How can I count lines of code in an R package?

How can I count the lines of code in an R package? I have two possible types of input:

• The raw package code (my own package); I could point the function to the R folder that contains source code.
• The tar.gz package file; I could enter that as input to the function.

In either case, I specifically want the number of lines of code while skipping comment lines and blank lines. I don't need the number of comment lines, but if the function provides these, that would be fine. A function that counts these lines as a secondary function might also be good, as long as the secondary function does not take too much time.

I prefer an R function (run from within R) rather than a command line or terminal command (run from outside R). The function must recognize R comments.

We can start developing something from

1) With readLines()

count = \(p) {
  l = readLines(p) # warn=FALSE
  length(l[!grepl('^\\s*(#.*)?$', l)])
}

readLines() might through warning(s)

In readLines(p) : incomplete final line found on './blahblah.R'

This should be due to missing End Of Line (EOL) and can be ignored.

2) With scan()

count2 = \(p) {
  l = scan(p, what='', sep='\n', blank.lines.skip=TRUE)
  length(l[!grepl('^\\s*#', l)])
}

Apply

r = list.files(path='>top_level_folder<', pattern='.R$', full.names=TRUE, recursive=TRUE)
sum(sapply(r, count))
sum(sapply(r, count2))

As User @SamR points out in a comment below this answer, there is {cloc}. You might want to check it out.