Base edge representation.

Edges have five properties:

• start, which is the starting node
  
• end, which is the end node
  
• is_directed, which indicates if the edge is
  directed or undirected
  
• name, which is a unique, non-None value optionally
  passed in at instantiation time, and used for hashing
  comparisons
  
• data, which is a dictionary of all non-private
  (ie, user-defined) attributes of this node

Properties

def start(self):

    Returns the starting point for this edge.

def end(self):

    Returns the ending point for this edge.

def is_directed(self):

    Returns whether this is a directed edge or not.

Constructors

def __init__(self, start, end, name=None, is_directed=True, **kwargs):

 Initializes the Edge.

 Accepts start and end arguments, which should be Node objects,  
 an optional name (one will be autogenerated based on object id  
 if not provided), the is_directed flag, which controls whether  
 this is a directed or undirected edge, and a variable number of  
 kwargs, which will be mapped into attributes.

 Usage:  

 >>> e = Edge(Node("A"), Node("B"), "AB", is_directed=False, weight=5)
 >>> e.name  
 "AB"  
 >>> e.start  
 Node(name=A)  
 >>> e.end  
 Node(name=B)  
 >>> e.weight  
 5

Functions

def other_end(self, starting_point):

 Returns the other end of the edge from the given point.

 If the point given is not an endpoint on this edge or the   
 endpoint on a directed edge, this raises AttributeError.