Which functions in R base call internal code?
In a recent question on Stack Overflow about speeding up group-by operations, Marek wondered which functions called .Internal code (and consequently were fast). I was surprised to see that there appears to be no built-in way to check whether or not this is the case (though is.primitive is available for primitive functions).
Writing such a function is quite straight forward. We simply examine the contents of the function body, and search for the string “.Internal” within it.
callsInternalCode <- function(fn)
{
if(!require(stringr)) stop("stringr package required")
any(str_detect(capture.output(body(fn)), "\\.Internal"))
}
You can retrieve all the functions in the base package with this one-liner taken from an example on the Filter help page.
funs <- Filter(is.function, sapply(ls(baseenv()), get, baseenv()))
Now getting the list of functions that call internal code is easy.
names(funs)[sapply(funs, callsInternalCode)]
[1] "abbreviate" "agrep"
[3] "all.names" "all.vars"
[5] "anyDuplicated.default" "aperm"
...
EDIT: Tweaked the regex (the ‘.’ should have been escaped.)
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Richie Cotton
Licensing
The non-code parts of 4D Pie Charts by Richard Cotton are licensed under a Creative Commons Attribution-NoDerivs 2.0 UK: England & Wales License. The code parts of the blog are licensed under the WTFPL v2.0.
Nice function, thanks for sharing it!
I wonder how this might reflect on the issue recently raised with optimizing R (I just asked about it here: http://stackoverflow.com/questions/3706990/is-r-that-bad-that-it-should-be-rewritten-from-scratch)
Running this code and some games on it shows we have 28% of the functions using internals and 17% of the functions using “for” loop.
I do wonder what this means in terms of chances for improvement…
Here’s the code I used:
callsInternalCode <- function(fn) { if(!require(stringr)) stop("stringr package required") any(str_detect(capture.output(body(fn)), ".Internal")) } callsfor <- function(fn) { if(!require(stringr)) stop("stringr package required") any(str_detect(capture.output(body(fn)), "for")) } funs <- Filter(is.function, sapply(ls(baseenv()), get, baseenv())) #names(funs)[sapply(funs, callsInternalCode)] length(names(funs)[sapply(funs, callsInternalCode)]) / length(funs) length(names(funs)[sapply(funs, callsfor )]) / length(funs)I like it very match.
Don’t forget about other ways to call internal functions: `.Primitive`, `.C`, `.Fortran`, `.External`, `.Call`.
Glad you like the function. For the record, under R2.11.1 I find 1140 functions in the base environment, of which
323 call .Internal
178 call .Primitive
30 call .Call
11 call .Fortran
7 call .C
0 call .External (this is the equivalent of .Internal for non-R-core developers)