module RGL::BidirectionalGraph

BGL defines the concept BidirectionalGraph as follows:

The BidirectionalGraph concept refines IncidenceGraph and adds the requirement for efficient access to the in-edges of each vertex. This concept is separated from IncidenceGraph because, for directed graphs, efficient access to in-edges typically requires more storage space, and many algorithms do not require access to in-edges. For undirected graphs, this is not an issue; because the in_edges() and out_edges() functions are the same, they both return the edges incident to the vertex.

Public Instance Methods

degree(v) click to toggle source

Returns the number of in-edges plus out-edges (for directed graphs) or the number of incident edges (for undirected graphs) of vertex v.

# File lib/rgl/bidirectional.rb, line 41
def degree(v)
  in_degree(v) + out_degree(v)
end
each_in_neighbor(v) { |u| ... } click to toggle source

Iterator providing access to the in-edges (for directed graphs) or incident edges (for undirected graphs) of vertex v. For both directed and undirected graphs, the target of an out-edge is required to be vertex v and the source is required to be a vertex that is adjacent to v.

# File lib/rgl/bidirectional.rb, line 24
def each_in_neighbor(v)
  raise NotImplementedError
  yield u
end
in_degree(v) click to toggle source

Returns the number of in-edges (for directed graphs) or the number of incident edges (for undirected graphs) of vertex v.

# File lib/rgl/bidirectional.rb, line 32
def in_degree(v)
  r = 0
  each_in_neighbor(v) { |u| r += 1 }
  r
end