Using tikz graphdrawing library within RMarkdown … Need to use lualatex engine, but can't get it to work

Question

I have the following code in an rmd file which leverages tikz for diagrams:

---
title: \"TestNonTufteLua\"
author: \"Me\"
output:
          


        

Answer 1

Update: Meanwhile knitr no longer uses tools::texi2dvi but tinytex::latexmk. One therefore has to use options(tinytex.engine = 'lualatex') in a set-up chunk.

---

This is rather tricky, since you are not using tikzDevice but the tikz engine, which uses tools::texi2dvi to convert to PDF. You can change this using options(texi2dvi = "lualatex"). However, the default template does not work with LuaLaTeX. I have therefore created a modified template:

\RequirePackage{luatex85}
\documentclass{article}
\usepackage[luatex,active,tightpage]{preview}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{preview}
%% TIKZ_CODE %%
\end{preview}
\end{document}

And specify that file with engine.opts = list(template = "tikz2pdf.tex"). Putting it all together here my working file:

---
title: "TestNonTufteLua"
author: "Me"
output:
  pdf_document :
    latex_engine: lualatex
---

```{r}
options(texi2dvi = "lualatex")
```

```{r tikTest2, eval = TRUE, engine = "tikz", engine.opts = list(template = "tikz2pdf.tex")}
\usetikzlibrary{graphs, graphdrawing}
\usegdlibrary{layered}
\tikz [gr/.style={gray!50}, font=\bfseries]
\graph [layered layout] {
    % A and F are horizontally aligned if you also set weight=0.5 for A -- C.
    A -- [minimum layers=2] C -- F,
    { [nodes=gr, edges=gr] A -- B -- { E, D -- F } }
};
```

Result:

References:

• how to set engine options
• preview and LuaLaTeX
• knitr using texi2pdf