Change default prompt and output line prefix in R?

user_165787 0
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For the purposes of teaching and preparing written instructions about R, one of the things that's always frustrated me is that I can't simply copy commands and output from R and paste them into another R session. For example, if I do something trivial, such as

> x <- rnorm(10)
> x
 [1]  1.76975998  1.19722850 -0.39274507 -1.10979974  0.52320473 -0.08643833
 [7]  0.94437690  0.08083207  0.62260363  1.89305469

If I copy and paste that into a document or even here in this post, you (and my students) can not then just highlight it, copy it and paste it into an R session successfully

> > x <- rnorm(10)
Error: syntax error
> > x
Error: syntax error
>  [1]  1.76975998  1.19722850 -0.39274507 -1.10979974  0.52320473 -0.08643833
Error: syntax error
>  [7]  0.94437690  0.08083207  0.62260363  1.89305469
Error: syntax error

You might want to do this to test your installation of R, compare my output to yours, or simply to make use of a function I've offered.

So, what I'd like to be able to do is to change the default prompt from > to either an empty string or a blank space and also prefix all output lines with a hash mark #. That way, I could use R interactively to generate a session that looks like

x <- rnorm(10)
x
# [1]  1.76975998  1.19722850 -0.39274507 -1.10979974  0.52320473 -0.08643833
# [7]  0.94437690  0.08083207  0.62260363  1.89305469

which could be copy/pasted into an R session successfully. It would make prepping R code for a journal article, students, lectures, etc. much easier for me (and maybe for others?)

I've poked around the documentation with no luck... any ideas? pointers?

Currently, I'm using R on a Mac either via the R.app GUI or from Terminal.

r
11 Answers

Coming in very late to the game, just pointing out that almost anything desired can be put into a prompt. Homage to many unix programmers' shell prompt:

options(prompt = paste0(getwd(),'\n> '))

Probably a way to toss colors in there too.

user_8843720

Similar to the chosen answer this has been put into an RStudio Addin called mischelper (https://github.com/dracodoc/mischelper) where one of its functions does this exactly. The benefit of having it as an Addin is that you can turn it into a keyboard shortcut which I think is missing from the other solutions posted here. Usually paste is Ctrl + V so I have script/code I wanted copied in from the console as Ctrl + B. It pastes:

> x <- rnorm(10)
> x
 [1] -1.5337  0.7866  0.2721 -1.9644  0.0648  1.1001 -0.1761 -0.9213 -1.5025  1.3947

as:

x <- rnorm(10)
x
#  [1] -1.5337  0.7866  0.2721 -1.9644  0.0648  1.1001 -0.1761 -0.9213 -1.5025  1.3947

Might be helpful to someone....

user_40837430
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