Capture 'output_format' from rmarkdown::render as variable

Question

I am using RStudio with knitr, etc, to make reproducible reports, and want to have the best versions I can for both Word documents and PDF - I prefer working with LaTeX, but the end-users tend to prefer the flexibility of editable Word documents.

I have written a ifelse statement that essentially says 'if this is rendered as a word document, create a kable table in markdown, else create the kable table in LaTeX and then manipulate to make the table look better (shaded rows, etc)'.

I don't understand how the rmarkdown::rendering process works to capture the output_format, but is there a way to store this as a variable and use in the ifelse statement?

A minimal example would be to save this code as test.Rmd:

format <- output_format #(somehow captured as a variable)

printTable <- function(data = df, format = format){

if (format %in% 'pdf_document') {

    # create nice latex table

} else {

    # create markdown table

}
}

Then, when running this code:

rmarkdown::render(input = "test.Rmd", output_format = c("word_document", "pdf_document"))

the different versions of the report would have the correct tables included.

Answer 1

You can access the output format via knitr::opts_knit$get("rmarkdown.pandoc.to"). This will return a string with the target output format. Here's an example:

---
title: "Untitled"
output: html_document
---

```{r}
library(knitr)
opts_knit$get("rmarkdown.pandoc.to")
```

This returns "html" for html_document, "docx" for word_document, and "latex" for pdf_document.