How to use LaTeX Code in R Chunk in R-Markdown? - r

Question

I am currently writing on a report with rmarkdown and therefore I want to create sections inside a r code chunk. I figured out that this is possible with the help of cat() and results="asis". My problem with this solution is, that my R code results and code isn't properly displayed as usual.
For example
---
title: "test"
output: pdf_document
---
```{r, results='asis'}
for (i in 1:10) {
cat("\\section{Part:", i, "}")
summary(X)
$\alpha = `r X[1,i]`$
}
```
pretty much does the trick, but here there are still two problems:
the R output for summary() is displayed very strange because I guess it`s interpreted as LaTeX code
I can't use LaTeX formulas in this enviroment, so if I want every section to end with a equation, which also might use a R variable, this is not possible
Does somebody know a solution for some of these problems, or is there even a workaround to create sections within a loop and to have R code, R output and LaTeX formulas in this section? Or maybe at least one of those things?
I am very thankful for every kind of advice

Answer 1

You can do what you are after inline without relying as much on code blocks.
As a minimal example.
---
title: "test"
output: pdf_document
---
```{r sect1_prep, include=FALSE}
i <- 1
```
\section{`r paste0("Part: ", i)`}
```{r sect1_body}
summary(mtcars[, i])
```
$\alpha = `r mtcars[1, i]`$
```{r sect2_prep, include=FALSE}
i <- i + 1
```
\section{`r paste0("Part: ", i)`}
```{r sect2_body}
summary(mtcars[, i])
```
$\alpha = `r mtcars[1, i]`$
Produces...
If you really want to have a section factory, you could consider pander.
---
title: "test"
output: pdf_document
---
```{r setup, include=FALSE}
library(pander)
panderOptions('knitr.auto.asis', FALSE)
```
```{r, results='asis', echo=FALSE}
empty <- lapply(1:10, function(x) {
pandoc.header(paste0("Part: ", x), level = 2)
pander(summary(mtcars[, x]))
pander(paste0("$\\alpha = ", mtcars[1, x], "$\n"))
})
```
which produces...
remove summary table format example
---
title: "test"
output: pdf_document
---
```{r setup, include=FALSE}
library(pander)
panderOptions('knitr.auto.asis', FALSE)
```
```{r, results='asis', echo=FALSE}
content <- lapply(1:10, function(x) {
head <- pandoc.header.return(paste0("Part: ", x), level = 2)
body1 <- pandoc.verbatim.return(attr(summary(mtcars[, x]), "names"))
body2 <- pandoc.verbatim.return(summary(mtcars[, x]))
eqn <- pander_return(paste0("$\\alpha = ", mtcars[1, x], "$"))
return(list(head = head, body1 = body1, body2 = body2, eqn = eqn))
})
writeLines(unlist(content), sep = "\n\n")
```