For most purposes a more useful technique is to write the function with a default NULL argument
myfunc <- function(x, ylim=NULL) so that it can be called as myfunc(x) or myfunc(x,y). Inside the function you test for !is.null(ylim) and take appropriate action. Alternatively, and maybe more commonly, you give ylim a sensible default so the caller has to be explicit about setting ylim to NULL if required. As it happens, in your specific case you can write as you did except for the pseudo-line(hasArg(ylim)), because all arguments will get passed to plot, which will itself recognise and test for an argument called ylim, within its own "...". HTH > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: 16 September 2003 15:14 > To: [EMAIL PROTECTED] > Subject: [R] Retrieve ... argument values > > > Security Warning: > If you are not sure an attachment is safe to open please contact > Andy on x234. There are 0 attachments with this message. > ________________________________________________________________ > > > Dear R users, > > I want to retrieve "..." argument values within a function. Here is a > small > exmaple: > > myfunc <- function(x, ...) > { > if (hasArg(ylim)) a <- ylim > plot(x, ...) > } > > x <- rnorm(100) > myfunc(x, ylim=c(-0.5, 0.5)) > Error in myfunc(x, ylim = c(-0.5, 0.5)) : Object "ylim" not found > > > > I need to retrieve values of "ylim" (if it is defined when function is > called) for later use in the function. Can anybody give me some hint? > > Thanks a lot. > > Huan > > > > > This message and any attachments (the "message") is\ > intende...{{dropped}} > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > Simon Fear Senior Statistician Syne qua non Ltd Tel: +44 (0) 1379 644449 Fax: +44 (0) 1379 644445 email: [EMAIL PROTECTED] web: http://www.synequanon.com Number of attachments included with this message: 0 This message (and any associated files) is confidential and\...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
