Developing Alternate Graph Types

This section is designed to guide developers who wish to write their own graph structures.

All LightGraphs functions rely on a standard API to function. As long as your graph structure is a subtype of AbstractGraph and implements the following API functions with the given return values, all functions within the LightGraphs package should just work:

• edges

• eltype

• has_edge

• has_vertex

• inneighbors

• is_directed: Note that since we use traits to determine directedness, is_directed for a CustomGraph type should have the following signatures:

  • is_directed(::Type{CustomGraph})::Bool
  • is_directed(g::CustomGraph)::Bool

• ne

• nv

• outneighbors

• vertices

If the graph structure is designed to represent weights on edges, the weights function should also be defined. Note that the output does not necessarily have to be a dense matrix, but it must be indexable via [u, v].