Tikz in RMarkdown

Question

I have a diagram rendered using tikz and would like to include it at multiple places throughout my document. I have tried to define a command to insert this into the tikz environment, however I'm not very familiar with LaTeX and it doesn't seem to be working.

\newcommand\ThreeStateDiagram{}
\def\ThreeStateDiagram{
  \usetikzlibrary{calc}
  \usetikzlibrary{positioning}
  \usetikzlibrary{arrows}
  \begin{tikzpicture}[
      sharp corners=2pt,
      inner sep=7pt,
      node distance=3cm,
      >=latex]
  \tikzstyle{my node}=[draw,minimum height=1cm,minimum width=2cm]
  \node[my node] (A){A};
  \node[my node,right of=A](C){C};
  \node[my node] at ($(A)!0.5!(C)-(0pt,1.5cm)$) (B) {B};
  \draw[->] (A) -- (B);
  \draw[->] (A) -- (C);
  \draw[->] (B) -- (C);
  \end{tikzpicture}
}

An added bit of difficulty is that I'm writing my document in RMarkdown and using the built-in tikz engine to render it. Here is the code in RMarkdown:

```{tikz, ThreeStateDiagram, fig.cap="Layout Diagram", fig.align="center"}
\ThreeStateDiagram;
`` `

And I can then use \@ref(tab:ThreeStateDiagram) to cross-reference it (because I'm using {bookdown}).

For clarity, the below works fine (in LaTeX, HTML and Word formats), however I don't want to have to insert this (with different captions) repeatedly:

```{tikz, ThreeStateDiagram, fig.cap="Layout of the MSM used in the motivating model", fig.align="center"}
  \usetikzlibrary{calc}
  \usetikzlibrary{positioning}
  \usetikzlibrary{arrows}
    \begin{tikzpicture}[
      sharp corners=2pt,
      inner sep=7pt,
      node distance=3cm,
      >=latex]
  \tikzstyle{my node}=[draw,minimum height=1cm,minimum width=2cm]
  \node[my node] (A){A};
  \node[my node,right of=A](C){C};
  \node[my node] at ($(A)!0.5!(C)-(0pt,1.5cm)$) (B) {B};
  \draw[->] (A) -- (B);
  \draw[->] (A) -- (C);
  \draw[->] (B) -- (C);
  \end{tikzpicture}
`` `   

Answer 1

knitr's tikz engine renders the figure into a pdf file and then includes it via

\begin{figure}
...
\includegraphics{[path-to-pdf-figure]}
...
\end{figure}

which you can check yourself if your specify keep_tex: true in your YAML header output section and examine the resulting *.tex file (_book/_main.tex by default).

If you have named the respective chunk, e.g. as ThreeStateDiagram then the figure is named ThreeStateDiagram-1.pdf

If you are using the bookdown package to manage and render your document, then the figure is stored in _bookdown_files/_main_files/figure_latex/ThreeStateDiagram-1.pdf

If the respective chunk is the nth unnamed chunk, then the figure's filename is unnamed-chunk-[n]-1.pdf (replace n with the actual value) and will be residing in the same directory as mentioned above.

In case your documentclass is beamer or you specified output: bookdown::beamer_presentation2 in your _output.yml, then the path is _bookdown_files/_main_files/figure_beamer/foo-1.pdf

Hence you can reuse the figure in subsequent code in a similar fashion.