Using symbol font / math notation in graphviz

Question

[Environment: graphviz 2.38 / Windows 7]

Using dot, I want to produce path diagrams like the following to represent a structural equation model (well, here, just a simple one-factor measurement model). I'd like to use Greek letters for some nodes and edges, and would actually prefer if I could use LaTeX-like notation in the dot file like \ksi, \lambda_1 or \delta_1

This diagram is supposed to represent the three equations

\begin{eqnarray*}
x_{1i} & = & \lambda_1 \xi_{i} + \delta_{1i} \\
x_{2i} & = & \lambda_2 \xi_{i} + \delta_{2i} \\
x_{3i} & = & \lambda_3 \xi_{i} + \delta_{3i} 
\end{eqnarray*}

The closest I've come to this is the following .dot file kludge, where I chose font="Symbol" and replaced the Greek letters by their roman equivalents.

However, this doesn't work with dot -Tpdf or AFAICS any other devices other than Postscript dot -Tps, giving me an .eps file I have to convert to PDF or PNG.

Question: is there anything better for this situation?

digraph threevar {
  rankdir=LR;
  size="8,4";
  node [fontname="Helvetica" fontsize=14 shape=box];
  edge [fontname="Symbol" fontsize=10];
  center=1;
  {rank=min k }
  {rank=same X1 X2 X3 }
  {rank=max z1 z2 z3 }
  z1 [shape=circle fontname="Symbol" label="d1"];
  z2 [shape=circle fontname="Symbol" label="d2"];
  z3 [shape=circle fontname="Symbol" label="d3"];
  k [fontname="Symbol" label="x" shape="ellipse"];
  k -> X1 [label="l1"];
  k -> X2 [label="l2"];
  k -> X3 [label="l3"];
  z1 -> X1;
  z2 -> X2;
  z3 -> X3;
}

Aribold

silly question: why not just write δ₁, δ₂, etc. as literal text, with your file saved with utf8 encoding? Both Greek and subscripts 0 through 9 are available in Unicode for infinitely subscripted labels, so instead of using (Xe)(La)TeX notation, try just using straight up δ₁, δ₂, δ₃, λ₁, λ₂, and λ₃, and then see if dot accepts those? – Kutch

I was hoping that there was a simple, direct way that I had missed somewhere; also, unicode characters are a pain to enter. – Aribold

"Just using the text that you want to see, directly" is about as simple as it gets, but the "pain to enter" part is true if you don't use anything to make your life easier. On Windows, I use I use the free babelstone.co.uk/Software/BabelMap.html to pretty much instantly find any character that I need but can't type. I've not had input pain for years thanks to it. – Kutch

Thanks for this pointer --- I tried some other character mapping apps, but BabelMap is much more useful. – Aribold

@Mike'Pomax'Kamermans Thanks! Your suggestion works like a charm with Emacs' TeX input method. – Abramson

Answer 1

OK, using UTF8 characters directly in the .dot file, I can now avoid the Symbol font kludge (but what I tried for subscripts, e.g., subscript-one, x2081 just have a small box containing '2081')

Here's the revised file, that now works with both -Tpdf and -Tpng. (The UTF8 characters don't appear properly in this post.)

    digraph threevar {
      rankdir=LR;
      size="8,4";
      node [fontsize=14 shape=box];
      edge [fontsize=10];
      center=1;
      {rank=min k }
      {rank=same X1 X2 X3 }
      {rank=max z1 z2 z3 }
      z1 [shape=circle label="d1"];
      z2 [shape=circle label="d2"];
      z3 [shape=circle label="d3"];
      k [label="?" shape="ellipse"];
      k -> X1 [label="?1"];
      k -> X2 [label="?2"];
      k -> X3 [label="?3"];
      z1 -> X1;
      z2 -> X2;
      z3 -> X3;
    }

The result is:

Aribold