DrawSimpleGraphs
Drawing functions for SimpleGraphs
.
Given a SimpleGraph
, the function draw(G)
draws G
in its current embedding.
If the graph does not have an embedding, then it is given a circular embedding.
If further operations on the drawing are desired,
then Plots
or SimpleDrawing
functions may be used.
julia> using SimpleGraphs, DrawSimpleGraphs, Plots
julia> G = Cube(4)
Cube graph Q(4) (n=16, m=32)
julia> embed(G,:combined)
julia> draw(G)
julia> savefig("fourcube.png")
Embedding Commands
The following functions reside in SimpleGraphs
. They are used to
create and manipulate embeddings associated with a graph.
Create an embedding
embed(G,method)
creates a new embedding of G
. The second
argument method is a symbol associated with an embedding algorithm.
The method
can be one of the following:
:circular
(default) arranges the vertices in a circle.:random
arranges the vertices at random.:spring
arranges the vertices by modeling edges as springs holding repelling vertices together.:stress
arranges the vertices by attempting to put vertices geometric distance equal to their graphtheoretic distance.:combined
is equivalent to first performing aspring
embedding followed by astress
embedding. Often gives nice results.:spectral
arranges the vertices based on the eigenvectors of the Laplacian matrix of the graph. Specifically, thex
coordinates come from the eigenvector associated with the second smallest eigenvalue, and they
coordinates come from the eigenvector associated with the third smallest.
In addition, embed(G,xy)
will give the graph an embedding
specified in the dictionary xy
where maps vertices to twoelement
vectors.
Modify an embedding

has_embedding(G)
checks to see if the graph has been provided with an embedding. 
getxy(G)
retrieves a copy of the embedding. Modifying the output ofgetxy
does not modify the embedding of the graph. 
set_line_color(G,name)
assigns the color in the stringname
to the edges and boundaries of the vertices. Defaults to"black"
. 
get_line_color(G)
returns the line color. 
set_fill_color(G,name)
assigns the color in the stringname
to be the fill color of the vertices. Defaults to"white"
. 
set_vertex_size(G,sz)
sets the size of the drawn vertices to the integersz
. 
get_vertex_size(G)
returns the size of the vertices. 
transform(G,A,b)
applies an affine transformation to all coordinates in the graph's drawing. HereA
is 2by2 matrix andb
is a 2vector. Each pointp
is mapped toA*p+b
. Special versions of this command are provided byscale
,rotate
,translate
, andrecenter
. (Note: Some of these function names cause collisions, so I may change them.) 
edge_length(G,uv)
returns the geometric length of the edgeuv
. Note this fails ifG
does not have an embedding.edge_length(G)
returns an array of the edge lengths.
Vertex Labels
Use draw_labels(G)
after draw(G)
to insert vertex names into the drawing.
Optionally, add a font size, draw_labels(G,sz)
, to make the labels small
enough to fit (or use set_vertex_size
to make larger vertices).
julia> G = Cube(3)
Cube graph Q(3) (n=8, m=12)
julia> embed(G,:combined)
julia> set_vertex_size(G,20)
julia> draw(G)
julia> draw_labels(G)
Example: Knight's Tour
The function KnightTourDrawing(r,c)
to solve the problem
of finding a knight's tour on an r
byc
chess board and
drawing the solution.
julia> KnightTourDrawing(8,8)
Searching for a Hamiltonian cycle in an 8by8 Knight's move graph
1374.144891 seconds (9.02 G allocations: 1002.489 GiB, 12.68% gc time)
Finished