structure.info: Gaining information about graph structure
Description
Functions for exploring the basic structure of a network:
number of vertices and edges, the neighbors of a node, test whether
two vertices are connected by an edge.
Character string, specifying the type of neighboring
vertices to list in a directed graph. If out the vertices
to which an edge exist are listed, if in the
vertices from which an edge is dire
v1
The id of the first vertex. For directed graphs only edges
pointing from v1 to v2 are searched.
v2
The id of the second vertex. For directed graphs only edges
pointing from v1 to v2 are searched.
Value
vcount and ecount return integer
constants. neighbors returns an integer
vector. is.directed and are.connected return boolean
constants.
Details
These functions provide the basic structural information of a graph.
vcount gives the number of vertices in the graph.
ecount gives the number of edges in the graph.
neighbors gives the neighbors of a vertex. The vertices
connected by multiple edges are listed as many times as the number of
connecting edges.
is.directed gives whether the graph is directed or not. It just
gives its directed attribute.
are.connected decides whether there is an edge from v1
to v2.