将 tikz 图表 latex 代码添加到 Rmarkdown

Question

如何将以下 Latex 代码包含到 Rmarkdown 中？

\usetikzlibrary{shapes.geometric,arrows}

\tikzstyle{decision} = [ diamond, draw, fill=blue!20, text width=4.5em, text badly centered, node distance=3cm, inner sep-0pt]  
\tikzstyle{block} = [ rectangle, draw, fill=blue!20, text width=5em, text badly centered, rounded corners, minimum height=4em]  
\tikzstyle{line} = [ draw, -latex']  
\tikzstyle{terminator} = [ draw, ellipse, fill=red!20, node distance=3cm, minimum height=2em]  

    \begin{tikzpicture}[node distance=2cm, auto]  
      \node [terminator]           (puc)  {Power-Up Reset};  
      \node [block, below of=puc]  (wdt)  {Stop Watchdog};  
      \node [block, below of=wdt]  (port) {Setup Port Pins};  
      \node [block, below of=port] (loop) {Loop Forever};  
      \path [line] (puc)  -- (wdt);  
      \path [line] (wdt)  -- (port);  
      \path [line] (port) -- (loop);  
      \path [line] (loop) -- (loop);  
    \end{tikzpicture}

Answer 1

请始终包含一个最小的可重现示例：参见这里和那里

在文件中tikz.Rmd

---
title: "Title"
author: "Me"
header-includes:
   - \usepackage{tikz}
   - \usetikzlibrary{shapes.geometric,arrows}
output:
  pdf_document 
---


\begin{tikzpicture}[node distance=2cm, auto]  
\tikzstyle{decision}=[diamond, draw, fill=blue!20, text width=4.5em, text badly centered, node distance=3cm, inner sep-0pt]  
\tikzstyle{block}=[rectangle, draw, fill=blue!20, text width=5em, text badly centered, rounded corners, minimum height=4em]  
\tikzstyle{line}=[draw, -latex']  
\tikzstyle{terminator} = [ draw, ellipse, fill=red!20, node distance=3cm, minimum height=2em]    
\node [terminator] (puc) {Power-Up Reset};  
\node [block, below of=puc] (wdt)  {Stop Watchdog};  
\node [block, below of=wdt] (port) {Setup Port Pins};  
\node [block, below of=port] (loop) {Loop Forever};  
\path [line] (puc)  -- (wdt);  
\path [line] (wdt)  -- (port);  
\path [line] (port) -- (loop);  
\path [line] (loop) -- (loop);  
\end{tikzpicture}

Answer 2

该示例的一个微小变化，但在 knitr 块中使用 TikZ 代码：

---
title: "Latex and TikZ in knitr chunks"
author: "Me"
header-includes:
   - \usepackage{xspace}
   - \usepackage{tikz}
   - \usetikzlibrary{shapes.geometric,arrows}
   - \def\TikZ{Ti\emph{k}Z\ }
output:
  pdf_document 
---

## TikZ directly on the notebook

\begin{tikzpicture}[node distance=2cm, auto]  
    \tikzstyle{decision}=[diamond, draw, fill=blue!20, text width=4.5em, text badly centered, node distance=3cm, inner sep-0pt]  
    \tikzstyle{block}=[rectangle, draw, fill=blue!20, text width=5em, text badly centered, rounded corners, minimum height=4em]  
    \tikzstyle{line}=[draw, -latex']  
    \tikzstyle{terminator} = [ draw, ellipse, fill=red!20, node distance=3cm, minimum height=2em]    
    \node [terminator] (puc) {Power-Up Reset};  
    \node [block, below of=puc] (wdt)  {Stop Watchdog};  
    \node [block, below of=wdt] (port) {Setup Port Pins};  
    \node [block, below of=port] (loop) {Loop Forever};  
    \path [line] (puc)  -- (wdt);  
    \path [line] (wdt)  -- (port);  
    \path [line] (port) -- (loop);  
    \path [line] (loop) -- (loop);  
\end{tikzpicture}


## \TikZ code inside a knitr chunk

The \LaTeX code can also be included in a knitr chunk with small changes:

* The \TikZ engine has to be specified
* The \TikZ libraries have to be called from within the chunk


```{tikz, echo=FALSE, fig.align="center"}

\usetikzlibrary{shapes.geometric,arrows}

\begin{tikzpicture}[node distance=2cm, auto]  
    \tikzstyle{decision} = [diamond, 
                          draw, 
                          fill=blue!20, 
                          text width=4.5em, 
                          text badly centered, 
                          node distance=3cm, 
                          inner sep-0pt]  
    \tikzstyle{block} = [rectangle, 
                         draw, 
                         fill=blue!20, 
                         text width=5em, 
                         text badly centered, 
                         rounded corners, 
                         minimum height=4em]  
    \tikzstyle{line} = [draw, -latex']  
    \tikzstyle{terminator} = [draw, 
                        ellipse, 
                        fill=red!20, 
                        node distance=3cm, 
                        minimum height=2em]    

    \node [terminator] (puc) {Power-Up Reset};  
    \node [block, below of=puc] (wdt)  {Stop Watchdog};  
    \node [block, below of=wdt] (port) {Setup Port Pins};  
    \node [block, below of=port] (loop) {Loop Forever};  
    \path [line] (puc)  -- (wdt);  
    \path [line] (wdt)  -- (port);  
    \path [line] (port) -- (loop);  
    \path [line] (loop) -- (loop);  
\end{tikzpicture}
```