On 11/05/2016 4:45 AM, Witold E Wolski wrote:
Hi,I am looking for a documentation describing how to manipulate the "..." . Searching R-intro.html gives to many not relevant hits for "..." What I want to do is something like this : image.2 <- function(x, col , ...){ # function is manipulating colors (adding a few) # since it changes colors it needs to update breaks if defined. breaks <- list(...)$breaks if( !is.null( list(...)$breaks ) ){ #manipulate breaks image(x, col, breaks = breaks ,...) }else{ image(x,col ,...) } } but in order to get it working I will need to remove breaks from ... since otherwise I am getting multiple defined argument for breaks.
If breaks is an argument that image.2 uses, you should just list it explicitly, and it won't become part of ... .
However, if you really want to do what you describe, you can do it using do.call. Replace
image(x, col, breaks = breaks, ...) with dots <- list(...) dots$breaks <- NULL do.call(image, c(list(x, col, breaks = breaks), dots))
So how to manipulate the "..." argument? Or should I use a different pattern
I'd recommend a different pattern, i.e. include breaks as an argument, and possibly use is.missing(breaks) to determine when it has not been used.
Duncan Murdoch ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
