Add universal methods (#241)

* Add universal methods

In the rust generated Python API we need to have fixed class inpurts to
satisfy the traits used by the pyo3 macro generated FFI functions. This
results in duplicate methods like digraph_dfs_edges and graph_dfs_edges
with the same implementation just differing input types. To simplify the
API for users this commit adds universal functions to the python side of
the retworkx package to take in any retworkx graph object and dispatch to
the proper function in the rust generated api that relies on strict
input types.

Fixes #215

* Add release notes

* Cleanup docs for new functions

* Add as_undirected flag to distance_matrix()

docs/source/api.rst

@@ -45,6 +45,9 @@ Random Circuit Functions
 Algorithm Functions
 -------------------
 
+Specific Graph Type Methods
+'''''''''''''''''''''''''''
+
 .. autosummary::
    :toctree: stubs
 
@@ -88,6 +91,27 @@ Algorithm Functions
    retworkx.digraph_find_cycle
    retworkx.digraph_union
 
+Universal Functions
+'''''''''''''''''''
+
+These functions are algorithm functions that wrap per graph object
+type functions in the algorithms API but can be run with a
+:class:`~retworkx.PyGraph`, :class:`~retworkx.PyDiGraph`, or
+:class:`~retworkx.PyDAG` object.
+
+.. autosummary::
+   :toctree: stubs
+
+   retworkx.distance_matrix
+   retworkx.floyd_warshall_numpy
+   retworkx.adjacency_matrix
+   retworkx.all_simple_paths
+   retworkx.astar_shortest_path
+   retworkx.dijkstra_shortest_paths
+   retworkx.dijkstra_shortest_path_lengths
+   retworkx.k_shortest_path_lengths
+   retworkx.dfs_edges
+
 Exceptions
 ----------
 

releasenotes/notes/add-universal-functions-1e54351f1f7afa4b.yaml

@@ -0,0 +1,16 @@
+---
+features:
+  - |
+    New universal functions that can take in a :class:`~retworkx.PyGraph` or
+    :class:`~retworkx.PyDiGraph` instead of being class specific have been to
+    the retworkx API. These new functions are:
+
+     * :func:`retworkx.distance_matrix`
+     * :func:`retworkx.floyd_warshall_numpy`
+     * :func:`retworkx.adjacency_matrix`
+     * :func:`retworkx.all_simple_paths`
+     * :func:`retworkx.astar_shortest_path`
+     * :func:`retworkx.dijkstra_shortest_paths`
+     * :func:`retworkx.dijkstra_shortest_path_lengths`
+     * :func:`retworkx.k_shortest_path_lengths`
+     * :func:`retworkx.dfs_edges`