AbstractGraph interface

AbstractEdge

An abstract type representing a single edge between two vertices of a graph.

AbstractEdgeIter

An abstract type representing an edge iterator.

AbstractGraph

An abstract type representing a graph.

NotImplementedError{M}(m)

Exception thrown when a method from the AbstractGraph interface is not implemented by a given graph type.

eltype(G)

Return the type of the graph's vertices (must be <: Integer)

reverse(e)

Create a new edge from e with source and destination vertices reversed.

Examples

julia> using Graphs

julia> g = SimpleDiGraph(2);

julia> add_edge!(g, 1, 2);

julia> reverse(first(edges(g)))
Edge 2 => 1

zero(G)

Return a zero-vertex, zero-edge version of the graph type G. The fallback is defined for graph values zero(g::G) = zero(G).

Examples

julia> using Graphs

julia> g = SimpleDiGraph([0 1 0 0 0; 0 0 1 0 0; 1 0 0 1 0; 0 0 0 0 1; 0 0 0 1 0]);

julia> zero(typeof(g))
{0, 0} directed simple Int64 graph

julia> zero(g)
{0, 0} directed simple Int64 graph

dst(e)

Return the destination vertex of edge e.

Examples

julia> using Graphs

julia> g = SimpleGraph(2);

julia> add_edge!(g, 1, 2);

julia> dst(first(edges(g)))
2

edges(g)

Return (an iterator to or collection of) the edges of a graph. For AbstractSimpleGraphs it returns a SimpleEdgeIter. The expressions e in edges(g) and e ∈ edges(g) evaluate as calls to has_edge.

Implementation Notes

A returned iterator is valid for one pass over the edges, and is invalidated by changes to g.

Examples

julia> using Graphs

julia> g = path_graph(3);

julia> collect(edges(g))
2-element Vector{Graphs.SimpleGraphs.SimpleEdge{Int64}}:
 Edge 1 => 2
 Edge 2 => 3

edgetype(g)

Return the type of graph g's edge

has_edge(g, s, d)

Return true if the graph g has an edge from node s to node d.

An optional has_edge(g, e) can be implemented to check if an edge belongs to a graph, including any data other than source and destination node.

e in edges(g) or e ∈ edges(g) evaluate as calls to has_edge, c.f. edges.

Examples

julia> using Graphs

julia> g = SimpleDiGraph(2);

julia> add_edge!(g, 1, 2);

julia> has_edge(g, 1, 2)
true

julia> has_edge(g, 2, 1)
false

has_vertex(g, v)

Return true if v is a vertex of g.

Examples

julia> using Graphs

julia> has_vertex(SimpleGraph(2), 1)
true

julia> has_vertex(SimpleGraph(2), 3)
false

inneighbors(g, v)

Return a list of all neighbors connected to vertex v by an incoming edge.

Implementation Notes

Returns a reference to the current graph's internal structures, not a copy. Do not modify result. If the graph is modified, the behavior is undefined: the array behind this reference may be modified too, but this is not guaranteed.

Examples

julia> using Graphs

julia> g = SimpleDiGraph([0 1 0 0 0; 0 0 1 0 0; 1 0 0 1 0; 0 0 0 0 1; 0 0 0 1 0]);

julia> inneighbors(g, 4)
2-element Vector{Int64}:
 3
 5

is_directed(G)

Return true if the graph type G is a directed graph; false otherwise. New graph types must implement is_directed(::Type{<:G}). The method can also be called with is_directed(g::G)

Examples

julia> using Graphs

julia> is_directed(SimpleGraph(2))
false

julia> is_directed(SimpleGraph)
false

julia> is_directed(SimpleDiGraph(2))
true

ne(g)

Return the number of edges in g.

Examples

julia> using Graphs

julia> g = path_graph(3);

julia> ne(g)
2

nv(g)

Return the number of vertices in g.

Examples

julia> using Graphs

julia> nv(SimpleGraph(3))
3

outneighbors(g, v)

Return a list of all neighbors connected to vertex v by an outgoing edge.

Implementation Notes

Returns a reference to the current graph's internal structures, not a copy. Do not modify result. If the graph is modified, the behavior is undefined: the array behind this reference may be modified too, but this is not guaranteed.

Examples

julia> using Graphs

julia> g = SimpleDiGraph([0 1 0 0 0; 0 0 1 0 0; 1 0 0 1 0; 0 0 0 0 1; 0 0 0 1 0]);

julia> outneighbors(g, 4)
1-element Vector{Int64}:
 5

src(e)

Return the source vertex of edge e.

Examples

julia> using Graphs

julia> g = SimpleGraph(2);

julia> add_edge!(g, 1, 2);

julia> src(first(edges(g)))
1

vertices(g)

Return (an iterator to or collection of) the vertices of a graph.

Implementation Notes

A returned iterator is valid for one pass over the vertices, and is invalidated by changes to g.

Examples

julia> using Graphs

julia> collect(vertices(SimpleGraph(4)))
4-element Vector{Int64}:
 1
 2
 3
 4

zero(G)

Return a zero-vertex, zero-edge version of the graph type G. The fallback is defined for graph values zero(g::G) = zero(G).

Examples

julia> using Graphs

julia> g = SimpleDiGraph([0 1 0 0 0; 0 0 1 0 0; 1 0 0 1 0; 0 0 0 0 1; 0 0 0 1 0]);

julia> zero(typeof(g))
{0, 0} directed simple Int64 graph

julia> zero(g)
{0, 0} directed simple Int64 graph