Glossary

dictionary

A Python dictionary maps keys to values. Also known as “hashes”, or “associative arrays” in other programming languages. See http://docs.python.org/tutorial/datastructures.html#dictionaries

edge

Edges are either two-tuples of nodes (u, v) or three tuples of nodes with an edge attribute dictionary (u, v, dict).

ebunch

An iteratable container of edge tuples like a list, iterator, or file.

edge attribute

Edges can have arbitrary Python objects assigned as attributes by using keyword/value pairs when adding an edge assigning to the G.edges[u][v] attribute dictionary for the specified edge u-v.

hashable

An object is hashable if it has a hash value which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() or __cmp__() method). Hashable objects which compare equal must have the same hash value.

Hashability makes an object usable as a dictionary key and a set member, because these data structures use the hash value internally.

All of Python’s immutable built-in objects are hashable, while no mutable containers (such as lists or dictionaries) are. Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id().

Definition from http://docs.python.org/glossary.html

nbunch

An nbunch is any iterable container of nodes that is not itself a node in the graph. It can be an iterable or an iterator, e.g. a list, set, graph, file, etc..

node

A node can be any hashable Python object except None.

node attribute

Nodes can have arbitrary Python objects assigned as attributes by using keyword/value pairs when adding a node or assigning to the G.nodes[n] attribute dictionary for the specified node n.