Layered layout drawing algorithm

doc/reference/drawing.rst

@@ -95,4 +95,4 @@ Graph Layout
    spectral_layout
    spiral_layout
    multipartite_layout
-
+   layered_layout

doc/release/release_dev.rst

@@ -31,6 +31,9 @@ Improvements
 - [`#4640 <https://github.com/networkx/networkx/pull/4640>`_]
   ``prefix_tree`` now uses a non-recursive algorithm. The original recursive
   algorithm is still available via ``prefix_tree_recursive``.
+- [`#4743 <https://github.com/networkx/networkx/pull/4743>`_]
+  New ``layered_layout`` graph positioning algorithm for directed acyclic
+  graphs based on Sugiyama's method.
 
 API Changes
 -----------

examples/drawing/plot_layered_layout.py

@@ -0,0 +1,34 @@
+"""
+=================
+Layered layout
+=================
+
+This example presents `networkx.drawing.layered_layout` node positioning algorithm, and how its output can be used with `networkx.drawing.draw` to produce good looking graphs.
+"""
+import networkx as nx
+import matplotlib.pyplot as plt
+
+fig, axarr = plt.subplots(nrows=2, ncols=2, figsize=(8, 8))
+
+G1 = nx.gn_graph(20)
+
+pos, edges_path = nx.layered_layout(G1, align="vertical")
+nx.draw(G1, pos, edges_path=edges_path, ax=axarr[0][0])
+axarr[0][0].set_title("Growing Network graph, vertical")
+
+pos, edges_path = nx.layered_layout(G1, align="horizontal")
+nx.draw(G1, pos, edges_path=edges_path, ax=axarr[0][1])
+axarr[0][1].set_title("Growing Network graph, horizontal")
+
+G2 = nx.binomial_tree(4, create_using=nx.DiGraph)
+
+pos, edges_path = nx.layered_layout(G2, align="vertical")
+nx.draw(G2, pos, edges_path=edges_path, ax=axarr[1][0])
+axarr[1][0].set_title("Binomial tree graph, vertical")
+
+pos, edges_path = nx.layered_layout(G2, align="horizontal")
+nx.draw(G2, pos, edges_path=edges_path, ax=axarr[1][1])
+axarr[1][1].set_title("Binomial tree graph, horizontal")
+
+plt.tight_layout()
+plt.show()