|
Data Structures and Algorithms
with Object-Oriented Design Patterns in Python |
In keeping with the design framework used throughout this text,
we view graphs as specialized containers.
Formally, the graph 
is an ordered pair
comprised of two sets--a set of vertices and a set of edges.
Informally, we can view a graph as a container with two compartments,
one which holds vertices and one which holds edges.
There are four kinds of objects--vertices, edges, undirected graphs, and directed graphs.
Accordingly, we define four abstract classes:
Vertex, Edge, Graph, and Digraph.
(See Figure 
).
Figure: Object class hierarchy
Copyright © 2003, 2004 by Bruno R. Preiss, P.Eng. All rights reserved.