# Which functions in R base call internal code?

**4D Pie Charts » R**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

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 serach 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 function 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"
...
```

Tagged: internal, r

**leave a comment**for the author, please follow the link and comment on their blog:

**4D Pie Charts » R**.

R-bloggers.com offers

**daily e-mail updates**about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.