One of My Favorite R Oddities: dump()

[This article was first published on librestats » R, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

R is full of things that make “real programmers” (I dislike this term) turn their noses up in disgust. One of my favorites is the dump() function. It is…odd. I think the best way to introduce it to people is without context, because it’s just so bizarre:

x <- runif(5)

# [1] 0.7169493 0.1615495 0.7741029 0.4234200 0.8732784

dump("x", stdout())
# x <-
# c(0.716949315741658, 0.161549518117681, 0.774102924391627, 0.423419966362417, 
# 0.873278449522331)

y <- matrix(1:30, 10)
dump("y", stdout())
# y <-
# structure(1:30, .Dim = c(10L, 3L))

That's right; it's actually dumping out R code that would allow you to generate the object. I have actually even found some intersting uses for this in my time developing R packages. But they are highly unusual, and generally I would recommend you rethink your strategy if you think this looks like a solution to your problems. Still, it's pretty cool to have!

But this allows for another amusing oddity with R: you can modify R objects with a text editor inside the R terminal itself. Here's a simple example:

x <- 1:5

Entering this into an R terminal will greet you with a vim editor containing the text:


Now if I change the 5 to a 6 and save/exit, back in R I see:

# [1] 1 2 3 4 5 6

There are also emacs() and xemacs() functions if you're some kind of filthy emacs plebian. I mean, they probably work. I wouldn't know:

$ apt-cache policy emacs
  Installed: (none)

Now these editor commands (vi(), emacs(), ...) sort of work in RStudio, but not really (you just get a plain editor window). So you will have to use your terminal to really enjoy this one.

Speaking of RStudio, did you know that it has a vim mode? It's far from a full vim session, but it's pretty neat. You can enable it by selecting

  • Tools
  • Global Options
  • Code Editing
  • Enable vim editing mode:


Of course, there's a nice R plugin for vim itself.

To leave a comment for the author, please follow the link and comment on their blog: librestats » R. offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)