CODEWITHSUNDEEP
rlatexknitrr-markdown
ssp3nc3r
ssp3nc3r

Reputation: 3822

Decorating .Rmd code chunk with latex using knitr

I'm trying to add latex code surrounding r-markdown (.Rmd) code chunks. I can do this by manually editing the .tex file generated by knitr as follows,

\usepackage{fancyvrb}
\usepackage{xcolor}
\usepackage{changepage}




{
\color{gray}
\footnotesize
\begin{adjustwidth}{2cm}{2cm}
\noindent\rule{1cm}{1.5pt} R code \noindent\rule{8cm}{0.3pt}
\begin{verbatim}

\end{verbatim}
\noindent\rule{8cm}{0.3pt}
\end{adjustwidth}
}

where \begin{verbatim} begins a code chunk that, in turn, ends with \end{verbatim}. I'd like to avoid manually re-coding this latex decoration manually each time I knit.

It appears that I can place the package information in the YAML header of the .Rmd:

---
header-includes:
  - \usepackage{fancyvrb}
  - \usepackage{xcolor}
  - \usepackage{changepage}
---

But I'm not getting the hook setup right. I've tried to modify the hook described here, as follows,

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

def.chunk.hook  <- knitr::knit_hooks$get("chunk")

knitr::knit_hooks$set(chunk = function(x, options) {
  x <- def.chunk.hook(x, options)
  paste0(
"{\n\\color{gray}\n\\footnotesize\n\\begin{adjustwidth}{1cm}{1cm}\n\\noindent\\rule{1cm}{1.5pt} R code \\noindent\\rule{8cm}{0.3pt}\n",
x,
"\n\n\\noindent\\rule{8cm}{0.3pt}\n\\end{adjustwidth}\n}\n"
  )
}
)
```

which threw an error. Any suggestions appreciated.

UPDATE:

I am able to change R chunk font color, size and indention by adding the following to my YAML header:

header-includes:
  - \usepackage{changepage}
  - \usepackage{xcolor}
  - \usepackage{etoolbox}\BeforeBeginEnvironment{verbatim}{\begingroup\color{gray}\footnotesize\begin{adjustwidth}{.5cm}{.5cm}}\AfterEndEnvironment{verbatim}{\end{adjustwidth}\endgroup}

With that, I think there's no need to use the knitr hook function. Perhaps I've overlooked a cleaner approach, though, which allows me to make whatever mods I like.

Upvotes: 1

Views: 891

Answers (1)

Cedric
Cedric

Reputation: 2474

When running from an Rnw, the knir hook is different

> def.chunk.hook
function (x, options) 
{
    ai = output_asis(x, options)
    col = if (!ai) 
        paste0(color_def(options$background), if (!is_tikz_dev(options)) 
            "\\color{fgcolor}")
    k1 = paste0(col, "\\begin{kframe}\n")
    k2 = "\\end{kframe}"
    x = .rm.empty.envir(paste0(k1, x, k2))
    size = if (options$size == "normalsize") 
        ""
    else sprintf("\\%s", options$size)
    if (!ai) 
        x = sprintf("\\begin{knitrout}%s\n%s\n\\end{knitrout}", 
            size, x)
    if (options$split) {
        name = fig_path(".tex", options, NULL)
        if (!file.exists(dirname(name))) 
            dir.create(dirname(name))
        cat(x, file = name)
        sprintf("\\input{%s}", name)
    }
    else x
}
<environment: namespace:knitr>

from that obtained when running Rmd>md>tex(pandoc)

function (x, options) 
{
    x = gsub(paste0("[\n]{2,}(", fence, "|    )"), "\n\n\\1", 
        x)
    x = gsub("[\n]+$", "", x)
    x = gsub("^[\n]+", "\n", x)
    if (isTRUE(options$collapse)) {
        x = gsub(paste0("\n([", fence_char, "]{3,})\n+\\1(", 
            tolower(options$engine), ")?\n"), "\n", x)
    }
    if (is.null(s <- options$indent)) 
        return(x)
    line_prompt(x, prompt = s, continue = s)
}
<environment: 0x000000003777c250>

While the tex file is structured ok

{
\color{gray}
\footnotesize
\begin{adjustwidth}{1cm}{1cm}
\noindent\rule{1cm}{1.5pt} R code \noindent\rule{8cm}{0.3pt}
\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{alltt}
\hlstd{data} \hlkwb{<-} \hlnum{1}
\end{alltt}
\end{kframe}
\end{knitrout}

\noindent\rule{8cm}{0.3pt}
\end{adjustwidth}
}

And produces some expected output. code decoration the .md is not and will not easily be transfered to pdf (via tex).

{
\color{gray}
\footnotesize
\begin{adjustwidth}{1cm}{1cm}
\noindent\rule{1cm}{1.5pt} R code \noindent\rule{8cm}{0.3pt}

```r
data <- 1
```

\noindent\rule{8cm}{0.3pt}
\end{adjustwidth}

}

Upvotes: 1

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