples -------- |