any R style guide / checker?

Question

in Python I'm used to having my code "style-checked" by an automatic but configurable tool, called pep8, after the 8th Python enhancement proposal.

in R I don't know. Google has a style guide, but:

• what do most R programmers actually use?
• I still didn't find any program that performs those checks.

---

Dirk, Alex, in your answers you pointed me at pretty printers, but in my opinion that would overdo one thing and not do another: code would be automatically edited to follow the style, while no warnings are issued for poorly chosen identifiers.

Answer 1

There's a formatR package with tidy.source function. I use Emacs with ESS, and follow Hadley's style recommendations. It's hard to compare R with Python, since style is kind of mandatory in Python, unlike R. =)

EDIT
a simple demonstration:

code <- "fn <- function(x, y) { paste(x, '+', y, '-', x+y) }"
tidy.source(text = code)
## not run
fn <- function(x, y) {
    paste(x, "+", y, "-", x + y)
}

Answer 2

I think if you want such a tool, you may have to write it yourself. The reason is that R does not have an equivalent to Python's PEP8; that is, an "official style guide" that has been handed down from on high and is universally followed by the majority of R programmers.

In addition there are a lot of stylistic inconsistencies in the R core itself; this is a consequence of the way in which R evolved as a language. For example, many functions in R core follow the form of foo.bar and were written before the S3 object system came along and used that notation for method dispatch. In hindsight, the naming of these functions should probably be changed in the interests of consistency and clarity, but it is too late to consider that now.

In summary, there is no official "style lint" tool for R because the R Core itself contains enough style lint, of which nothing can be done about, that writing one would be very difficult. For every rule--- "don't do this" ---there would have to be a long list of exceptions--- "except in this case, and this case, and this one, and ..., where it was done for historical purposes".

Answer 3

As for

what do most R programmers actually use

I suspect that quite a few people follow R Core who have a R Coding standards section in the R Internals manual.

Which in a large sense falls back to these sensible Emacs defaults to be used along with ESS. Here is what I use and it is only minimally changed:

;;; C
(add-hook 'c-mode-hook
          ;;(lambda () (c-set-style "bsd")))
          ;;(lambda () (c-set-style "user"))) ; edd or maybe c++ ?
          (lambda () (c-set-style "c++"))) ; edd or maybe c++ ?
;;;; ESS
(add-hook 'ess-mode-hook
          (lambda ()
            (ess-set-style 'C++)
        ;; Because
            ;;                                 DEF GNU BSD K&R C++
            ;; ess-indent-level                  2   2   8   5   4
            ;; ess-continued-statement-offset    2   2   8   5   4
            ;; ess-brace-offset                  0   0  -8  -5  -4
            ;; ess-arg-function-offset           2   4   0   0   0
            ;; ess-expression-offset             4   2   8   5   4
            ;; ess-else-offset                   0   0   0   0   0
            ;; ess-close-brace-offset            0   0   0   0   0
            (add-hook 'local-write-file-hooks
                      (lambda ()
                        (ess-nuke-trailing-whitespace)))))
(setq ess-nuke-trailing-whitespace-p t)

As for a general, tool Xihui's formatR pretty-printer may indeed be the closest. Or just use ESS :)

Answer 4

• lintr - highlights possible syntax and style issues/errors

• CRAN Task View: Reproducible Research - Formatting Tools section contains other useful tools, particularly formatR which can automatically formt code.