Code Chunk Font Size in Rmarkdown with Knitr and Latex

Code chunk font size in Rmarkdown with knitr and latex

Picking up the idea to alter a knitr hook we can do the following:

def.chunk.hook  <- knitr::knit_hooks$get("chunk")
knitr::knit_hooks$set(chunk = function(x, options) {
  x <- def.chunk.hook(x, options)
  ifelse(options$size != "normalsize", paste0("\n \\", options$size,"\n\n", x, "\n\n \\normalsize"), x)
})

This snippet modifies the default chunk hook. It simply checks if the chunk option size is not equal to its default (normalsize) and if so, prepends the value of options$size to the output of the code chunk (including the source!) and appends \\normalsize in order to switch back.

So if you would add size="tiny" to a chunk, then all the output generated by this chunk will be printed that way.

All you have to do is to include this snippet at the beginning of your document.

Code chunk font size in Beamer with knitr and latex

Drawing on this tex.SE answer, we could redefine the Shaded environment that surrounds R code to make it footnotesize (and the verbatim environment for output). Add this to your header.txt:

%% change fontsize of R code
\let\oldShaded\Shaded
\let\endoldShaded\endShaded
\renewenvironment{Shaded}{\footnotesize\oldShaded}{\endoldShaded}

%% change fontsize of output
\let\oldverbatim\verbatim
\let\endoldverbatim\endverbatim
\renewenvironment{verbatim}{\footnotesize\oldverbatim}{\endoldverbatim}

How can I control fontsize and linestretch of code chunks independently from the main text in bookdown?

It's is the same idea as here but now we just alter the source hook:

```{r setup, include=FALSE}
def.source.hook  <- knitr::knit_hooks$get("source")
knitr::knit_hooks$set(source = function(x, options) {
  x <- def.source.hook(x, options)  # apply default source hook
  ifelse(!is.null(options$linestretch),  # if linestretch is not NULL, apply linestretch
         paste0("\\linespread{", options$linestretch,"}\n", x, "\n\n\\linespread{1}"),  # reset linestretch after the chunk!
         x)
})
```

Now you can copy and paste the ifelse statement from the other answer into this hook as well and you can control both.

Full example:

---
title: "Linestretch"
date: "20 December 2018"
header-includes:
  - \usepackage{lipsum}
output: 
  bookdown::pdf_document2:
    keep_tex: true
linestretch: "`r (lstr <- 1.5)`" 
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(eval = F)
def.source.hook  <- knitr::knit_hooks$get("source")
knitr::knit_hooks$set(source = function(x, options) {
  x <- def.source.hook(x, options)
  x <- ifelse(!is.null(options$linestretch), 
              paste0("\\linespread{", options$linestretch,"}\n", x, "\n\n\\linespread{", lstr,"}"), 
              x)
  ifelse(!is.null(options$size), 
         paste0("\\", options$size,"\n\n", x, "\n\n \\normalsize"), 
         x)
})
```

## R Markdown

\lipsum[30]


```{r, linestretch = 1, size="Large"}
head(mtcars)
head(mtcars)
```


\lipsum[30]

---

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