[R] Extracting File Basename without Extension

[Rau, Roland]

Hi, 

> [mailto:r-help-bounces at r-project.org] On Behalf Of Henrique 
> Dallazuanna
> 
> Try this also:
> 
> substr(basename(myfile), 1, nchar(basename(myfile)) - 4)
> 

This, of course, assumes that the extensions are always 3 characters.
Sometimes there might be more ("index.html"), sometimes less
("shellscript.sh").

Although my solution is not as compact as the others (I wish I was
proficient in 'mastering regular expressions'), I'd like to provide my
little code-snippet which does not require any regular expressions (but
expects a . in the filename).

######################
x1 <- "roland.txt"
x2 <- "roland.html"
x3 <- "roland.sh"

no.extension <- function(astring) {
  if (substr(astring, nchar(astring), nchar(astring))==".") {
    return(substr(astring, 1, nchar(astring)-1))
  } else {
    no.extension(substr(astring, 1, nchar(astring)-1))
  }
}

no.extension(x1)
no.extension(x2)
no.extension(x3)
######################

Hope this helps a bit,
Roland

P.S. Any suggestions how to become more proficient with regular
expressions? The O'Reilly book ("Mastering...")? Whenever I tried
anything more complicated than basic usage (things like ^ $ * . ) in R,
I was way faster to write a new function (like above) instead of finding
a regex solution.

By the way: it might be still possible to *write* regular expressions,
but what about code re-use? Are there people who can easily *read*
complicated regular expressions?

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