Core Functions
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LightGraphs.jl includes the following core functions:
Full Docs
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LightGraphs.add_vertices! — Method
add_vertices!(g, n)Add n new vertices to the graph g. Return the number of vertices that were added successfully.
Examples
julia> using LightGraphs
julia> g = SimpleGraph()
{0, 0} undirected simple Int64 graph
julia> add_vertices!(g, 2)
2#
LightGraphs.all_neighbors — Function
all_neighbors(g, v)Return a list of all inbound and outbound neighbors of v in g. For undirected graphs, this is equivalent to both outneighbors and inneighbors.
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 LightGraphs
julia> g = DiGraph(3);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 1);
julia> all_neighbors(g, 1) 1-element Array{Int64,1}: 3
julia> all_neighbors(g, 2) 1-element Array{Int64,1}: 3
julia> all_neighbors(g, 3) 2-element Array{Int64,1}: 1 2#
LightGraphs.common_neighbors — Method
common_neighbors(g, u, v)Return the neighbors common to vertices u and v in g.
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 LightGraphs
julia> g = SimpleGraph(4);
julia> add_edge!(g, 1, 2);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 4);
julia> add_edge!(g, 4, 1);
julia> add_edge!(g, 1, 3);
julia> common_neighbors(g, 1, 3)
2-element Array{Int64,1}:
2
4
julia> common_neighbors(g, 1, 4)
1-element Array{Int64,1}:
3#
LightGraphs.degree — Function
degree(g[, v])Return a vector corresponding to the number of edges which start or end at each vertex in graph g. If v is specified, only return degrees for vertices in v. For directed graphs, this value equals the incoming plus outgoing edges. For undirected graphs, it equals the connected edges.
Examples
julia> using LightGraphs
julia> g = DiGraph(3);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 1);
julia> degree(g)
3-element Array{Int64,1}:
1
1
2#
LightGraphs.density — Function
density(g)Return the density of g. Density is defined as the ratio of the number of actual edges to the number of possible edges ( for directed graphs and for undirected graphs).
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LightGraphs.has_self_loops — Method
has_self_loops(g)Return true if g has any self loops.
Examples
julia> using LightGraphs
julia> g = SimpleGraph(2);
julia> add_edge!(g, 1, 2);
julia> has_self_loops(g)
false
julia> add_edge!(g, 1, 1);
julia> has_self_loops(g)
true#
LightGraphs.indegree — Method
indegree(g[, v])Return a vector corresponding to the number of edges which end at each vertex in graph g. If v is specified, only return degrees for vertices in v.
Examples
julia> using LightGraphs
julia> g = DiGraph(3);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 1);
julia> indegree(g)
3-element Array{Int64,1}:
1
0
1#
LightGraphs.is_ordered — Method
is_ordered(e)Return true if the source vertex of edge e is less than or equal to the destination vertex.
Examples
julia> using LightGraphs
julia> g = DiGraph(2);
julia> add_edge!(g, 2, 1);
julia> is_ordered(first(edges(g)))
false#
LightGraphs.neighbors — Method
neighbors(g, v)Return a list of all neighbors reachable from vertex v in g. For directed graphs, the default is equivalent to outneighbors; use all_neighbors to list inbound and outbound neighbors.
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 LightGraphs
julia> g = DiGraph(3);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 1);
julia> neighbors(g, 1)
0-element Array{Int64,1}
julia> neighbors(g, 2)
1-element Array{Int64,1}:
3
julia> neighbors(g, 3)
1-element Array{Int64,1}:
1#
LightGraphs.num_self_loops — Method
num_self_loops(g)Return the number of self loops in g.
Examples
julia> using LightGraphs
julia> g = SimpleGraph(2);
julia> add_edge!(g, 1, 2);
julia> num_self_loops(g)
0
julia> add_edge!(g, 1, 1);
julia> num_self_loops(g)
1#
LightGraphs.outdegree — Method
outdegree(g[, v])Return a vector corresponding to the number of edges which start at each vertex in graph g. If v is specified, only return degrees for vertices in v.
Examples
julia> using LightGraphs
julia> g = DiGraph(3);
julia> add_edge!(g, 2, 3);
julia> add_edge!(g, 3, 1);
julia> outdegree(g)
3-element Array{Int64,1}:
0
1
1#
LightGraphs.squash — Method
squash(g)Return a copy of a graph with the smallest practical type that can accommodate all vertices.
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LightGraphs.weights — Method
weights(g)Return the weights of the edges of a graph g as a matrix. Defaults to LightGraphs.DefaultDistance.
Implementation Notes
In general, referencing the weight of a nonexistent edge is undefined behavior. Do not rely on the weights matrix as a substitute for the graph’s adjacency_matrix.