The use of quotation marks when loading a package in R

Question

Is there any reason to prefer the use of quotation marks when loading a package; e.g.

library("MASS")

over loading packages without putting the name in quotes;

library(MASS)

Looking back at some old code, I seem to switch between the two with no noticeable consequences. Is there a best practise recommendation to follow?

[Recommended reading](http://adv-r.had.co.nz/Computing-on-the-language.html#nse-downsides) — RHertel, Apr 22 '16 at 19:48
In addition, if you search the source code of `library()`, you can find this snippet: `if (!character.only) package <- as.character(substitute(package))`. So no matter if you use `library("MASS")` or `library(MASS)` because you didn't change the default argument `character.only = FALSE`, it would convert the package variable to a character type, i.e. they are not different. — Adam Birenbaum, Apr 22 '16 at 20:28

score 13 · Accepted Answer · answered Apr 22 '16 at 20:56

This is an example of non-standard evaluation. I'm not sure there is "best practice" regarding whether you should put packages in quotes. But

If you submit a paper to the Journal of Statistical Software they insist that package names are in quotes
Advanced R programming gives the downsides and also suggests against it.

The argument against

library(MASS)

is that for new users, it's hard to guess what

pkg = "MASS"
library(pkg)

will do.

1 Answers1