Draw a graph of matrices in LaTeX using Sage

18 octobre 2012 | Catégories: latex, sage | View Comments

In version 5.3 of Sage, if the vertices of a graph are matrices, then the default latex output does not compile. The default format is a tikzpicture and uses the tkz-berge library. One solution is to change the format to dot2tex. See below.

The default tikz output is:

sage: m = matrix(3, range(9))
sage: m.set_immutable()
sage: G = Graph()
sage: G.add_vertex(m)
sage: latex(G)
\begin{tikzpicture}
%
\useasboundingbox (0,0) rectangle (5.0cm,5.0cm);
%
\definecolor{cv0}{rgb}{0.0,0.0,0.0}
\definecolor{cfv0}{rgb}{1.0,1.0,1.0}
\definecolor{clv0}{rgb}{0.0,0.0,0.0}
%
\Vertex[style={minimum size=1.0cm,draw=cv0,fill=cfv0,text=clv0,shape=circle},
LabelOut=false,L=\hbox{$\left(\begin{array}{rrr}
0 & 1 & 2 \\
3 & 4 & 5 \\
6 & 7 & 8
\end{array}\right)$},x=2.5cm,y=2.5cm]{v0}
%
%
\end{tikzpicture}

This output does not compile. Here is the error I get:

sage: view(G)
An error occurred.
This is pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009) (format=pdflatex 2011.4.19)  18 OCT
2012 21:34
entering extended mode

[...]

! Use of \tikz@@scope@env doesn't match its definition.
\pgfutil@ifnextchar #1#2#3->\let \pgfutil@reserved@d =#1\def \pgfutil@reserved@a {
                                                                                  #2}\def \pgf
util@reserved@b {#3}\futurelet \pgfutil@let@token \pgfutil@ifnch
l.54 \end{array}\right)$},x=2.5cm,y=2.5cm]{v0}

If you say, e.g., `\def\a1{...}', then you must always
put `1' after `\a', since control sequence names are
made up of letters only. The macro here has not been
followed by the required stuff, so I'm ignoring it.

! Use of \tikz@@scope@env doesn't match its definition.

[...]

!  ==> Fatal error occurred, no output PDF file produced!

Latex error

The command to install dot2tex:

sage -i dot2tex-2.8.7-2

As the documentation of G.layout_graphviz() says, install graphviz >= 2.14 so that the programs dot, neato, ... are in your path. This allows the following to work:

sage: m = matrix(3, range(9))
sage: m.set_immutable()
sage: G = Graph()
sage: G.add_vertex(m)
sage: G.set_latex_options(format='dot2tex')
sage: view(G)

To obtain the tikz code:

sage: tikz_string = G.latex_options().dot2tex_picture()
sage: print tikz_string
\begin{tikzpicture}[>=latex,line join=bevel,]
%%
\node (012345678) at (34bp,22bp) [draw,draw=none]
{$\left(\begin{array}{rrr}0 & 1 & 2 \\3 & 4 & 5 \\6 & 7 &
8\end{array}\right)$};
%
\end{tikzpicture}
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