[ESS] Customizing the Syntax Highlighting in R

S. McKay Curtis smcurtis at stat.washington.edu
Thu Mar 25 19:53:40 CET 2010

I don't know how to send a screenshot to the entire list (do I just
send an attachment?), so here's a link to a screenshot instead:


In the shot, functions like "do.call" and "write.table" are
highlighted blue, whereas they would not be highlighted at all under
the ESS defaults.

Of course, notice that argument names like "quote" and "row.names" in
the "write.table" function are also highlighted, even though I wish
they were not.  They are highlighted because the argument names happen
to be the names of functions too.  This would be easy to fix in the
regular expressions for syntax highlighting if only Emacs' regular
expressions had "lookahead".  But Emacs doesn't have lookahead.  Oh

On Thu, Mar 25, 2010 at 10:32 AM, Erik Iverson <eriki at ccbr.umn.edu> wrote:
> Could you be so kind as to put a screenshot up of the results of this?
> S. McKay Curtis wrote:
>> I've finally figured out a less hackish way of customizing the syntax
>> highlighting in R.  Unfortunately, Emacs's regular expression
>> implementation does not have "lookahead," so more words are
>> highlighted than I would prefer, specifically, options in functions
>> that happen to have the same name as an R function are also
>> highlighted.  One way to avoid this is to include the opening
>> parenthesis in the regular expression for the syntax highlighting, but
>> the solution then becomes a problem --- having that opening
>> parenthesis highlighted is a minor annoyance.  So if any one has any
>> bright ideas on how to fix that I would appreciate hearing them.
>> Anyway, here's how to customize the syntax highlighting for R:
>> 1) Run the following lines of code in R.  The R code will create a
>> text file with the names of all the functions in the base, stats, and
>> utils R packages.  If you would like more syntax highlighting for
>> functions in other commonly used packages, you can add other packages
>> by modifying the code.  The code stores the text file in the
>> ".emacs.d" directory, but you can modify the code to store this file
>> wherever you prefer.  (Truth be told, I don't really know what the
>> .emacs.d directory is really supposed to be used for... It just
>> magically appeared one day, so I use it.)
>> ## Get R function names from packages base, stat, and utils
>> ## and store them in a file for ESS to use for font locking / syntax
>> highlighting
>> obj <- do.call("c", sapply(c("package:base", "package:stats",
>> "package:utils"), objects, all.names=TRUE))
>> re <- "(^[^.[:alpha:][:digit:]]|<-|__)"  # to remove "weird" functions
>> obj <- obj[-grep(re, obj)]
>> fpath <- file.path(Sys.getenv("HOME"), ".emacs.d", "R-function-names.txt")
>> write.table(obj, fpath, quote=FALSE, row.names=FALSE, col.names=FALSE)
>> 2) Add the following lines of code to your .emacs file:
>> ;; Read a whole file into list of lines
>> ;; Author: Xah Lee
>> ;; see http://xahlee.org/emacs/elisp_process_lines.html
>> (defun read-lines (file)
>>  "Return a list of lines in FILE."
>>  (with-temp-buffer
>>    (insert-file-contents file)
>>    (split-string
>>     (buffer-string) "\n" t)
>>    )
>>  )
>> (add-hook 'ess-mode-hook
>>          '(lambda()
>>             (setq ess-my-extra-R-function-keywords
>>                   (read-lines "~/.emacs.d/R-function-names.txt"))
>>             (setq ess-R-mode-font-lock-keywords
>>                   (append ess-R-mode-font-lock-keywords
>>                           (list (cons (concat "\\<" (regexp-opt
>> ess-my-extra-R-function-keywords 'enc-paren) "\\>")
>>                                       'font-lock-function-name-face))))))
>> If you don't like the particular color, you can change the "
>> 'font-lock-function-name-face " to something else (see the code in
>> ess-custom.el file).
>> 3) Enjoy the dazzling display of colors in R.
>> On Sat, Nov 21, 2009 at 9:48 AM, S. McKay Curtis
>> <smcurtis at stat.washington.edu> wrote:
>>> Hi Paul,
>>> This hack worked for me
>>> http://old.nabble.com/Font-locking-td22839833.html
>>> although I admit it's not very pretty.
>>> McKay
>>> On Fri, Nov 20, 2009 at 7:17 PM, Paul Heinrich Dietrich
>>> <paul.heinrich.dietrich at gmail.com> wrote:
>>>> I'm coming over to Emacs after using gvim, in which I built a R syntax
>>>> highlighting file with thousands of keywords, because I routinely use
>>>> numerous R packages.  In the default for Emacs + ESS, I see highlighting
>>>> for
>>>> only a few things, such as <-, TRUE, if, and for.  For example, I would
>>>> like
>>>> to add the following R functions as keywords, such as length, round,
>>>> nrow,
>>>> names, and read.csv in the colour red.  Thank you for any suggestions.
>>>> Stephen Eglen wrote:
>>>>> I don't think there is an easy way to do this -- there is the variable
>>>>> inferior-ess-R-font-lock-keywords
>>>>> but that is not easy for a beginner to edit.  Could you give an example
>>>>> of what you would like highlighted and in what colour?
>>>>> ______________________________________________
>>>>> ESS-help at stat.math.ethz.ch mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/ess-help
>>>> --
>>>> View this message in context:
>>>> http://old.nabble.com/Customizing-the-Syntax-Highlighting-in-R-tp26443563p26453433.html
>>>> Sent from the ESS - Help mailing list archive at Nabble.com.
>>>> ______________________________________________
>>>> ESS-help at stat.math.ethz.ch mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/ess-help
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>> https://stat.ethz.ch/mailman/listinfo/ess-help

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