How to wrap code and the output in markdown (.Rmd)

Question

In my documents in r parts I use long codes like:

```{r}
output <- "very long query for example url to some website............................................."
output
```

Is there any way not to make R wrap the code automatically, let's say after 60 characters? I tried tidy=TRUE, tidy.opts=list(width.cutoff=60) option but it doesn't work.

And I want the same with output, because the output of my query is some text. I want to display the whole content in many lines, not just the begining in one line. How can I do it?

Answer 1

I had this same issue until I realized that one needs to install the R package formatR. Once you install and load this package, use tidy=TRUE, tidy.opts=list(width.cutoff=60) in your chunk, or use the following line of code to set it globally:

knitr::opts_chunk$set(tidy.opts = list(width.cutoff = 60), tidy = TRUE)

Answer 2

Things have changed since 2015, but FWIW given that you are now using rmarkdown_1.8 and knitr_1.20:

1. it is handled properly in the default html output;

2. if you are looking for a pdf output, what you can do is

   • breaking the line to control the code chunk length (if you want to display it) but note that in a character string a \n will be added (in which case you may benefit from using two different code chunks: one for displaying the code another for the outputs);
   • regarding the output, you could set the code chunk option results to 'asis' so the output is handled as if it were a regular piece of text, in which case you can also use paste() or paste0() to use latex tags to tweak how the text is displayed.

So:

1- display the code

{r, eval = F}
output <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, 
    sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
output

2- get the output

{r, results = 'asis', echo = F}
output <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. "
output

Hope this could help.