styler

The goal of styler is to provide non-invasive pretty-printing of R
source code while adhering to the
tidyverse formatting rules. styler can be
customized to format code according to other style guides too.

Installation

You can install the package from CRAN:

install.packages("styler")

Or get the development version from GitHub:

# install.packages("remotes")
remotes::install_github("r-lib/styler")

API

You can style a simple character vector of code with style_text():

library("styler")
ugly_code <- "a=function( x){1+1}           "
style_text(ugly_code)
#> a <- function(x) {
#>   1 + 1
#> }

There are a few variants of style_text():

• style_file() styles .R and/or .Rmd files.
• style_dir() styles all .R and/or .Rmd files in a directory.
• style_pkg() styles the source files of an R package.
• RStudio Addins for styling the active file, styling the current
  package and styling the highlighted code
  region.

Functionality of styler

scope

You can decide on the level of invasiveness with the scope argument. You
can style:

• just spaces.
• spaces and indention.
• spaces, indention and line breaks.
• spaces, indention, line breaks and tokens.

ugly_code <- "a=function( x){1+1}           "
style_text(ugly_code, scope = "spaces")
#> a = function(x) {1 + 1}

Note that compared to the default used above scope = "tokens":

• no line breaks were added.
• <- was not replaced with =.

While spaces still got styled (around = in (x)).

strict

If you wish to keep alignment as is, you can use strict = FALSE:

style_text(
  c(
    "first  <- 4",
    "second <- 1+1"
  ),
  strict = FALSE
)
#> first  <- 4
#> second <- 1 + 1

This was just the tip of the iceberg. Learn more about customization
with the tidyverse style guide in in this
vignette. If
this is not flexible enough for you, you can implement your own style
guide, as explained in the corresponding
vignette.

Adaption of styler

styler functionality is made available through other packages, most
notably

• usethis::use_tidy_style() styles your project according to the
  tidyverse style guide.
• reprex::reprex(style = TRUE) to prettify reprex code before
  printing. To permanently use style = TRUE without specifying it
  every time, you can add the following line to your .Rprofile (via
  usethis::edit_r_profile()): options(reprex.styler = TRUE).
• you can pretty-print your R code in RMarkdown reports without having
  styler modifying the source. This feature is implemented as a code
  chunk option in knitr. use tidy = "styler" in the header of a code
  chunks (e.g. ```{r name-of-the-chunk, tidy = "styler"}), or
  knitr::opts_chunk$set(tidy = "styler") at the top of your
  RMarkdown script.
• as a pre-commit hook style-files in
  https://github.com/lorenzwalthert/pre-commit-hooks.
• pretty-printing of drake
  workflow data frames with drake::drake_plan_source().
• Adding styler as a fixer to the ale
  Plug-in
  for VIM.

Further resources

• The official web documentation of
  styler, containing various vignettes function documentation as well
  as a change-log.
• Blog
  post
  about how you can customize styler without being an expert.
• A tidyverse.org blog
  post
  introducing the functionality of styler.
• The wiki of Google Summer of Code
  2017
  or the pkgdown page contain
  information related to the initial development phase during Google
  Summer of Code 2017.