[R] Rd file processing suggestion - % sign in examples

Peter Langfelder peter.langfelder at gmail.com
Tue Apr 19 08:26:35 CEST 2011

Hi folks,

I have come across a simple quirk that took me a long time to figure
out. The gist is that if I write, in the example section of an Rd
file, the line

c = a %*% b

what R will see when running the example is

c = a

since the % signs are apparently considered comment signs even in the
\examples section. The change from c = a %*% b to c = a can easily
make the example code fail with an error further down the line. The
thing is, if you take the code and copy-paste it into a standard R
session, the code will run correctly (which is what happened to me and
it took me several hours to figure this mystery out). The solution is
to escape the % signs by a backslash, i.e. to write c = a \%*\% b

The suggestion is (of course) to make the Rd processor/parser not
consider % sign a comment sign in the examples section. Hopefully that
wouldn't be too difficult...



More information about the R-help mailing list