Add Left-Right Planarity test. (#475)

* Add Left-Right Planarity test. This commit implements a new function `is_planar` that checks if an undirected graph can be drawn in a plane without any edge intersections. The planarity check algorithm is based on the Left-Right Planarity Test. Reference: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.217.9208 * fix clippy * fix compiler error * add generalized Petersen graph as test cases * remove old release note * Update release note import * fix release note * `or_insert` can be omitted. * cargo fmt Co-authored-by: Matthew Treinish <mtreinish@kortar.org> Co-authored-by: Ivan Carvalho <8753214+IvanIsCoding@users.noreply.github.com>
Qiskit · Sep 29, 2022 · 5b50f3f · 5b50f3f
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diff --git a/docs/source/api.rst b/docs/source/api.rst
@@ -182,6 +182,7 @@ Other Algorithm Functions
    rustworkx.core_number
    rustworkx.graph_greedy_color
    rustworkx.metric_closure
+   rustworkx.is_planar
 
 .. _generator_funcs:
 

diff --git a/releasenotes/notes/is-planar-58bb8604ae00f1a1.yaml b/releasenotes/notes/is-planar-58bb8604ae00f1a1.yaml
@@ -0,0 +1,12 @@
+---
+features:
+  - |
+    Implements a new function :func:`~rustworkx.is_planar` that
+    checks whether an undirected :class:`~rustworkx.PyGraph` is planar.
+
+    .. jupyter-execute::
+
+      import rustworkx as rx
+
+      graph = rx.generators.mesh_graph(5)
+      print('Is K_5 graph planar?', rx.is_planar(graph))
diff --git a/rustworkx-core/src/lib.rs b/rustworkx-core/src/lib.rs
@@ -73,6 +73,7 @@ pub mod centrality;
 pub mod connectivity;
 /// Module for maximum weight matching algorithms.
 pub mod max_weight_matching;
+pub mod planar;
 pub mod shortest_path;
 pub mod traversal;
 // These modules define additional data structures